A mosquito sitting on human skin, colored with a blue overlay.

Can Mosquitoes Transmit HIV?

It’s well known that mosquitoes are carriers for infections viruses, but can mosquitoes transmit HIV? In this blog, we’ll break down this common misconception about mosquitos and HIV symptoms and answer that question.

Mosquitoes are notorious for spreading more than a few dangerous infections, most notably malaria and the West Nile and Zika viruses, though that’s only a short list of the dangerous viruses and infections they can transmit. Mosquitoes, by way of the viruses they transmit, are responsible for killing more people per year than any other animal.

However, while the threat of contracting a dangerous virus from a mosquito is certainly credible, fortunately, HIV is not one of those viruses. Multiple studies have shown no evidence of the possibility of HIV transmission from mosquitoes, especially in countries with high rates of HIV and large unchecked mosquito populations.

Here are a few reasons why mosquitoes cannot transmit HIV from person to person.

HIV is not as present in the blood as other viruses

Mosquitoes are able to spread certain diseases from person to person, in part, because these diseases are often circulating at very high levels in human blood. This means that there is a greater chance of the blood being drawn in by the mosquito carrying the virus or disease. However, with HIV, the virus circulates in such extremely low levels in the blood that it is physically impossible for one mosquito (or any number less than 10 million mosquitoes, according to a Rutgers University study) to carry enough HIV-positive blood to cause a new infection.

Mosquitoes do not pass blood from one host to another

Another common reason people worry about the potential for mosquitoes to transmit HIV comes from a mental comparison between the risk of sharing needles and the needle-like mechanism that mosquitoes use to bite and draw blood. In reality, mosquitoes have a system of six different mouthparts, not one needle-like mechanism. Some of these mouthparts are used to pierce the skin of the person or animal. Two of the mouthparts operate as tubes, with one tube being used to draw blood out of the host and the other being used to inject the mosquito’s saliva into the host. The mosquito’s saliva contains a small amount of anticoagulants for the express purpose of allowing the mosquito to feed more efficiently. No blood that a mosquito has previously ingested makes its way into a host, meaning that a mosquito that draws blood from a person with HIV can not expose another person to that blood. To compare the virus with malaria, after incubating in the mosquito, malaria can migrate to the mosquito’s salivary glands. When a mosquito carrying malaria bites another host, the malaria is transmitted to the host through the mosquito’s saliva.

Sharing a needle that has been used by a person with HIV is different. Blood is always introduced into the needle and the syringe when making any kind of injection, so using a needle that someone with HIV has used poses the risk of some of the blood in the needle or syringe being passed to another person. The quantity of blood introduced to the needle and syringe is much larger than that in a mosquito, and the HIV virus can survive in the hermetically sealed environment of a needle and syringe for nearly 4 weeks.

HIV cannot survive inside mosquitoes

Another reason why mosquitoes cannot transmit HIV is that the virus cannot replicate in their system. If a mosquito draws blood that contains the HIV virus, the virus is broken down inside the mosquito. The HIV virus requires human T cells to replicate, and mosquitoes do not have T cells. This also applies to other insects that draw blood, including fleas, bed bugs and lice. HIV cannot replicate inside these insects, so it cannot survive.

HIV requires specific conditions for transmission

In short, there are several conditions that must be met in order for HIV transmission to occur. The virus requires a route by which it can enter the body, namely, through exposure to mucous membranes or direct blood-to-blood contact through a fluid in which the virus can replicate, such as blood, semen or breast milk. It cannot be spread through skin-to-skin contact and the virus cannot replicate or be stored in saliva, urine or feces. In addition to these conditions, the viral load in both the person who is HIV positive and the fluid transmitting the virus must be high enough to potentially result in an infection. With these stipulations, the risk of HIV transmission through mosquito bites is largely considered impossible.