PANCE Exam: Infectious Disease Review Questions & Answers

FUNGAL DISEASE

Question: What are some of the clinical conditions that can present with candidiasis?
Oral thrush, vaginitis, esophagitis, and mucocutaneous candida.

Question: What is the microscopic appearance of Candida albicans
Either as a singular oval budding yeast or as pseudohyphae (elongated).

Question: What types of patients are predisposed to develop disseminated candidiasis?
Intravenous drug users and those with indwelling catheters and hyperalimentation, which can lead to right-sided endocarditis.

Question: How is candidiasis of the esophagus diagnosed?
An air contrast barium swallow shows ulcerations with plaques. In contrast, herpes esophagitis produces punched out ulcerations with no plaques. Definitive diagnosis is made by upper GI endoscopy and fungal and viral cultures.

Question: Of the five antifungals listed, which drug would be the treatment of choice for each?

1. Oral candidiasis
2. Esophageal
3. Vaginal
4. Mucocutaneous
5. Disseminated

1. Fluconazole
2. Fluconazole
3. Nystatin
4. Ketoconazole
5. Amphotericin B or fluconazole

Question: What is the method of contracting Cryptococcus in a human?
Inhalation of contaminated soil, usually by bird droppings.

Which species of Cryptococcuscauses most human infections?
C. neoformans.

Question: What would a chest X-ray reveal in a patient with early infection caused by Cryptococcus?
A solitary nodule or a diffuse infiltrate.

Question: What is the drug(s) of choice for the treatment of Cryptococcus?
Amphotericin B with fluconazole or flucytosine.

Question: Where is histoplasmosismore commonly found in the United States?
Eastern and central United States, particularly in Mississippi, Ohio, and Missouri Valley areas.

Question: How does the histoplasmosis spore spread?
Any activity that will cause the spores to move from their original site such as dry, windy conditions, demolition of old buildings, and barns where birds and bats have helped the spores proliferate.

Question: What test is used to accurately diagnose histoplasmosis?
Cultures either from blood, marrow, tissue, or sputum via bronchoalveolar lavage.

Question: What is the drug of choice for the treatment of a histoplasmosis infection?
Amphotericin B.

Question: What is the newer and more appropriate species for a pneumocystis infection in humans?
Pneumocystis jiroveci. P. carinii infects only rats and not humans.

Question: What is the most common opportunistic infection in children and infants with HIV?
Pneumocystis carinii pneumonia (PCP)

Question: What is the definitive diagnostic test for pneumocystis infection?
Obtaining a respiratory tract specimen, either by tissue sample or aspiration of secretions.

Question: What is the drug of choice for the treatment of pneumocystis infection?
Trimethoprim-sulfamethoxazole IV.

Question: What if the patient is sulfa allergic or cannot tolerate the medication?
Alternate drug to use would be pentamidine.

Question: How is the diagnosis of pulmonary zygomycosis made?
By biopsy.

Question: How does one diagnose invasive aspergillosis?
By biopsy.

BACTERIAL DISEASE

Question: How is botulism contracted, and what are the principal clinical features?
It is contracted by consumption of contaminated foods, by injury from nonsterile objects (wound botulism), and in infants from intestinal colonization by Clostridium botulinum (lack of normal intestinal flora permit this colonization). The clinical features are that of a descending paralysis with complete ophthalmoplegia, bulbar, and somatic palsy.

Question: What is the best test to use to confirm a diagnosis of botulism?
Stool and/or gastric aspirate for culture.

Question: What is the treatment for adult foodborne illness caused by C. botulinum? For infant botulism?
For adults—Bivalent antitoxin A and B
For infants—Human-derived antitoxin

Question: If treating a botulism skinborne infection, what class of antibiotics should you avoid?
Aminoglycosides, because they may potentiate the neurological symptoms.

Question: Is the motor paralysis induced by botulinum toxin reversible?
It’s an irreversible paralysis, and recovery is from axonal sprouting from old sarcolemmal area to a new locus.

Question: What is the sine-quo-non of botulism poisoning presentation?
Bulbar palsy.

Question: What is the most common cause of sexually transmitted disease in the United States?
Chlamydia trachomatis infections.

Question: Can Chlamydia bacteria grow on independently?
No, they are obligate intracellular pathogens.

Question: What are the two most common forms of transmission of Chlamydia?
Close contact either sexually or via the birth canal.

Question: A 23-year-old male patient is complaining of dysuria with a discharge that is clear and thin in appearance. What is the most likely pathogen that presents with this finding?
Chlamydia urethritis infection.

Question: What is the drug of choice for the treatment of sexually transmitted Chlamydia?
Azithromycin.

Question: What is the treatment of neonatal conjunctivitis caused by C. trachomatis?
Erythromycin.

Describe lesions associated with chlamydia:
Painless, shallow ulcerations, papular or nodular lesions, and herpetiform vesicles that wax and wane.

Question: Describe the lesions associated with lymphogranuloma venereum (LV):
LV caused by Chlamydia presents as painless skin lesions with lymphadenopathy. Lesions may be papular, nodular, or herpetiform vesicles. Sinus formation, involving the vagina and rectum, are common in women.

Question: On a recent medical mission trip to East Africa, you are caring for several members of a village who have had painless diarrhea, which has the appearance of colorless “rice water” stools. There is no abdominal pain, but the villagers are dehydrated and have suspected electrolyte abnormalities. What would be the leading diagnosis?
Vibrio cholera outbreak.

Question: What is the most common mode of contamination of patients infected with V. cholera?
Contaminated water or food (uncooked or raw shellfish, dried fish, and vegetables held in ambient heat).

Question: What is the treatment for a patient with confirmed or suspected cholera?
Aggressive oral hydration along with electrolyte replenishment. If severe infection, oral doxycycline (one-time dose) or tetracycline can be used.

Question: What are the signs and symptoms of diphtheria?
Acute onset of exudative pharyngitis, high fever, and malaise. A pseudomembrane may form in the oropharynx with possible respiratory compromise. Powerful exotoxins directly affect the heart, kidneys, and nervous system. Diphtheria infection may lead to paralysis of the intrinsic and extrinsic eye muscles, which may be confused with bulbar palsy caused by Clostridium botulinum. Botulism does not cause fever.

Question: What confirmatory test is run for the diagnosis of diphtheria?
Culture, usually from the nose, throat, or mucous membrane lesion.

Question: What are the three considerations for the treatment of diphtheria?
1. Antitoxin—Before cultures are back and have high suspicion
2. Antibiotics—Erythromycin or Penicillin G
3. Immunization

Question: Do individuals with close contact to a diphtheria patient need to be watched?
Yes. You must observe them for up to a week for any signs of infection, culture the throat for diphtheria, and prophylaxis with erythromycin for a 10-day course, or IM Penicillin G.

Question: What percentage of patients with gonococcal genital infections have concomitant Chlamydia trichomatous infections?
45%. This is why treatment for gonorrhea includes ceftriaxone and doxycycline to cover both infections.

What is the most common type of gonorrheainfection that can be seen in newborns?
Conjunctivitis.

Question: N. gonorrhea is confirmed by what type of laboratory test?
Gram stain and culture. You will see gram-negative diplococci.

Question: A 10-year-old girl presents to your facility with a history and physical examination that is consistent with vaginitis producing thick, purulent yellow discharge. What is the likely pathogen for this, and is this the only thing that you need to be worried about for the patient?
The vaginitis with discharge as described is consistent with N. gonorrhea infection. A 10-year-old girl who present with this should give you a high suspicion for sexual abuse, as she should not get this type of infection.

Question: What is the recommended initial treatment for cases of gonorrhea?
Third-generation cephalosporins (specifically ceftriaxone) plus either doxycycline (100 mg bid for 7 days) or azithromycin (1 g PO × 1 dose) for presumptive coinfection with Chlamydia.

Question: What is the most common physical examination finding in an adult patient with disseminated gonorrhea?
Septic arthritis.

Question: Describe the skin lesions found in a patient with disseminated gonococcemia:
Umbilicated pustules with red halos.

Question: What is the course of treatment for disseminated gonorrhea?
7-day course of ceftriaxone or cefotaxime. If suspicion for meningitis, 10–14 days of treatment is recommended.

Question: What is the most common cause of bacterial enterocolitis in the United States?
Salmonella infection.

Question: How is Salmonella transmitted?
It is transmitted by humans and usually comes from contaminated water or food.

Question: Name the three types of infections that occur as a result of Salmonella:
Enterocolitis, typhoid, and septicemia.

