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Do we know why mosquitoes do not transmit the HIV-AIDS virus?

by daniel6874
Tags: hivaids, mosquitoes, transmit, virus
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daniel6874
#1
Jun12-10, 09:32 AM
P: 64
Do we know why mosquitoes do not transmit the HIV-AIDS virus?
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Rajini
#2
Jun12-10, 10:01 AM
P: 600
hi,
have a look here..
http://www.rci.rutgers.edu/~insects/aids.htm
daniel6874
#3
Jun12-10, 01:58 PM
P: 64
Quote Quote by Rajini View Post
This is an interesting article but the theoretical impossibility of transmission would also apply to the virus that causes yellow fever. Not all viruses are alike, but there is no indication why the AIDS virus would be any less transmissible than other mostquito-borne viruses.

I completely accept that AIDS is not mosquito-transmitted. I just don't understand what sets the AIDS (retrovirus, I think) pathogen apart from other nm-sized organisms. Thanks.

Ygggdrasil
#4
Jun12-10, 02:10 PM
Other Sci
Sci Advisor
P: 1,384
Do we know why mosquitoes do not transmit the HIV-AIDS virus?

Yellow fever is able to infect mosquito cells and replicate inside of mosquitoes, an ability that HIV has not evolved. Perhaps this has to do with the fact that HIV infects a much more specific class of cells than yellow fever.
Proton Soup
#5
Jun12-10, 03:41 PM
P: 1,070
Quote Quote by Rajini View Post
it is the second mechanism that seems to be an unknown. how would you go about proving this?
daniel6874
#6
Jun13-10, 10:56 AM
P: 64
Quote Quote by Proton Soup View Post
it is the second mechanism that seems to be an unknown. how would you go about proving this?
"2. In the second mechanism, a mosquito would ...feed on an HIV carrier and be interrupted after it had successfully drawn blood. Instead of resuming...on its original host, the mosquito would select an AIDS-free person to complete the meal.... equine infectious anemia is transmitted to horses by biting flies in this manner."
____

I don't understand what you are suggesting should be proved. The article says these mechanisms are used in other settings and not used in HIV transmission. We don't have to prove it--it doesn't happen. I gather that this mechanism has been shown in equine anemia context. Sorry if I am misunderstanding your question.
Proton Soup
#7
Jun13-10, 11:31 AM
P: 1,070
Quote Quote by daniel6874 View Post
"2. In the second mechanism, a mosquito would ...feed on an HIV carrier and be interrupted after it had successfully drawn blood. Instead of resuming...on its original host, the mosquito would select an AIDS-free person to complete the meal.... equine infectious anemia is transmitted to horses by biting flies in this manner."
____

I don't understand what you are suggesting should be proved. The article says these mechanisms are used in other settings and not used in HIV transmission. We don't have to prove it--it doesn't happen. I gather that this mechanism has been shown in equine anemia context. Sorry if I am misunderstanding your question.
how do you know that?
AlexB2010
#8
Jun13-10, 12:09 PM
P: 39
Quote Quote by Proton Soup View Post
how do you know that?
In theory mosquitoes can be capable of transmit HIV, if you look really deep probably you can find a rare case were this happens. One evidence that this are not common is the epidemiological data of African countries, if this kind of transmission occurs the epidemic data will be far more worst.
nismaratwork
#9
Jun13-10, 12:17 PM
P: 2,284
This is very clear, from the epidemiology alone, and from basic biology. To ask this shows a fundamental lack of understanding as to how insect-borne disease DOES find a transmissible intermediary.

Quote Quote by Staf.ord
Ways in Which HIV Is NOT Transmitted
Insect bites
HIV is not transmitted by mosquitoes, flies, ticks, fleas, bees or wasps. If a bloodsucking insect bites someone with HIV, the virus dies almost instantly in the insect's stomach (as it digests the blood). HIV can only live in human cells.

Mosquitoes cannot transmit HIV for two reasons:

•The mosquito draws blood and injects saliva. The blood from one person is not injected into the mosquito's next victim.
•HIV dies in the mosquito's body. People sometimes are confused because malaria actually reproduces inside the mosquito's digestive tract, using the insect as part of its life cycle. HIV does not.
These facts are confirmed by looking at infection patterns. In areas where mosquitoes are common and where HIV is prevalent, the distribution of AIDS cases in the population is not different from other areas. If mosquitoes transmitted HIV, they would be seeing a disproportionate number of children and elderly infected in those areas.
http://www.sfaf.org/aids101/transmission.html

Here is some research that will allow you to understand which insects make proper vectors for disease, and further research can explain why: http://www.cals.ncsu.edu/course/ent4...anvectors.html

I doubt you could find a single case of mosquito-borne HIV that you could possibly confirm, however close you look. HIV requires more than a single virion to cause infection.
Proton Soup
#10
Jun13-10, 12:32 PM
P: 1,070
Quote Quote by AlexB2010 View Post
In theory mosquitoes can be capable of transmit HIV, if you look really deep probably you can find a rare case were this happens. One evidence that this are not common is the epidemiological data of African countries, if this kind of transmission occurs the epidemic data will be far more worst.
that would really depend on the rate of transmission.

