API stands for Application Programming Interface, i.e. API is the way for an application to interact with certain system/application/library/etc. For example, there are API's for OS (WinAPI), API's for other applications (like databases) and for specific libraries (for example, image processing), etc.
Acute HIV infection: The first stage of HIV, known as the primary or acute infection, may cause symptoms of fever and skin rash. This is because the virus is multiplying rapidly in the body and infecting immune cells. This phase generally lasts several weeks.
Yellow fever is caused by the yellow fever virus (YFV), also called Flavivirus. The virus is transmitted by female mosquitos, who pick it up from monkeys or other humans, then delivers it to a new human when they bite and suck blood. The disease cannot be spread from person to person.