Question: What are the features of typhoid fever?
Remember BIRDS FLEW:

Bradycardia
Insidious onset
Rose spots
Dicrotic pulse
Splenomegaly
Fever
Leukopenia
Epidemic
Widal reaction

Name the signs and symptoms for salmonella enterocolitis:
Fever, diarrhea, and abdominal pain.

Question: What test do you order to confirm a diagnosis of Salmonella?
Stool cultures most common. You can also obtain blood and urine cultures if examination is consistent.

Question: Which has a longer incubation period, staphylococci or salmonellae?
Salmonellae; it is generally ingested in small doses and then multiplies in the GI tract. Symptoms occur 6–48 hours after ingestion. Staphylococcus aureus has an incubation period of just 3 hours.

Question: What is the first-line treatment for salmonella enterocolitis?
Fluid and electrolyte replenishment.

Question: What is the pharmacological treatment for persistent salmonellosis?
Ampicillin, TMP-SMX, chloramphenicol.

Question: Antibiotics should be avoided with what infectious diarrhea?
Salmonella. Clear exceptions are severe cases of diarrhea in immunocompromised patients and in children younger than 6 months old.

Question: Which part of the GI tract does Shigella sp. infect more often?
The colon.

Question: In a patient who presents with diarrhea, high fever, headache, lethargy, confusion, a normal lumbar puncture, 45% band forms on the differential of his white blood count, and a blood culture that is positive for Escherichia coli, what is the most likely cause of the diarrhea?
Shigella. Blood cultures in shigella diarrhea are virtually never positive for shigella. When they are positive, they are more likely to be positive for Escherichia coli. Perhaps this is due to the fact that while Shigella is locally quite invasive at the mucosal level, it is very poorly invasive at the systemic level. Resident E. coli in the gut, however, take advantage of the disrupted mucosa and invade the blood stream.

Question: What is the microscopic makeup of Shigellasp.?
It is an aerobic, gram-negative bacillus.

Question: What is the primary transmission route of Shigella?
Fecal–oral.

Question: Does a stool sample culture give you a diagnosis for Shigella?
No. It will show fecal leukocytes, which is consistent with a colitis picture.

Do you treat Shigella with antibiotics?
In general, no, if the disease is self-limiting to less than 72 hours. Should the infection be prolonged, if there is significant diarrhea, dysentery, or an immunocompromised patient, and then antibiotics are used to shorten the duration of the illness and reduce the amount of fecal leukocytes in the stool.

Question: What is the treatment for Shigella sp.?
TMP-SMX or ciprofloxacin (if resistant).

Question: What causes tetanus?
Clostridium tetani. This organism is a gram-positive rod; it is vegetative and a spore former. It produces tetanospasmin, an endotoxin, which induces the disinhibition of the motor and autonomic nervous systems and thus the exhibition of tetanus clinical symptoms.

Question: What is the incubation period of tetanus?
Hours to months. The shorter the incubation period, the more severe the disease. The average age of incubation is 14 days.

Question: What is the most common presentation of tetanus?
“Generalized tetanus” with pain and stiffness in the trunk and jaw muscles. Trismus develops and results in risus sardonicus (“The Devil’s Smile”).

Question: Outline the treatment for tetanus:

Respiratory: Administer succinylcholine for immediate intubation if required.

Immunotherapy: Human tetanus immune globulin will neutralize circulating tetanospasmin and the toxin in the wound. However, it will not neutralize toxin fixed in the nervous system. Dose TIG 3000–5000 units. Prescribe tetanus toxoid, 0.6 mL IM, at 1 week and 6 weeks and 6 months.

Antibiotics: Clostridium tetani is sensitive to cephalosporins, tetracycline, erythromycin, and penicillin, but penicillin G is the drug of choice.

Muscle relaxants: Administer diazepam or dantrolene to help with the tetanic spasms.

Neuromuscular block: Prescribe pancuronium bromide, 2 mg plus sedation.

Autonomic dysfunction: Prescribe labetalol, 0.25–1.0 mg/min IV; or magnesium sulfate, 70 mg/kg IV load; then 1–4 g/hour continuous infusion is used to treat autonomic dysfunction. Administer MS, 5–30 mg IV infusion every 2–8 hours; and clonidine, .1.3 mg every 8 hour per NG.
Note: Fatal cardiovascular complications have occurred in patients treated with β-adrenergic blocking agents alone. Adrenergic blocking agents used to treat autonomic dysfunction may precipitate myocardial depression.

Question: Distinguish the key differences between strychnine and tetanus poisoning:
Tetanus poisoning produces constant muscle tension, whereas strychnine produces tetany and convulsions with episodes of relaxation between muscle contractions.

Question: What are the signs and symptoms of tularemia?
Indurated skin ulcers at the site of inoculation, regional lymphadenopathy, fever, shaking chills, cough, hemoptysis, SOB, rales or pleural rub, hepatosplenomegaly, and a maculopapular rash.

What is the treatment for tularemia?
Streptomycin. Mortality rate is 5% to 30% without antibiotic treatment.

Question: What is the most common symptom of tularemia?
Skin sores at the site of inoculation and lymphadenopathy (75%). Other symptoms include pneumonia, lesions in the GI system, infection of the eyes, fever, and headache.

Question: How is tularemia most commonly transmitted?
Via ticks and rabbits. Tularemia is caused by F. tularensis.

Question: What is the most common cause of cellulitis?
Streptococcus pyogenes. Staphylococcus aureus can also cause cellulitis though it is generally less severe and more often associated with an open wound.

Question: What is the most common cause of cutaneous abscesses?
Staphylococcus aureus.

Question: What percentage of dog and cat bites become infected?
About 10% of dog bites and 50% of cat bites become infected. Pasteurella multocida are the causative agents for 30% of dog bites and 50% of cat bites.

Question: A 6-year-old child presents with headache, fever, malaise, and tender regional lymphadenopathy about a week after a cat bite. A tender papule develops at the site. What is the diagnosis?
Cat-scratch disease. This condition usually develops 3 days to 6 weeks following a cat bite or scratch. The papule typically blisters and heals with eschar formation. A transient macular or vesicular rash may also develop.

Question: What is thought to be the mode of inoculation in cat-scratch disease?
Rubbing the eye after contact with a cat.

Question: What is the probable cause of an animal bite infection arising that develops in less than 24 hours? More thans 48 hours?
Less than 24 hours: Pasteurella multocida or streptococci. More than 48 hours: Staphylococcus aureus.

Question: What is the most common cause of gas gangrene?
Clostridium perfringens.

Question: What are the neurological features of brucellosis?
Mainly a chronic meningitis and the vascular complications thereof. However, cranial neuropathies, demyelination and mycotic aneurysms have all been described.

How is brucellosis spread?
By ingestion of contaminated milk and milk products. It may also be spread by contact with an infected animal (usually cattle). Brucella melitensis is the culprit.

Question: A 31-year-old man stepped on a nail at his job. The nail pierced through his sneaker and into his foot. His tetanus status is up to date. What is your main concern?
Infection with Pseudomonas that can lead to osteomyelitis. Pseudomonal infection is most commonly associated with hot, moist environments, such as sneakers and moisture in socks.

Question: What is the most common causative bacterium associated with right-sided endocarditis in IV drug abusers?
Staphylococcus aureus. Left-sided endocarditis in IV drug abusers is usually due to E. coli, Streptococcus, Klebsiella, Pseudomonas, or Candida.

Question: What are the major Jones criteria used to diagnose rheumatic fever?
Carditis, chorea (Sydenham), erythema marginatum, migratory polyarthritis, and subcutaneous nodules. The diagnosis requires either 2 major or 1 major and 2 minor with evidence of previous streptococcal infection.

Question: After finishing the prescribed dosage of penicillin for pharyngitis, your patient’s repeat culture still grows Streptococcus. What should you do?
Nothing. Most people are asymptomatic carriers and in most cases it is inconsequential.

Question: What is the cause of chancroid?
Hemophilus ducreyi. Patients with this condition present with one or more painful necrotic lesions. Suppurating inguinal lymphadenopathy may also be present.

Question: What is the most common infectious disease complication of both measles and influenza?
Pneumococcal pneumonia.

Question: Do household pets transmit Yersinia?
Yes.

Question: On Tuesday, you are driving home from work in rural California and pass three dead squirrels. On Wednesday, taking a different route, you pass two more dead squirrels. The following morning you see a 26-year-old male patient with enlarged tender lymphadenitis and a 105°F fever. What illness might you suspect?
Cases of human plague (Yersinia pestis) are sometimes heralded by squirrel die-offs. A squirrelly die-off occurs when the organism is introduced into a highly susceptible mammalian population, causing a high mortality rate among infected animals. This is referred to as epizootic plague.