Quote Quote by nismaratwork View Post
This is very clear, from the epidemiology alone, and from basic biology. To ask this shows a fundamental lack of understanding as to how insect-borne disease DOES find a transmissible intermediary.


http://www.sfaf.org/aids101/transmission.html

Here is some research that will allow you to understand which insects make proper vectors for disease, and further research can explain why: http://www.cals.ncsu.edu/course/ent4...anvectors.html

I doubt you could find a single case of mosquito-borne HIV that you could possibly confirm, however close you look. HIV requires more than a single virion to cause infection.
that's the trouble with epidemiology. if it's a rare event, you probably won't see the outliers, or if you do, you'll just reject them as outliers.
nismaratwork
#11
Jun13-10, 12:45 PM
P: 2,284
Quote Quote by Proton Soup View Post
that would really depend on the rate of transmission.



that's the trouble with epidemiology. if it's a rare event, you probably won't see the outliers, or if you do, you'll just reject them as outliers.
In the context of what is a massive worldwide pandemic, yes that can happen. The nature of HIV infection, and the feeding habits of mosquito added to the epidemiology makes it pretty much impossible however. I hear a lot about the use of needles in IV drug use, but in that case blood is drawn into the chamber of the syringe first, not just a light coating on the needles. Remember also, that sharing needles tends to be a repeated event, allowing for infection, not just a miraculous mosquito. A mosquito's saliva is going to rapidly digest HIV (just protein to the bug) and the feeding apparatus is retracting and cleaned with saliva.

Maybe if a mosquito fed on someone with full-blown AIDS and a massive viral count, then flew directly into an open wound on another body seconds after feeding you COULD be infected... even then I wouldn't bet on it.
AlexB2010
#12
Jun13-10, 12:49 PM
P: 39
Quote Quote by Proton Soup View Post
that would really depend on the rate of transmission.



that's the trouble with epidemiology. if it's a rare event, you probably won't see the outliers, or if you do, you'll just reject them as outliers.
Biology is still so much diverse, the fact that you find a single case doesn’t means this happens in a significant number of cases.
Impossible? No. Improbable? Yes. Neglect able? Yes.
Proton Soup
#13
Jun13-10, 12:53 PM
P: 1,070
i'm sure it's an extremely low probability. but it would still make me think twice in certain social situations, as i am a mosquito magnet.
AlexB2010
#14
Jun13-10, 12:57 PM
P: 39
Quote Quote by Proton Soup View Post
i'm sure it's an extremely low probability. but it would still make me think twice in certain social situations, as i am a mosquito magnet.
Buy some lottery tickets… you will have better chances.
nismaratwork
#15
Jun13-10, 01:09 PM
P: 2,284
Quote Quote by Proton Soup View Post
i'm sure it's an extremely low probability. but it would still make me think twice in certain social situations, as i am a mosquito magnet.
Obviously there is no study that is going to say, "this is impossible", but Proton Soup: it's basically impossible. It just is not that easy to be infected with HIV! You are essentially talking about a near-microscopic needle stick, but one that has been cleansed with enzyme-rich saliva.

Maybe we need to look away from the bugs, and to the rate of transmission from REAL needle-sticks:

Quote Quote by CCohs Canada
What are the hazards of needlestick injuries?

Accidental punctures by contaminated needles can inject hazardous fluids into the body through the skin. There is potential for injection of hazardous drugs, but injection of infectious fluids, especially blood, is by far the greatest concern. Even small amounts of infectious fluid can spread certain diseases effectively.

Accidental injection of blood-borne viruses is the major hazard of needlestick injuries, especially the viruses that cause AIDS(the HIV virus), hepatitis B, and hepatitis C.

The risk of infection after exposure to infected blood varies by bloodborne pathogen. The risk of transmission after exposure to HIV-infected blood is about 0.3%, whereas it is estimated to be up to 100 times greater for hepatitis B virus (30%) and could be as high as 10% for hepatitis C virus.
http://www.ccohs.ca/oshanswers/disea..._injuries.html
http://www.avert.org/needlestick.htm

Note the risk factors:

Quote Quote by Avert
Certain specific factors may mean a percutaneous injury carries a higher risk, for example:

A deep injury
Late-stage HIV disease in the source patient
Visible blood on the device that caused the injury
Injury with a needle that had been placed in a source patient's artery or vein
So, if you're in Africa working in palliative care for people dying of AIDS with massive viral counts, you need a mosquito with a trocar for a proboscis, and glistening red as it fails to clean itself and them plunges into you. You will die of malaria, or dengue, or old age and paper cuts from Alex's lottery tickets before you contract HIV from a mosquito.


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