Collective intelligence and wisdom of “The Straight Dope” I have a question that made me think for quite a while. Please give scientific based answer if you have, or provide me with direction, if known, where to find data.
My question is:
“Is it possible to be infected with HIV, if a mosquito bites a HIV-positive person and then bites you (taken prior to the bite you where HIV-negative)?
And if not, why so?”
Thank you in advance
Thank you 
I hate Google’s refined and “personally tailored” search results, because almost never the found results are the one I was looking for.
My understanding is you can catch HIV from a mosquito, but only if …
… it fucks you in the ass.
Otherwise, no, you cannot. You can read why here.
Simply put, a single mosquito won’t bite two people one right after the other-- There’s a delay of over a day, which is far longer than the virus can survive under those conditions.
Mosquitoes carry malaria, but thelife cycleof the malaria-causing organism is quite complex. It’s not an idiot like HIV…
(The teacher for my first year of high school biology had just taken a parasitology course & we learned a bunch of “interesting” stuff.)
I have personally observed the same mosquito bite two people within the space of a few seconds on numerous occasions.
While it may be true that a mosquito takes a considerable time to digest a full blood meal, the reality is that a mosquito almost never obtains a full blood meal from a single feeding session. They are almost always disturbed within a second or so.
If what you say is true then mosquitoes would almost never be able to complete their life cycle before they died of old age, since they would have to obtain a fraction of the required blood, then wait a day, then obtain another fraction, then wait a day wait a day and so on, possibly for weeks on end.
The reality is that a disturbed mosquito will attempt to feed again almost immediately. If two people are close together, it will feed on either of them.
Not only this but the dengue virus is spread from person to person by mosquitos
The mosquito does not inject blood when it bites. It injects saliva, which come from a gland, not the stomach. Any disease has to make its way from the stomach to the salivary glands. Mosquito-borne diseases have evolved to make this journey, but they are all caused by non-viruses. HIV is too simple for such a complex task, and since it dies very quickly outside a host, it’s going to be dead before it can migrate.
Dengue is caused by a virus, so at least one virus can make it.
In any case I was responding to the claim mosquitos only bite once in a lifetime, thats just wrong.
HIV isn’t a parasite that can be transmitted by mosquitos. Dengue fever and malaria are. As the article Karl Gauss** linked to says.
How do you tell them apart? They all look alike to me.
Not going to get into the rest, but this is wrong.
Malaria is caused by a parasite, any one of various species of Plasmodium.
Dengue fever, yellow fever, west nile virus, and quite a few important equine diseases are spread by mosquitoes (plus any I may have not committed to memory). They are all caused by viruses, and not only that, but they are not all within the same family. IirC, the general term for these viruses is arbovirus, but any arbovirus may come from different viral families.
And of course, HIV is in the family of retroviruses, which, IIRC, does not contain any mosquito-transmitted disease.
The people? Name tags can help.
The mosquitoes? If it’s within a period of a few seconds, you can just visually track them. They’re not particularly fast.
Correction, there is one animal retrovirus that could potentially be transmitted by mosquitoes, but it is not the likely mode of transmission. And that disease is not as closely related to HIV as it is related to other retroviruses.
I appreciate the correction. My meaning is that there are things that can live in a mosquito and things that aren’t adapted to that.
********This is the most frequent question I get in my professional capacity.
No, HIV is not transmitted by mosquitoes. It was actually a concern in the early days when we didn’t have much knowledge of the biology of the virus, but all laboratory experiments were a resounding NO. Also, the epidemiology of infection would be very different if there was a vector-mediated transmission component.
Mosquitoes are not flying syringes. There is a lot of very complicated biology that must occur for a particular mosquito to be capable of transmitting a particular pathogen (I am going to use virus for the examples, but all these points are equally valid for any vector-borne pathogen, virus or otherwise).
After imbibing the virus in an infected bloodmeal, the virus must bind to the correct receptor on the midgut epithelial cell layer so that it can enter the gut cells. If the receptor isn’t there, the virus won’t infect the gut and will be digested away along with the blood. Result – No transmission.