Question: One day after a previously healthy adult has been admitted to the hospital after an accidental overdose of oral iron, she appears to become septic. What is the most likely organism causing her sepsis?
Yersinia enterocolitica. The growth of Y. enterocolitica appears to be enhanced after exposure to excess iron. This combined with intestinal damage to the mucosa by the iron may play a role in pathogenesis.

What is the treatment for Yersinia sp.?
TMP-SMX, tetracycline, and third-generation cephalosporin.

Question: What is Weil disease?
Weil syndrome is the less common variety of leptospirosis, with icterus, marked hepatic and renal involvement along with a bleeding diathesis being the main features, and hence the name leptospirosis-ictero-hemorrhagica.

Question: What is the most common neurological feature of leptospirosis?
Aseptic meningitis (present in over 50%).

Question: What clinical feature of leptospirosis sets it apart from other infections of the nervous system and hints at the diagnosis?
Hemorrhagic complications. These are not uncommon, and intraparenchymal and subarachnoid hemorrhages have been reported.

Question: Which organisms produce focal nervous system pathology via an exotoxin?
Clostridium diphtheria, Clostridium botulinum, Clostridium tetani, Staphylococcus aureus plus wood and dog ticks (Dermacentor A and B).

Question: How should you treat a patient who has been bitten by a wild raccoon?
Wound care, tetanus prophylaxis, RIG, 20 IU/kg (1/2 at bite site and 1/2 IM), and HDCV, 1 cc IM.

Question: Do animal bites from birds, reptiles, or rodents (hamster, squirrel, mouse, rat, gerbil, guinea pig, rabbit) require the rabies vaccine?
No, these types of animal bites do not carry rabies.

Question: Describe the skin lesions associated with a Pseudomonas aeruginosa infection.
Pale, erythematous lesions 1 cm in size with an ulcerated necrotic center.

Question: Why is needle aspiration preferred over incision and drainage for a fluctuant, acute cervical lymphadenitis?
Development of a fistula tract is possible if the patient has atypical mycobacterium or cat-scratch fever instead of bacterial lymphadenitis.

Question: What is the cause of granuloma inguinale?
The bacterium Donovania granulomatis, recently renamed Calymmatobacterium granulomatis.

Question: What triad is associated with Reiter syndrome?
Nongonococcal urethritis, polyarthritis, and conjunctivitis. Conjunctivitis is the least common and occurs in only 30% of the patients. Acute attacks respond well to NSAIDs.

What is the treatment for persistent E. coli?
Trimethoprim with sulfamethoxazole (TMP-SMX).

Question: What is the treatment for Giardia lamblia?
Quinacrine or metronidazole or furazolidone.

Question: What are the common features of Vibrio parahaemolyticus?
This condition is caused by organisms associated with oysters, clams, and crabs. Symptoms include cramps, vomiting, dysentery, and explosive diarrhea. Severe infections are treated with tetracycline and chloramphenicol.

Question: What are the antibiotics of choice in a wound resulting from a skin diving incident?
Ciprofloxacin or TMP-SMX.

Question: What is the most common gram-negative aerobe found in cutaneous abscesses?
Proteus mirabilis.

Question: Describe the Gram stain appearance of Staphylococcus aureus:
Gram-positive cocci in grapelike clusters.

Question: Which type of diarrhea-causing disease may be transmitted by pets?
Yersinia.

Question: Does H. influenzae typically cause abscesses?
No.

Question: What is the common pathogen in a cat bite?
Pasteurella multocida.

Question: What percentage of untreated group A β
-hemolytic streptococcal infections will progress to rheumatic fever?
3%. Increased incidence of the disease is noted in lower socioeconomic areas.

Question: What is used to control outbreaks of meningococcal meningitis?
Rifampin and ceftriaxone are used as chemoprophylaxis for contacts.


MYCOBACTERIAL DISEASE

Question: Why does therapy for tuberculosis (TB) take several months, when other infections usually clear in a matter of days?
Because the mycobacterium divide very slowly and have a long dormant phase, during which time they are not responsive to medications.

What is the typical timeframe for symptoms to appear for patients with TB?
1–6 months.

Question: What are some of the classic symptoms of TB?
Fevers, chills, cough, night sweats, weight loss, or poor weight gain.

Question: What are some radiographic findings on chest X-ray in a patient with TB?
Can be normal. Abnormalities can be increased markings of the hilar, mediastinal, and carinal nodes, atelectasis or infiltrate of a segment of a lobe; pleural effusions, cavitary lesions and miliary disease.

Question: What type of bacteria is TB?
It is an acid-fast bacillus.

Question: Name the two types of lesions found in TB:

1. Exudative lesions—Usually seen at the site of the lung that produces inflammatory reaction of the local tissue.
2. Granulomatous lesions—These are giant cells that have tubercle bacilli around the cells. Over time, these cells will heal but will leave fibrotic or calcified tissue behind.

Question: What percentages of TB infections are symptomatic?
Only 10%.

Question: What is the main treatment drug for TB?
Rifampin.

Question: What is the most common side effect of rifampin?
Orange discoloration of urine and tears.

Question: What is the triple drug treatment for pulmonary TB, and for how long on each drug?
Isoniazaid, 6 months
Rifampin, 6 months
Pyrazinamide, 2 months
For HIV
+ patients, ethambutol is added with this regimen for 9–12 months duration.

Question: If the result of a patient’s PPD is read as 3 mm of induration and then 15 mm of induration following the placement of the second PPD 2 weeks later, which study should be considered the more reliable?
The second study with an induration of 15 mm. With time, the body’s memory of the tuberculosis infection may wane. The placement of a PPD may stimulate that memory. This is what is referred to as the “booster phenomenon.” The boosted result is considered to be the reliable result.

List the four groups of atypical mycobacterium, the common bacteria in each group, where it is found, the physical effects, and what drug it used to treat:


Question: What regions of the United States have more cases of coccidiomycosis?
Typically the Southwest states (Arizona, New Mexico, Southern California) and some in the Ohio valley. It is sometimes referred to as Valley fever or the San Joaquin fever

Question: How is the diagnosis of coccidiomycosis made?
By culture or staining of sputum, bronchoalveolar lavage or tissue, and by a positive serology.

Question: What is the treatment for a pulmonary infection due to coccidiomycosis?
Amphotericin B is used for serious infections. Minor infections do not require medications.

What is the cause of granuloma inguinale?
Calymmatobacterium granulomatis. Onset occurs with small papular, nodular, or vesicular lesions that develop slowly into ulcerative or granulomatous lesions. Lesions are painless and are located on mucous membranes of the genital, inguinal, and anal areas.

Question: A patient from the Philippines has a hypopigmented patch that is lacking in sensation. What is the most likely cause of his problem?
Leprosy (Mycobacterium leprae).

Question: What is the mode of transmission for leprosy?
It is human-to-human contact mostly but in prolonged contact with the patient.

Question: What are the two forms of leprosy?
Tuberculin and lepromatous.

Question: What is the treatment for leprosy?
Dapsone alone causes resistance. However, a combination of dapsone and rifampin is recommended.


PARASITIC DISEASE

Question: List three common protozoa that can cause diarrhea:

1. Entamoeba histolytica
—Found worldwide. Although half of the infected patients are asymptomatic, the usual symptoms consist of N/V/D/F, anorexia, abdominal pain, and leukocytosis. Determine the presence of this organism by ordering stool tests and performing an ELISA for extraintestinal infections. Treatment is with metronidazole or tinidazole followed by chloroquine phosphate.

2. Giardia lamblia
—Found worldwide. This organism is one of the most common intestinal parasites in the United States. Symptoms include explosive watery diarrhea, flatus, abdominal distention, fatigue, and fever. The diagnosis is confirmed via a stool examination. Treatment is with metronidazole.

3. Cryptosporidium parvum
—Found worldwide. Symptoms are profuse watery diarrhea, cramps, N/V/F, and weight loss. Treatment is supportive care. Medications may be needed for immunocompromised patients.

Question: What is the most common intestinal parasite in the United States?
Giardia. Cysts are obtained from contaminated water or by hand-to-mouth transmission. Symptoms include explosive foul smelling diarrhea, abdominal distention, fever, fatigue, and weight loss. Cysts reside in the duodenum and upper jejunum.

Question: What are the characteristic features of cerebral amebiasis, and what is the pathogenic organism?
Cerebral amebiasis is usually a secondary infection, and patients often have intestinal or hepatic amebiasis. The causative organism is Entamoeba histolytica. The clinical features are that of intracerebral abscesses causing focal neurological signs. Frontal lobes and basal nuclei are common sites of abscess formation.

