Mosquitoes are the most dangerous creature on Earth, responsible for causing more human deaths per year than any other animal. These tiny insects don’t rely on brawn or venom to slay their victims; instead, they kill those they bite by injecting deadly pathogens into their bloodstream. Malaria, Chikungunya, Zika, Yellow fever and Dengue fever are just some of the potentially life-threatening illnesses that can be transmitted to humans through mosquito bites. But one notorious virus, in particular, has people especially worried, and that’s HIV.
This bloodborne virus is usually passed from human to human via sexual activity or sharing of needles, but can a mosquito give you HIV? Mosquitoes ingest the blood of people they bite, so could a mosquito that has fed on someone with HIV pass the virus along to their next host?
Can you get HIV from a mosquito bite?
The answer, fortunately, is no, a mosquito cannot give you HIV. The HIV virus cannot be spread from person to person via the bite of an infected mosquito.
This is because the mosquito has several physiological and biological features that make it impossible for the virus to survive or be transmitted once it’s been swallowed.
But exactly what is it that renders the mosquito incapable of transmitting HIV?
Why can’t mosquitoes transmit HIV?
The HIV virus can’t survive the insect gut
The HIV virus finds its way inside a mosquito when it is ingested as part of a blood meal. Once swallowed, it winds up in the insect gut along with the rest of the food. Already, this is game over for the HIV virus, because it can’t replicate under these conditions.
HIV is a retrovirus, which means it cannot reproduce without first entering a host cell. Once inside, it integrates its own DNA into the DNA of the host cell, which allows it to replicate.
In human blood, HIV targets a type of white blood cell known as CD4 (or T-helper) cells. The virus is dependent on these cells to survive, as it can’t replicate unless it can first attach itself to, then enter, a CD4 cell.
Unfortunately for the HIV virus, there are no CD4 cells in the insect gut. In this environment, there is no way for the virus to replicate or move to other parts of the insect’s body. For a virus to be transmitted by mosquitoes, it must find its way into the salivary glands of the insect. However, the HIV virus is quickly digested along with the blood meal and is completely broken down in the process.
Mosquito mouthparts make transmission impossible
That pointy bit on the front of a mosquito is actually a highly specialized tool for piercing the skin and sucking blood. It may look like one, long needle, but these intricate structures are actually comprised of six different mouthparts. Of these, four are used to slice away at the skin, while the other two function as tubes. One of these tubes injects saliva into the host’s bloodstream while the other sucks blood up into the insect’s belly. This means that only the saliva of the mosquito ends up in your blood when you get bitten, as this sophisticated structure makes it physically impossible for the insect’s last meal to enter your blood.
Once the HIV virus enters the insect gut, it is quickly digested before it gets the chance to find its way into the insect’s salivary glands. This means that the saliva injected by a mosquito bite is guaranteed to be HIV-free.
Only very low levels of the HIV virus circulate in human blood
It is impossible for mosquitoes to spread HIV, thanks to the structure of their mouthparts and the unfriendly conditions inside the insect gut. Even if they were capable of transmitting small amounts of blood between hosts, the chances of contracting HIV this way would virtually nonexistent.
This is because the HIV virus circulates in the blood only at low levels. This means the amount of blood transported by a mosquito wouldn’t contain anywhere near enough to infect someone new. In fact, to contract the virus this way you would have to be bitten a whopping ten million times by mosquitoes that had recently fed on an HIV carrier.
How can you stop mosquitoes from biting you?
Although mosquitoes aren’t capable of spreading the HIV virus, they are known to transmit a wide range of potentially deadly diseases to humans. Yellow fever, Dengue and Plasmodium (the parasite that causes malaria) are all pathogens capable of breeding inside the insect gut. From here, they can enter the salivary glands, and are passed on to humans via the bite of an infected mosquito.
The best way to avoid getting sick (especially in tropical regions) is to try to prevent mosquito bites altogether. Keep mosquitoes off you by:
- Wearing long, loose-fitting clothing (especially during the evening time).
- Applying bug spray (preferably containing DEET of picaridin) regularly.
- Sleeping under a mosquito net.
- Using fans and other mosquito repellents (such as reed diffusers or aerosol sprays) around your home.
- Install screens around windows and doors.
Mosquito bites are a nightmare for many reasons. They’re itchy, easily infected, and potentially life-threatening if delivered by a mosquito that’s carrying a deadly pathogen. Mosquitoes are notorious vectors for a wide range of dangerous diseases, including malaria, Zika, and Dengue fever. One question asked again and again, however, is: can mosquitoes spread HIV?
Despite their talent for transmitting diseases, mosquitoes are not capable of passing the HIV virus from host to host. The conditions inside the mosquito gut mean the HIV virus is digested shortly after feeding and has no opportunity to enter the salivary glands.
On top of this, the unique structure of the mosquito’s mouthparts means that only saliva is injected into the host during feeding. Any blood remaining in the insect’s gut from their last meal stays right where it is and is broken down – along with any HIV virus it may be harboring.