The Myth of Mosquitoes

In not wanting to contribute to the myth, allow me to be clear: mosquitoes cannot transmit HIV! However, with many other viruses transmitted this way, have you ever wondered why?

There are three main ways in which a mosquito could be thought to transmit HIV; however knowledge of some key facts makes these methods of transmission near impossible.

The first potential path of transmission involves a mosquito feeding on someone living with HIV, the virus surviving the mosquito’s digestive system, then increasing in numbers within its blood and spreading into the mosquito’s saliva. Transmission would then apparently occur when the mosquito bit someone not living with HIV, causing infection when injecting its infected saliva directly into their bloodstream. The other ways people guess HIV could be transmitted involve a mosquito being interrupted whilst feeding on someone living with HIV and then resuming its feed on an HIV-negative individual. Transmission could then potentially occur when the bite wound becomes exposed to infected blood either left on the mosquito’s mouthparts or from a smearing of blood resulting from squashing the mosquito.

One reason why these transmission scenarios do not occur is that HIV does not survive long outside the human body. Unlike mosquito-transmitted viruses like Malaria, HIV is incapable of surviving and thriving within a mosquito. Even when scientists bypass the digestive system and place the virus directly into a mosquito’s bloodstream, HIV does not survive or infect a mosquito’s saliva. Another reason why mosquitoes can’t transmit HIV, as humorously written by a researcher, is because mosquitoes are not flying syringes! Unlike a syringe, mosquitoes have two separate, one-directional mouth passages, one for the exit of saliva and the other to draw up blood. The passageway that carries blood into a mosquito’s gut is never flushed out, blood flow is always away from the bite victim. The final reason why HIV is not transmitted by mosquitoes relates to the transmission of HIV requiring not only exposure to the virus, but exposure to enough of the virus to cause infection. Since HIV circulates at very low levels in human blood when compared to the levels at which all known mosquito-carried viruses circulate, mosquito transmission is considered highly improbable.

So there you have it, fingers crossed that when asked at the next Pop Quiz ‘can mosquitos transmit HIV?’, you can give a most thorough answer and receive bonus points!