What is the treatment for amebiasis with neurological involvement?
E. histolytica is treated with metronidazole, emetine, and chloroquine. Naegleria species is treated with amphotericin and rifampicin.

Question: Besides the intestinal and cerebral manifestations related to Entamoeba histolytica, what is another potential complication related to the parasite?
It can also develop liver abscess. The signs and symptoms of these patients will have right upper quadrant pain, fevers, and weight loss with a tender, enlarged liver.

Question: Which parasite is found in 25%–50% of women, causes a watery, foul-smelling vaginal discharge, and microscopically appears as a pear-shaped organism with four flagellates anteriorly?
Trichomonas vaginalis.

Question: What is the antibiotic of choice for this type of infection?
Metronidazole.

Question: Where is the hookworm Necator americanus infection acquired?
In areas where human fertilizer is used and people don’t wear shoes. Patients present with chronic anemia, cough, low-grade fever, diarrhea, abdominal pain, weakness, weight loss, eosinophilia, and guaiac positive stools. A diagnosis is confirmed if ova are present in the stool. Treatment includes mebendazole or pyrantel pamoate.

Question: What are the signs and symptoms of Trichuris trichiura?
This hookworm lives in the cecum. Complaints include anorexia, abdominal pain especially RUQ, insomnia, fever, diarrhea, flatulence, weight loss, pruritus, eosinophilia, and microcytic hypochromic anemia. Examining for ova in the stool makes a diagnosis. Mebendazole is the treatment of choice.

Question: A patient attended a walrus, bear, and pork roast. He now has N/V/D/F, urticaria, myalgia, splinter hemorrhages, muscle spasm, headache, and a stiff neck. What physical finding will clinch the diagnosis?
Periorbital edema is pathognomonic for infection with Trichinella spiralis. Patients may have acute myocarditis, nonsuppurative meningitis, and catarrhal enteritis bronchopneumonia. Laboratory studies may reveal leukocytosis, eosinophilia, ECG changes, and elevated CPK. Diagnosis is confirmed with a latex agglutination, skin test, complement fixation, or bentonite flocculation test. A stool examination is not helpful after the initial GI phase for confirming the diagnosis.

Question: How are tapeworms transmitted into humans?
They are usually acquired by ingesting undercooked fish, which has the larvae present. The larvae then proliferate. In the cases of cystircecosis and hydatid disease, the eggs are ingested.

Question: Which is the most common tapeworm in the United States?
Hymenolepis nana (dwarf tapeworm). Infections are spread via fecal/oral spread and occur in institutionalized patients, typically children.

Which intestinal parasites are known to cause anemia as their major manifestation?
Hookworms. Three species of hookworms affect humans. These include Ancylostoma duodenale, Necator americanus, and Ancylostoma ceylanicum.

Question: Hookworm is associated with what sort of anemia?
Iron deficiency anemia.

Question: Fish tapeworm (Diphyllobothrium latum) is associated with what type of anemia?
Pernicious anemia.

Question: Roundworm is associated with what GI problem?
Small bowel obstruction.

Question: In general, what kinds of education can you provide to patients to prevent infections that arise from hookworms?
Beef and pork products must be cooked thoroughly as well as hands washed properly. Prevention from farmers to prevent ingestion of human waste by cows and pigs is also paramount.

Question: Name the four types of malaria; and which one is the most prevalent?
1. Plasmodium falciparum (most prevalent)
2. P. vivax
3. P. ovale
4. P. malariae

Question: What is the most deadly form of malaria?
Plasmodium falciparum.

Question: What is the vector for malaria?
The female anopheline mosquito.

Question: What laboratory findings are expected for a patient with malaria?
Normochromic normocytic anemia, a normal or depressed leukocyte count, thrombocytopenia, an elevated sedimentation rate, abnormal kidney and LFTs, hyponatremia, hypoglycemia, and a false-positive VDRL.

Question: How is malaria diagnosed?
Visualization of parasites on Giemsa-stained blood smears. In early infection, especially with P. falciparum, parasitized erythrocytes may be sequestered and undetectable.

Question: How is P. falciparum diagnosed on blood smear?
1. Small ring forms with double chromatin knobs within the erythrocyte
2. Multiple rings infected within red blood cells
3. Rare trophozoites and schizonts on smear
4. Pathognomonic crescent-shaped gametocytes
5. Parasitemia exceeding 4%

What is the drug of choice for treating P. vivax, ovale, and malariae?
Chloroquine.

Question: How is uncomplicated chloroquine-resistant P. falciparum treated?
Quinine plus pyrimethamine-sulfadoxine plus doxycycline or mefloquine.

Question: What are the adverse effects of chloroquine?
N/V/D/F, pruritus, headache, dizziness, rash, and hypotension.

Question: Which hemoglobin provides the greatest innate resistance to falciparum malaria?
Erythrocytes of patients who are heterozygous for sickle cell hemoglobin (sickle cell trait) are resistant to malaria.

Question: What species of Plasmodium is resistant to chloroquine?
Falciparum.

Question: A 5-year-old boy presents with his mother complaining of anal itching that has been present for the last 3 days. On examination, the child has small whitish worms that were obtained by the “Scotch tape” method. What diagnosis does this child have?
Pinworms.

Question: What is the most common helminth in the United States?
Enterobius.

Question: What is the most common physical complaint in individuals with an Enterobius infection?
Perianal pruritus.

Question: What is the treatment for pinworms?
Mebendazole as well as proper teaching about hand hygiene to the patient.

Question: Name the most common form of transmission for toxoplasmosis:
Ingestion of the cysts via uncooked meat or feline feces.

Question: Is there a risk for transmission of toxoplasmosis from a pregnant woman to the fetus?
Yes, but only if the mother gets infected during the pregnancy.

Question: Which types of pregnant women are at increased risk for developing toxoplasmosis?
Women who are cat owners. They must be educated to refrain from cleaning out the cat litter as well as told to avoid eating uncooked meats.

Question: What pathological findings are seen in the brain biopsy of toxoplasma encephalitis?
Presence of tachyzoites around the necrotic lesion.

What are some important radiological differences between intracranial toxoplasmosis and lymphoma?

1. Intracranial toxoplasmosis is usually multiple, whereas lymphomas are usually solitary, at least in the beginning.

2. Enhancement—Both may enhance with gadolinium on the MRI scan; however, toxoplasma lesions are usually round and discrete in comparison to the lymphoma.

3. Thallium 201 SPECT scan—Lymphomas usually show increased activity in the thallium scans compared to toxoplasmosis, which has poor uptake.

4. Location—Toxoplasmosis is usually in the deeper structures such as basal ganglia, or the gray white junction, whereas the lymphomas usually present themselves in the periventricular areas. However, biopsy is still necessary to make the diagnosis since imaging studies may overlap.

Question: What is the current recommended treatment for intracranial toxoplasmosis in HIV disease?
This is usually a combination therapy with sulfadiazine, pyrimethamine, and folinic acid.

Question: How is Chagas disease transmitted?
By the blood-sucking Reduviid “kissing” bug, blood transfusion, or breast feeding. A nodule or chagoma develops at the site. Symptoms include fever, headache, conjunctivitis, anorexia, and myocarditis. CHF and ventricular aneurysms can occur. The myenteric plexus is involved and may result in megacolon. Laboratory findings include anemia, leukocytosis, elevated sedimentation rate, and ECG changes, such as PR interval, heart block, T wave changes, and arrhythmias.

Question: What causes swimmer itch (Schistosome dermatitis)?
An invading cercariae.

Question: What is the vector of trypanosomiasis?
Tsetse fly.

Question: What is the infectious agent of elephantiasis?
Nematode microfilaria.

Question: What vector transmits Chagas disease (Trypanosoma cruzi)?
Reduviid (assassin or kissing bug).

Question: Cysticercosis is associated with:
New onset seizure.

Question: Onchocerciasis (from Onchocerca volvulus) is associated with what visual deficit?
Blindness. This is referred to as river blindness.

Question: Chagas disease is associated with:
Acute myocarditis. Trypanosoma cruzi invades the myocardium resulting in myocarditis. Conduction defects may occur. The vector for this parasite is the insect reduviid.

What is the most frequently transmitted tick-borne disease?
Lyme disease. The causative agent is a spirochete (Borrelia burgdorferi), the vectors are Ixodes dammini, I. pacificus, Amblyomma americanum, and Dermacentor variabilis.

