KnowHOW team explains: When a mosquito bites a malaria patient, it sucks in the malarial parasite from the blood. The germ reaches the stomach of the mosquito, but it does not get digested there. Instead, it pierces the gut wall, moves into the cavity, multiplies there twice or thrice, and ultimately reaches the salivary gland of the creature.

A chemical in the saliva prevents the blood from clotting. Hence, while biting, the mosquito injects a little saliva first. When the same mosquito bites a healthy person, the malarial parasite enters the person’s body along with saliva. This is how mosquitoes spread germs in many cases. But in case of HIV spreading the microbe isn’t so easy.

All viruses are very susceptible to changes in temperature and adverse environmental conditions, and HIV is no exception. When a mosquito bites a person having AIDS, the HIV enters the mosquito’s stomach, but it is destroyed within seconds. So, by the time the mosquito has a second blood meal, there are no longer any infective virus in it.

As the HIV gets no chance to migrate to the salivary gland of the mosquito, it is impossible for the virus to spread through its bite to a new person in any way.

The question was sent by Shankar Giri from Rajgangpur, Orissa