Question A: West Nile virus, an emerging encephalitis infection, was first seen in New York in 1999. It mostly affects birds but can also infect humans and horses. Although most human cases of West Nile disease are subclinical, there can be severe infection and rapid death in the elderly. Mosquitos are the vectors for this disease.
Question B: Spraying is often used to control mosquito linked disease outbreaks.
Question C: People whose work involves horses have more contact with the mosquitos.
Question D: You need to point out to the jogger that air travel is now very frequent and mosquitos can be transported in planes by accident. Also the weather in the US in changing, and warmer, moister conditions favor the growth of mosquito populations.
Question A: The use of immunosuppressive drugs leads to immune compromise and opportunistic infections. One of the more common opportunistic infections is caused by the fungus Cryptococcus. Symptoms include intermittent headache, dizziness, and difficulty with complex cerebral functions, and these symptoms continue over a period of weeks or months. Seizures, cranial nerve damage, and papilledema (edema of the optic nerve) appear in the later stages of the infection, accompanied by dementia and decreased levels of consciousness.
Question B: The possibility that the infection was transmitted via the transplant is there but unlikely, since kidney screening previous to transplant is thorough. He is probably still on immunosuppressive drugs. Therefore he is immune compromised and susceptible to opportunistic infection.