Question: What areas of the United States report the highest incidence of Lyme disease?
New England, the middle Atlantic, and upper Midwestern states.

Question: What are the signs and symptoms of Lyme disease?

Stage I: In the first month after the tick bite, patients can present with fever, fatigue, malaise, myalgia, headache, and a circular macule or papule lesion with a central clearing at the site of the tick bite that gradually enlarges (erythema chronicum migrans).

Stage II: (Weeks to months later) This stage involves neurological abnormalities such as meningoencephalitis, cranial neuropathies, peripheral neuropathies, myocarditis, and conjunctivitis to blindness.

Stage III: (Months to years) Migratory oligoarthritis of the large joints, neurological symptoms such as subtle encephalopathy (mood, memory, and sleep disturbances) polyneuropathy, cognitive dysfunction, and incapacitating fatigue.

Question: How is Lyme disease diagnosed?
Immunofluorescent and immunoabsorbent assays identify the antibodies to the spirochete. Treatment includes doxycycline or tetracycline, amoxicillin, IV penicillin (V in pregnant patients), or erythromycin.

Question: What is the vector and causative organism of Lyme disease?
The vector is Ixodes dammini, and the organism is Borrelia burgdorferi. It is the most frequently transmitted tick-borne disease.

Question: Which two diseases are transmitted by the deer tick, Ixodes dammini?
Lyme disease and babesiosis.

Question: At which stage of Lyme disease does neurological involvement occur?
The second and third stages. Second-stage cranial neuropathies, meningitis and radiculoneuritis. Third-stage encephalitis, and a variety of CNS manifestations including stroke like syndromes, extrapyramidal, and cerebellar involvement.

Question: Describe the skin lesion seen in Lyme disease:
A large distinct circular skin lesion called erythema chronicum migrans. It is an annular erythematous lesion with central clearing.

Question: When does ECM show up in Lyme disease?
Stage I, which is 3–32 days after the bite.

Question: How do patients present with babesia infection?
Intermittent fever, splenomegaly, jaundice, and hemolysis. The disease may be fatal in patients without spleens. Treatment is with clindamycin and quinine.

Which type of paralysis does tick paralysis cause?
Ascending paralysis. The venom that causes the paralysis is probably a neurotoxin. A conduction block is induced at the peripheral motor nerve branches and thereby prevents the release of acetylcholine at the neuromuscular junction; 43 species of ticks have been implicated as causative agents.

Question: What tick-borne disease is also harbored in wild rabbits?
Tularemia.

Question: A patient presents with sudden onset of fever, lethargy, a retro-orbital headache, myalgias, anorexia, nausea, and vomiting. She is extremely photophobic. The patient has been on a camping trip in Wyoming. What tick-borne disease might cause these symptoms?
Colorado tick fever. This is caused by a virus of the genus Orbivirus and the family Reoviridae. The vector is the tick D. andersoni. The disease is self-limited; treatment is supportive.

Question: Dermacentor andersoni (wood tick) is a pesky arthropod associated with four tick-borne illnesses! Name these illnesses and the cause of each:

1. Rocky Mountain spotted fever (RMSF)—caused by Rickettsia rickettsii; Dermacentor andersoni is a vector.
2. Tick paralysis—caused by a neurotoxin. The symptoms, consisting of ascending paralysis with decrease or loss of DTRs, are similar to those associated with Guillain-Barré syndrome.
3. Q fever—caused by Coxiella burnetii (a Rickettsiae).
4. Colorado tick fever—caused by an arbovirus.

Question: Which condition resembles Guillain-Barre syndrome, the appropriate treatment of which results in miraculous complete improvements often within a day?
Tick paralysis, which results in an ascending paralysis within a few days of attack by the tick Dermacentor (hard tick). This releases a toxin in its saliva, which is responsible for the neuromuscular blockade. Removal of the tick results in resolution of the weakness that begins within hours.

Question: What is the common name for Dermacentor andersoni?
Wood tick.

Question: What causes Q fever?
Coxiella burnetii, also known as Rickettsia burnetii. It is found in the Dermacentor andersoni tick.

Question: Describe a patient with tick paralysis:
Bulbar paralysis, ascending flaccid paralysis, paresthesias of hands and feet, symmetric loss of deep tendon reflexes, and respiratory paralysis.

Question: What kind of tick transmits Rocky Mountain spotted fever (RMSF)?
The female andersoni tick which transmits Rickettsia rickettsii.

Question: Where do the majority of Rocky Mountain spotted fever cases come from?
North Carolina, South Carolina, Tennessee, Oklahoma, and Arkansas comprise 56% of all cases.

What is the most common symptom in RMSF?
Headache. This occurs in 90% of patients.

Question: A patient presents a 40°C fever and a erythematous, macular, and blanching rash which becomes deep red, dusky, papular, and petechial. The patient is vomiting and has a headache, myalgias, and cough. Where did the rash begin?
Rocky Mountain spotted fever (RMSF) rash typically begins on the flexor surfaces of the ankles and wrists and spreads centripetally and centrifugally.

Question: Which test confirms RMSF?
Immunofluorescent antibody staining of a skin biopsy or serologic fluorescent antibody titer. The Weil-Felix reaction and complement fixation tests are no longer recommended.

Question: Which antibiotics are prescribed for the treatment of RMSF?
Tetracycline or chloramphenicol. Antibiotic therapy should not be withheld pending serologic confirmation.

Question: What antibiotic is used to treat Rocky Mountain spotted fever in a patient allergic to tetracycline?
Chloramphenicol.

Question: A 24-year-old male patient presents with a painless ulcer to the glans penis. What is the likely diagnosis?
Primary chancre from syphilis. These generally erupt within 2–10 weeks from exposure.

Question: What is the most common lesion that is seen in secondary syphilis?
Condyloma lata. These are mainly found on the genital region.

Question: What are some signs and symptoms of secondary syphilis?
Patchy alopecia, fevers, chills, myalgias, weight loss, headache, and malaise.

Question: A patient is infected with Treponema pallidum. What is the treatment?
The type of treatment depends upon the stage of the infection. Primary and secondary syphilis are treated with benzathine penicillin G (2.4 million units IM × 1 dose) or doxycycline (100 mg bid PO for 14 day). Tertiary syphilis is treated with benzathine penicillin G, 2.4 million units IM × 3 doses 3 weeks apart.

Question: Is the vasculitis that is seen in syphilis, a large or a small vessel disease?
Both. Large vessel (Heubner arteritis) is caused by adventitial lymphocytic proliferation of large vessels, and is commonly seen in the late meningovascular syphilis. The small vessel (Nissl-Alzheimer) vasculitis is the dominant vasculitic pattern in the paretic neurosyphilis.

Question: What is the recommended treatment for neurosyphilis?
Intravenous penicillin G. Follow-up CSF examinations are mandatory.

What complication may arise from aggressive treatment of neurosyphilis with penicillin?
Jarisch-Herxheimer reaction. It is due to a release of endotoxin when large numbers of spirochete are lysed during the penicillin treatment, and consists of mild fever, malaise, headache, arthralgia, and may produce a temporary worsening of the neurological status.

Question: What are five infectious diseases that give false-positive treponemal tests (FTA, MHA-TP, TPI) for syphilis?
Yaws, pinta, leptospirosis, rat-bite fever (Spirillum minus), and Lyme disease.

Question: What are five diseases that give false-positive non-treponema (VDRL, RPR) tests for syphilis?
Infectious mononucleosis, connective tissue diseases, tuberculosis, endocarditis, and intravenous drug abuse.

Question: A woman comes to your office frantic because her husband has just received a positive VDRL result. They have been happily married for 35 years and she can’t believe he has been unfaithful. Is it at all possible that he has been loyal to his wife?
Yes. False-positive tests can occur if the patient has had a viral or mycoplasma infection in the near past, if the patient is an IV drug user, or if the patient has SLE. The presence or absence of syphilis can be confirmed with the fluorescent treponemal antibody absorption test (FTA-ABS).


VIRAL DISEASE

Question: What is the most common cause of congential anomalies in the United States?
Cytomegalovirus (CMV).

Question: Name the forms of transmission of CMV in the different stages of life—fetus/infant, adolescent, and adult:
Fetus/infant—across placenta, during birth from canal, or through breast milk
Adolescent—saliva
Adult—sexual contact; both semen and cervical discharge, blood transfusions, and organ transplants

Question: Name the forms of anomalies in infants with CMV and what percentage of infants with CMV present with these problems?
Seizures, deafness, jaundice, microcephaly, and purpura. About 20% of the infants with CMV will have one of these conditions.