If the correct receptor is present, and the virus infects the gut cells, it has to be able to replicate in the cell. If it can’t, the infection stops there. Result – No transmission.
If the virus is able to replicate in the gut cells, it has to then exit the gut and enter the open circulatory system of the mosquito. The gut is encased in a sheath called the basal lamina – the virus has to escape the cell and pass through the basal lamina (we don’t actually have a good idea how this occurs). If it can’t, the virus stays trapped in the gut and the infection stops there. Result – No transmission.
(as an aside, in some mosquitoes, the virus can’t infect/escape the gut, so the mosquito can’t transmit, but if you bypass the gut by injecting the virus directly into the body cavity, the process will continue)
If the virus can escape the gut, it has to then infect the other body tissues to amplify in titer. If it can’t, the infection stops there. Result – No transmission.
After amplification, the virus has to bind to the proper receptor in the mosquito salivary glands, just like in the gut. At least for malaria, the receptor on the salivary glands is different from the one in the gut (we don’t have a good idea what the receptors are for viruses yet). If the receptor isn’t there, the infection stops. Result – No transmission.
After entering he cells of the salivary glands, the virus needs to be able to replicate in those cells. If it can’t, the infections stops there. Result – No transmission.
If the virus can replicate in the salivary glands, it then has to exit the gland and be secreted into the saliva. If it can’t, the infection stops there. Result – No transmission.
If the virus is secreted into the saliva, it will be inoculated into the mosquitoes’ next host during a bloodfeed. Result - TRANSMISSION.
This process takes days to weeks depending on the mosquito, the pathogen, and ambient temperature.
HIV FAILS AT STEP 1. There is no receptor for HIV in the mosquito gut. If you bypass the gut by injecting it into the mosquito, it doesn’t replicate or infect the salivary glands. The entire biology is wrong.
Mosquitoes do not transmit HIV.
While what you say here may be true for HIV, it isn’t true for “any vector-borne pathogen”.
There are any number of pathogens that are transferred mechanically on the mouthparts of mosquitoes and other arthropods. Myxomatosis is the most well-studied of these pathogens because of its economic importance, but there are a great many others, including bacterial and protozoal diseases.
These diseases are all spread by the infective particle adhering to the mouthparts of the arthropod. There is no complicated biology involved in the transfer as far as anyone can tell. The microbe is simply in the plasma/blood that adheres to the arthropod’s mouthparts. When the liquid dries, the virus survives. When the arthropod feeds again the virus is mechanically dislodged and literally falls into the tissues of the hist.
It’s worth noting that all these diseases, AFAIK, are characterised by epidermal lesions and swellings with high pathogen concentrations. So the virus presumably evolved to produce symptoms that would aid in mechanical transmission. By having such high concentration directly under the skin the chances of some particles adhering to the mouthparts is increased radically.
These viruses are also fairly robust, unlike the fragile HIV.
Nonetheless, there are numerous vector borne pathogens that are transmitted by parasitic arthropods through purely mechanical means. No complicated biology is involved, and no binding with the gut of the vector. This is why these diseases are able to spread effectively worldwide, regardless of whether a specific vector is present. Myxomatosis, especially, has been shown to be transmitted by almost any athropod that feed on blood or lymph; fleas, ticks, lice, mites, flies mosquitoes etc. By retaining a strictly mechanical transmission modes, these viruses have avoided becoming dependent on any specific vector for transmission.
True, I was simplifying a bit as the question was on HIV (and myxo doesn’t infect humans anyway). I didn’t want to get into the details of mechanical vs propagative vs cyclopropagative vs cyclodevelopmental vectorborne pathogen transmission.
I had a friend whose mother was a nurse in a rural are in Northern Natal in the 1980s and she was convinced that the answer to your question is yes as she found whole families who were HIV including young children who were born before the parents contracted the disease.