Here’s an interesting little tidbit: mosquito saliva is bad for you. It has long been known that various viruses, including malaria and west nile virus, are spread by mosquitos; the virus resides in the mosquito’s mouth parts and is injected into the host during a bite. But scientists have recently discovered that exposure to uninfected mosquito saliva can alter the course of subsequent infection. A case of west nile virus is much worse in animals that have been bitten by “clean” mosquitos (those not carrying the virus) in the recent past. Here’s a great reason to wear your bug repellent all the time!