Why would these symptoms be attributed to something acquired rather than to something inherited?

Four friends who lived in different states gathered annually for a weeklong elk-hunting trip in Montana for more than 20 years. As part of their tradition, they shared a meal of one of the harvested elk. One of the four was killed in a one-vehicle automobile accident a year ago when he apparently experienced a sudden seizure at highway speeds. Autopsy concluded that the cause of death was due to trauma, but also revealed pronounced spongiform encephalopathy and the presence of significant amyloid plaques in the brain tissue. Most recently the remaining three have developed similar patterns... Show more

Four friends who lived in different states gathered annually for a weeklong elk-hunting trip in Montana for more than 20 years. As part of their tradition, they shared a meal of one of the harvested elk. One of the four was killed in a one-vehicle automobile accident a year ago when he apparently experienced a sudden seizure at highway speeds. Autopsy concluded that the cause of death was due to trauma, but also revealed pronounced spongiform encephalopathy and the presence of significant amyloid plaques in the brain tissue.
Most recently the remaining three have developed similar patterns of memory loss, pronounced personality changes, problems with their ability to balance themselves, and some speech difficulties, and two of them have experienced seizures and depression. This latter issue was initially attributed to the loss of their close friend, but it now appears to be something quite different, but still related to something they all acquired on at least one of their hunting trips. Their physicians are beginning to suspect that the root cause is variant Creutzfeldt-Jacob disease (vCJD). Show less