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Why Do Mosquitoes Prefer People with Certain Blood Types More?

You might have noticed that some people seem almost immune to mosquitoes, whereas others are a prime target, always ending up with several bites after being outdoors for even a short period of time. 

Researchers have tried to determine why mosquitoes seem to prefer certain people over others. A prime focus has been on blood types, with some support that one blood type might be more attractive to mosquitoes than others. 

Which Blood Types Do Mosquitoes Prefer?

First of all, blood type is a genetic factor that is inherited from one’s parents. 

It initially appeared that mosquitoes have a preference for those with type O blood. In one study, they landed on people with said blood type much more often than they did people with type A blood type. 

This led to the conclusion that perhaps type O blood is simply more desirable to mosquitoes than type A. 

There’s More to The Story

Later research showed that while mosquitoes did seem to prefer people with type O blood, this was only when it was compared to type A blood. In other words, this preference disappeared when other blood types were thrown into the mix. 

So is it that mosquitoes really prefer type O blood, or do they only prefer it when the options are between type A and type O only? 


Some people are known as “secretors”. What this means is that they actually secrete the antigen of their blood type through body fluids, such as sweat. Mosquitoes are more attracted to people who are secretors than those who are not. 

Interestingly, when comparing blood type A and blood type O secretors, the mosquitoes preferred the O type more. 

What Does All This Mean?

The simplest conclusion is that we just do not know enough yet to be able to say with certainty what determines mosquitoes’ preferences. 

There is support that blood type might matter, but this appears to be limited to two types: O and A. Mosquitoes prefer O type over A type blood. However, they do not show this preference when other blood types, such as B, are added to the equation. 

Perhaps a more important factor is whether people are secretors or not. Mosquitoes prefer secretors over non-secretors regardless of blood type. 

Nevertheless, they still seem to prefer type O secretors over type A secretors. 

In other words, it does appear mosquitoes like type O blood better, at least when compared to type A blood. They also seem to prefer people who secrete their antigens through sweat and other bodily fluids. 

But you are not safe from mosquitoes if you have type A blood! There are many other factors influencing mosquitoes’ choices. 

Other Factors Involved

Mosquitoes seem to prefer individuals who emit more carbon dioxide. They appear to pick up on the greater concentration of carbon dioxide and move toward its source, which just might be you! 

Those who are pregnant also tend to give off more carbon dioxide, so if you are pregnant, beware! Mosquitoes might approach you more than normal. 

Female mosquitoes appear to seek out heat sources, so if you happen to be giving off more heat than others, they are likely to seek you out. 

If you are consuming alcohol, be prepared for an invasion, as mosquitoes tend to go for those who have been drinking. 


There are many factors influencing mosquito preference. Blood type is one of them, but there is much more to it than just that. 

They also seem attracted to heat, carbon dioxide levels, among other things. 

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