Malaria

I don't think I really have to explain malaria to you, but there are a few little things which are germane.

Malaria prophylaxis provides very little actual protection against malaria. If you do come down with malaria, the treatment's just a really huge dose of the prophylaxis, so a lot of people think it's rather silly. The side effects of chloroquine (the most popular after Lariam was taken off the market) are very annoying: disorientation, hallucinations, dizziness. As a result, very few archaeologists actually take prophylasis.

Hallucinations aren't fun, guys.