Question: How is the diagnosis of CMV made?
By the use of immunofluorescent antibody tests known as “shell vials.” An alternative test is the PCR assay.

Question: Name two CMV-related illnesses that can affect AIDS patients:
CMV colitis and retinitis. In other immunocompromised patients it can cause pneumonitis and hepatitis.

Question: What is the treatment for CMV infections?
Ganciclovir is the first-line treatment. Valganciclovir can be used as an alternate drug and also in retinitis cases.

Question: What causes infectious mononucleosis?
Epstein-Barr virus (EBV).

Are there any other illnesses that EBV can cause?
Yes, Burkitt lymphoma, nasopharyngeal cancer, B-cell lymphomas, and hairy leukoplakia seen more commonly in AIDS patients.

Question: How is EBV transmitted?
Through the saliva.

Question: What percentage of Americans have the antibody to fight against EBV?
90%.

Question: What patients are at risk to get the virus?
Immunocompromised, first few years in life as a child, and lower socioeconomic classes.

Question: Name the hallmark characteristics seen in patients with EBV (infectious mononucleosis):
Fever, sore throat, malaise, cervical lymphadenopathy, and anorexia.

Question: A 17-year-old adolescent boy who has recently been diagnosed with infectious mononucleosis. He is in high school and plays for the football team. What are some considerations that need to be addressed for all patients with mono, and what do you need to tell your patient?
All patients who have infectious mono need to have a careful examination of the spleen, which can enlarge, and in some cases of mono rupture. In rare cases, hepatomegaly can occur. The patient has to be held from playing any contact sport until the virus has subsided and he has been reevaluated to resume contact sports.

Question: What is the average length of illness in infectious mononucleosis?
56–60 days.

Question: How is the diagnosis of EBV made?
Two methods: one by hematologic and measuring the numbers of abnormal lymphocytes on smear and second by immunologic. There is an heterophil antibody test and a EBV-specific antibody test.

Question: What is the treatment for EBV?
Mainly supportive care, hydration, pain medications for sore throat, acetaminophen for fever, and prevention of injury of splenic injury.

Question: What causes erythema infectiosum?
It is parvovirus B19 and is referred to as “fifth disease” or “slapped cheek syndrome.”

Question: Is there a test that can determine erythema infectiosum?
Yes, the detection of IgM antibodies could be run; however, it is mainly a diagnosis on examination.

Question: Is there a specific treatment for fifth disease?
No, it is only supportive care of any symptoms.

What is the most common site of a herpes simplex I infection?
The lower lip. These lesions are painful and can frequently recur since the virus remains in the sensory ganglia. Recurrences are generally triggered by stress, sun, and illness.

Question: What is the main transmission of HSV-1 and HSV-2?
HSV-1: Saliva
HSV-2: Sexual contact

Question: Where does HSV lie dormant within the body?
It is held latent in the sensory ganglion cells.

Question: What STD pathogens cause painful ulcers?
Type II genital herpes and chancroid.


Question: Name the different forms of HSV-1 and HSV-2:


A 27-year-old woman who is 36 weeks pregnant and has a past history of HSV-2 but has been symptom free for the last several months. What considerations do you have to make in this patient’s case?
She may need a caesarean section if by term she has either active lesions present of positive viral cultures.

Question: What is the treatment for patients with HSV?
Acyclovir.

Question: Is there any advantage for long-term suppressive therapy for a patient with HSV?
Yes, long-term therapy can be helpful in reducing the number and severity of outbreaks. Valacyclovir and famciclovir are drugs of choice.

Question: Describe the pathophysiologic features of HIV:
HIV attacks the T4 helper cells. The genetic material of HIV consists of single-stranded RNA. HIV has been found in semen, vaginal secretions, blood and blood products, saliva, urine, cerebrospinal fluid, tears, alveolar fluid, synovial fluid, breast milk, transplanted tissue, and amniotic fluid. There has been no documentation of infection from casual contact.

Question: How quickly do patients infected with HIV become symptomatic?
5%–10% develop symptoms within 3 years of seroconversion. Predictive characteristics include a low CD4 count and a hematocrit less than 40. The mean incubation time is about 8.23 years for adults and 1.97 years for children younger than 5 years.

Question: A 22-year-old man, who has no significant medical history and is taking no medication, has a creamy white coat on his tongue. The substance easily rubs off, revealing an erythematous base. What should you be most concerned about?
HIV. In a patient who has no obvious reason for having an overgrowth of oral candida, HIV should be suspected. Other causes for oral thrush overgrowth include cancer, systemic illness, neutropenia, diabetes, adrenal insufficiency, nutritional deficiencies, or an immunocompromised state.

Question: An HIV-positive patient presents with a history of weight loss, diarrhea, fever, anorexia, and malaise. She is also dyspneic. Laboratory studies reveal abnormal LFTs and anemia. What is the most likely diagnosis?
Mycobacterium avium intracellulare. Laboratory confirmation is made by an acid-fast stain of body fluids or by a blood culture.

Question: What are the signs and symptoms of CNS cryptococcal infection in an AIDS patient?
Headache, depression, lightheadedness, seizures, and cranial nerve palsies. A diagnosis is confirmed by an India ink prep, a fungal culture, or by a testing for the presence of cryptococcal antigens in the CSF.

Question: What is the most common eye finding in AIDS patients?
Cotton wool spots. It has been proposed that the cotton wool spots are associated with PCP. These finding may be hard to differentiate from the fluffy, white, often perivascular retinal lesions that are associated with CMV.

What is the most common cause of retinitis in AIDS patients?
Cytomegalovirus. Findings include photophobia, redness, scotoma, pain, or a change in visual acuity. On examination, fluffy white retinal lesions may be evident.

Question: What is the most common opportunistic infection in AIDS patients?
Pneumocystis carinii (PCP). Symptoms may include a nonproductive cough and dyspnea. A chest X-ray may reveal diffuse interstitial infiltrates, or it may be negative. Although Gallium scanning is more sensitive, false positives occur. Initial treatment includes TMP-SMX. Pentamidine is an alternative.

Question: What is HAART?
HAART is an acronym for
Highly
Active
Anti
retroviral
Therapy. This is a combination of antiretroviral medications that can nearly completely suppress HIV viral replication. Medications used are nucleoside reverse transcriptase inhibitors and protease inhibitors.

Question: What is PEP and when can it be used?
PEP is an acronym for
Post
Exposure
Prophylaxis. It is a combination of HIV medications used to try to prevent HIV infection in individuals who have been exposed to the HIV virus. It should be used as soon as possible but definitely within 72 hours.

Question: What is the most common gastrointestinal complaint in AIDS patients?
Diarrhea. Many of the medications used to treat HIV have GI side effects. Hepatomegaly and hepatitis are also typical. Conversely, jaundice is an uncommon finding. Cryptosporidium and Isospora are the common causes of prolonged watery diarrhea.

Question: What is the current recommended treatment for intracranial toxoplasmosis in HIV disease?
This is usually a combination therapy with sulfadiazine, pyrimethamine, and folinic acid.

Question: What is the nature of CNS lymphoma in AIDS?
They are almost all tumors of B cell origin. They may be large cell immunoblastic, or small noncleaved cell lymphoma.

Question: Which virus is considered responsible for AIDS associated CNS lymphoma?
Epstein-Barr virus (EBV).

Question: What is the meaning of the term reverse transcriptase in the description of HIV?
Under normal circumstances, the transcription of a protein in a human cell occurs in a forward direction going from DNA to RNA. In reverse transcriptase, the transcription proceeds from RNA to DNA. HIV is a reverse transcriptase or a “retrovirus” that needs to be incorporated into the human genome by the reverse transcription before replicating.

Question: What life-threatening infection is most commonly associated with AIDS patients?
Pneumocystis carinii pneumonia (PCP).

What often causes a change in visual acuity in AIDS patients?
Cytomegalovirus.

Question: Which type of malignancy is most commonly associated with AIDS?
Kaposi sarcoma, followed by non-Hodgkin lymphoma.

Question: How many years does a patient usually live after being diagnosed with HIV?
It depends. Life expectancy in a 20-year-old on therapy is about 29 additional years. However, patients who start therapy and are diagnosed with a CD4 count lower than 100 cells/mm3 have an average of 12 extra years, those with a count of 200 cells/mm3 or higher have an average of 30 extra years, and those with a history of injectable drug use have comparatively lower extra years (12 years).

Question: Describe the AIDS dementia complex, which is also known as HIV-I encephalopathy:
A progressive disease caused directly by HIV-I. It is present in one-third of AIDS patients and is characterized by recent memory impairment, concentration deficit, elevated DTRs, seizures, and frontal release signs.

Question: What is the most common cause of focal encephalitis in AIDS patients?
Toxoplasma gondii.

Question: What is the risk of transmission of HIV from an HIV-infected person following a needle stick exposure?

0.3%–0.5% on average. (Although this varies depending on needle gauge and depth and site of insertion.)

Question: What are the most common adverse effects of AZT in an AIDS patient?
Granulocytopenia and anemia.

Question: What signs indicate an HIV-positive patient is at increased risk for opportunistic infections like PCP?
An absolute CD4 count of less than 200 and a CD4 lymphocytic percentage of less than 20.

Question: What immunizations are recommended for patients with HIV?
IPV and Td every 10 years
Influenza vaccine yearly
Pneumococcal vaccine once
Hepatitis B vaccine for at risk patients
Hib and MMR are optional

Question: At what point should AZT treatment begin in an asymptomatic patient with HIV?
When the CD4+ count reaches 300 cells/mm3

Question: What is the prophylactic regime of choice for PCP in patients with AIDS?
Trimethoprim-sulfamethoxazole DS should be started when the CD4+ count reaches 200 cells/mm3.

At what point should prophylaxis treatment against Mycobacterium avium intracellulare and toxoplasmosis be started in patients with AIDS?
When the CD4+ count reaches 100 cells/mm3.

Question: Immunocompromised patients can safely be given which vaccines?
Killed or inactivated vaccines:
Diphtheria
H. influenzae
Influenza
Pneumococcal
Enhanced inactivated polio
Hepatitis
Pertussis
Tetanus
It may be easier to remember the vaccines that should be avoided. The following are live, attenuated vaccines: Oral polio and MMR.

Question: Human papillomavirus (HPV) originates as tumors from what type of cell?
Squamous cells.

Question: How is HPV transmitted?
Skin-to-skin contact, usually sexual contact.

Question: What is the cause of condylomata acuminata?
Papilloma virus.

Question: Which types of HPV cause carcinoma of the cervix and penis?
Types 16 and 18.

Question: What medium is used to detect occult premalignant lesions caused by HPV?
Acetic acid prep.

Question: What is the main treatment for HPV?
Podophyllin. Genital warts can be either burned off or cryotherapy be used.

Question: What is the vaccine for the prevention of HPV, and what types of HPV does it protect against?
The vaccine Gardisil is available and protects against HPV 6 and 11 (genital warts) and 16 and 18 (cervical cancer).
The vaccine is administered to females between the ages of 9 and 26 years.

Question: What strain of influenza is more common in adults? In children?
Adults: Influenza A
Children: Influenza B

What strain of influenza is most virulent?
Influenza A.

Question: Influenza epidemics and pandemics are generally associated with which strain of influenza?
Influenza A.

Question: Amantadine is 70%–90% effective in preventing which strain of influenza?
Influenza A. Amantadine should be prescribed as chemoprophylaxis in immunocompromised patients who are not vaccinated or as a supplement to vaccination. It can also be given to healthy unvaccinated people who want to avoid the flu. Over the last few years, the use of amantidine for treatment of influenza has fallen out of favor due to higher resistance (over 90%) to the drug.

Question: When should the influenza vaccine be given?
In September or October, about 1 to 2 months before the influenza season begins. The vaccine, unlike amantadine, is protective against influenza A and B.

Question: What is a contraindication to the administration of the influenza vaccine?
A history of anaphylactic hypersensitivity to eggs or their products.

Question: How is the influenza virus transmitted?
By respiratory droplets.

Question: Name the signs and symptoms of a patient with influenza:
Fevers, chills, malaise, nonproductive cough, myalgias, headache, and sore throat.

Question: What is a potential respiratory complication to influenza?
Bacterial pneumonia.

Question: What is the most common pathogen for this type of pneumonia?
Staphylococcus aureus.

Question: Name two drugs approved for the treatment of influenza:
Oseltamivir (Tamiflu) and zanamivir (Relenza).

Question: What is the most common clinical finding on examination in a patient with mumps?
Parotid gland swelling.

Question: What are some prodromal symptoms in patients with mumps?
Fevers, malaise, and anorexia.

Question: What is a key examination that must be done in a male patient with mumps?
You must examine the scrotum to look for acute orchitis.

Besides orchitis in men, what is another potentially serious complication related to mumps?
Meningitis.

Question: How is mumps transmitted?
Respiratory droplets. It has a high peak incidence in the winter months.

Question: What is the treatment for mumps?
There is no treatment. If orchitis occurs, immediate consultation with a urologist in indicated. If suspicion for meningitis, appropriate treatment for the infection is warranted.

Question: How can mumps be prevented?
By giving the live attenuated mumps vaccine as scheduled. This is usually the MMR vaccine.

Question: Explain the pathophysiology of rabies:
Infection occurs within the myocytes for the first 48–96 hours. It then spreads across the motor endplate and ascends and replicates along the peripheral nervous system, axoplasm, and into the dorsal root ganglia, spinal cord, and CNS. From the gray matter, the virus spreads by peripheral nerves to tissues and organ systems.

Question: What is the characteristic histologic finding associated with rabies?
Eosinophilic intracellular lesions within the cerebral neurons called Negri bodies are the sites of CNS viral replication. Although these lesions occur in 75% of rabies cases and are pathognomonic for rabies, their absence does not eliminate the possibility of rabies.

Question: What are the signs and symptoms of rabies?
Incubation period of 12–700 days with an average of 20–90 days. Initial signs and systems are fever, headache, malaise, anorexia, sore throat, nausea, cough, and pain or paresthesias at the bite site.
In the CNS stage, agitation, restlessness, altered mental status, painful bulbar and peripheral muscular spasms, bulbar or focal motor paresis, and opisthotonos are exhibited. As in the Landry-Guillain-Barré syndrome, 20% develop ascending, symmetric flaccid and areflexic paralysis. In addition, hypersensitivity to water and sensory stimuli to light, touch, and noise may occur.
The progressive stage includes lucid and confused intervals with hyperpyrexia, lacrimation, salivation, and mydriasis along with brainstem dysfunction, hyperreflexia, and extensor planter response.
Final stages include coma, convulsions, and apnea, followed by death between the fourth and seventh day for the untreated patient.

Question: What is the diagnostic procedure of choice in rabies?
Fluorescent antibody testing (FAT).

Question: How is rabies treated?
Wound care includes debridement and irrigation. The wound must not be sutured; it should remain open. This will decrease the rabies infection by 90%. RIG 20 IU/kg, half at wound site and half in the deltoid muscle, should be administered along with HDCV, 1 mL doses IM on days 0, 3, 7, 14, and 28, also in the deltoid muscle.

Describe the intracorporeal dissipation of the rabies virus:
The virus spreads centripetally up the peripheral nerve into the CNS. The incubation period for rabies is usually 30–60 days with a range of 10 days to 1 year. Transmission usually occurs via infected secretions, saliva, or infected tissue. Stages of the disease include upper respiratory tract infection symptomatology, followed by encephalitis. The brainstem is affected last.

Question: What animals are the most prevalent vectors of rabies in the world? In the United States?
Worldwide, dog is the most common carrier of rabies. In the United States, the skunk has become primary carrier. In descending order, bats, raccoons, cows, dogs, foxes, and cats are also sources.

Question: What would you expect to find in the hippocampus of a patient with rabies?
Negri bodies. Incubation for rabies is 30–60 days. Treatment includes cleaning of the wound, rabies immune globulin, and human diploid cell vaccine. Remember, half the rabies immune globulin goes around the wound; the other half goes IM.

Question: Since 1980, how many individuals in the United States have survived from rabies without postexposure prophylaxis?
None, it is 100% fatal.

Question: What is the etiology of roseola infantum?
It is a virus caused by the herpes virus 6 or 7.

Question: What are the hallmark features of the virus?
High spiking fevers up to a week followed by a rose-pink maculopapular rash.

Question: What is some other physical examination characteristics associated with roseola?
Pharyngeal and tonsillar injection without exudates, and lymphadenopathy.

Question: Is there a specific treatment for this virus?
No. Supportive care and treatment of the fever with acetaminophen is appropriate.

Question: What are the two types of rubella?
Rubella (German measles) and congenital rubella syndrome.

Question: How is the virus spread?
Through respiratory droplets and through the placenta in congenital rubella syndrome.

Question: Name some potential congenital defects as a result of rubella:
Patent ductus arteriosus, cataracts, deafness, and mental retardation.

Question: At what stage are these defects more likely to occur in pregnancy?
In the first trimester.

How would you test for congenital rubella syndrome in a pregnant woman?
The presence of IgM antibody indicates a recent infection. Amniocentesis analysis can detect if the virus is in the fluid.

Question: What measure can be taken for preventing rubella?
Vaccination of the rubella live attenuated virus.

Question: What is the characteristic of a rash caused by measles?
It is a maculopapular rash.

Question: How is the virus transmitted?
Respiratory droplets from coughing and sneezing.

Question: Which vitamin deficiency will cause a worsening of the measles virus?
Vitamin A.

Question: What are some prodromal signs and symptoms that present with measles?
A course of 10–14 days will start a presentation of fevers, conjunctivitis, coryza, and coughing. The hallmark of Koplik spots will reveal themselves on the buccal mucosal surface.

Question: What are Koplik spots?
The are bright-red lesions with a white central dot on the buccal mucosa.

Question: Name some complications of measles:
Encephalitis, pneumonia, and otitis media.

Question: Describe the signs and symptoms of varicella (chicken pox):
Onset of varicella rash 1–2 days after prodromal symptoms of slight malaise, anorexia, and fever. The rash begins on the trunk and scalp, appearing as faint macules and later becoming vesicles. Remember, dew drops on a rose petal appearance.

Question: What is zoster?
Zoster is the recurrent infection of the Herpes virus. This virus will break out commonly in a single dermatome and begin with pain to the dermatome, followed by a vesicular, red-bordered rash that will crust over a 14-day period. Postherpetic neuralgia is a potential long-term complication.

Question: What is the most reliable method for diagnosing varicella-zoster?
In a majority of cases the diagnosis is made clinically.

What is the treatment in immunocompetent children and in adults?
In children, no treatment is necessary, only supportive care.
In adults, course of acyclovir for varicella to reduce the course of the virus. In zoster, famciclovir and valacyclovir can be used.

Question: Which patients are recommended to receive the varicella vaccine and the zoster vaccine?
Varicella—children aged 1 to 12 years.
Zoster—adults older than 60 years.

Question: What is the typical clinical presentation of progressive multifocal leukoencephalopathy (PML)?
PML commonly presents with focal neurological signs such as hemisensory or motor signs, and visual field deficits.

Question: Which virus is responsible for causing PML?
JC virus, which is a papovavirus that infects oligodendrocytes.

Question: PML is seen in which other immune disorders?
Cell-mediated immune deficiency. It is thus seen in HIV disease, chronic myeloid leukemia, Hodgkin disease, chemotherapy patients, and rarely sarcoidosis.

Question: What are the common radiological features of PML?
Hypodensities in the subcortical white matter on the CT scan. T1 images on the brain MRI are hypointense and T2 images are hyperintense. They are nonenhancing and usually start in the parietooccipital region of the subcortical white matter.

Question: Which virus is considered responsible for tropical spastic paraparesis (TSP)?
Human T cell lymphotrophic virus type 1.

Question: What are the modes of transmission of HTLV 1?
Vertical: mother to child. Horizontal: through sexual contact and blood transfusion.

Question: To which group of viruses does the poliovirus belong?
Poliovirus is an enterovirus that belongs to the picornavirus group.

Question: What are four other infectious causes of paraparesis?
Syphilis, tuberculosis with Pott disease of the spine, leptospirosis, and VZV.

Question: What is epidemic pleurodynia (Bornholm disease)?
An upper respiratory tract infection followed by pleuritic chest pain and tender muscles. Coxsackie viruses are a group of enteroviruses responsible for the epidemic myalgia (Bornholm disease) where pleurodynia is also a common feature. Specifically, the disease is thought to occur due to a Coxsackie group B virus.

What is the cerebral spinal fluid (CSF) characteristic of polio?
In the acute stages, it is associated with a lymphocytic pleocytosis, elevated protein, and normal glucose. There may be a neutrophilic response very early in the disease. Chronic residual polio has normal CSF.

Question: What is the cause of epidemic keratoconjunctivitis?
Adenovirus.

Question: What is the most common cause of foodborne viral gastroenteritis?
Norwalk virus commonly found in shellfish.

Question: What is the Jarisch-Herxheimer reaction?
Headache, fever, myalgia, hypotension, and an increased severity of syphilis symptoms that occurs after taking benzathine penicillin G for the treatment of syphilis. The reaction may result in neurological, auditory, or visual changes.

Question: How should a patient with a black widow spider bite be treated?
Consider antivenin, IV calcium gluconate, and IV opiates plus IV benzodiazepines.

Question: How should a jellyfish sting be treated?
Rinse with saline. Apply 5% acetic acid (vinegar) locally to the wound for approximately 30 minutes. In addition, corticosteroid agents may be applied topically. No antibiotics are necessary. Tetanus prophylaxis.
Chironex fleckeri antivenin only for this coelenterate.

Question: What is the differential diagnosis of a ring lesion on CT scan?
Toxoplasmosis, lymphoma, fungal infection, TB, CMV, Kaposi sarcoma, and hemorrhage.

Question: Name four enterotoxin-producing organisms that can cause food poisoning:
1. Clostridium
2. Staphylococcus aureus
3. Vibrio cholerae
4. E. coli

Question: What is the most common presentation of cryptococcosis?
Fungal meningitis with Cryptococcus neoformans.

Question: What prophylactic medication would you recommend to a patient traveling to Costa Rica?
Mefloquine, 250 mg, once a week. Treatment should begin 1 week before travel and continue 6 weeks after returning. Mefloquine, not chloroquine, is now the drug of choice due to the resistance of chloroquine in some regions. Check with the CDC for specific information.

What preventive measures would you recommend to a patient planning a trip to Mexico?
Avoidance of water, ice, foods prepared in water, and raw or prepeeled fruits and vegetables. Prophylactic antibiotics are not routinely recommended. However, if they are a necessity, ciprofloxacin is the drug of choice. Otherwise, treatment with antibiotics should begin with the onset of symptoms, as should rehydration.

Question: A friend is headed to Benin on the west coast of Africa. What immunizations and prophylactic treatments must she receive before departing?
Hepatitis A vaccine
Oral polio vaccine
Tetanus-diphtheria vaccine
Live oral typhoid vaccine
Measles vaccine
Yellow fever vaccine
Mefloquine prophylaxis for malaria

Question: At what concentration is ozone damaging to your health?
10 ppm. Initial effects are tearing, pulmonary edema, and pain in the trachea.

Question: Which immunizations do healthy senior citizens need?
Tetanus booster every 10 years, influenza vaccination every year, and a pneumococcal vaccination.

Question: Which vaccine should be administered to postsplenectomy patients?
Pneumococcal vaccine.

Question: What five vaccines should be administered to adults?
1. Hepatitis B vaccine: Give to high-risk patients (health care workers, homosexuals, and IV drug users)
2. Influenza vaccine: Give annually to elderly patients and patients with chronic illnesses
3. MR: Give to all patients without immunity (most often required by school institutions)
4. Pneumococcal vaccine: Give once to patients older than 65 years and patients with chronic illnesses
5. Tetanus/diphtheria: Give all adults a primary series and a booster every 10 years

Question: Other than immunocompromised patients, who should not receive live vaccines?
Pregnant women. Oral polio vaccine should be avoided in anyone in close contact with an immunocompromised person because of the virus’s ability to spread.

Question: A patient comes in for vaccinations and has a URI and a fever of 37.5°C. Can you administer vaccines to this patient?
Yes. URI or gastrointestinal illness is not a contraindication to vaccination. Fever may be as high as 38°C and the vaccine still administered. Likewise, use of antibiotics or recent exposure to illness is not a reason to delay vaccination.

When administering the Mantoux skin test to a person with HIV, what induration indicates a positive reaction?
>5 mm. In individuals with risk factors for TB, induration must be >10 mm. For those with no risk factors, induration must be >15 mm to be positive.


REFERENCES
Fauci AS, Braunwald E, Kasper DL, et al., eds. Harrison’s Principles of Internal Medicine, 17th ed. New York: McGraw-Hill; 2008. http://www.accessmedicine.com
Hall JB, Schmidt G, Wood LD. Principles of Critical Care. 3rd ed. New York, NY: McGraw-Hill; 2005.
Levinson W. Review of Medical Microbiology and Immunology. 10th ed. New York, NY: McGraw-Hill; 2008.
McPhee SJ, Papadakis MA, eds. Current Medical Diagnosis and Treatment 2009. New York, NY: McGraw-Hill; 2009.
McPhee SJ, Ganong WF. Pathophysiology of Disease—An Introduction to Clinical Medicine. 5th ed. New York, NY: McGraw-Hill; 2006.