Is it true that mosquitoes prefer biting people of one blood type over another?
The quick answer to your question is, yes, studies have shown that people with blood type O are more likely to be bitten by a variety of mosquitoes. In the first major paper on this subject, Wood and colleagues found that after re-creating field conditions and directly testing the blood meal of each mosquito, type O was the most popular (2). A more recent study, which counted the number of mosquito landings on each human forearm, found similar results. Furthermore, these data suggested that type O secretors, those who release blood antigens in their saliva and mucus, are bitten much more often than type A nonsecretors (3).
However, type O might not necessarily be a bad thing if you are around lots of mosquitoes. Researchers have hypothesized that during Plasmodium falciparum infection, the major malaria parasite, those with type O blood are more likely to survive whereas those with type A are more likely to experience severe malaria (4). This finding is consistent with the observation that higher ratios of blood type O to A are seen in malaria-endemic areas compared with colder areas where mosquitoes cannot survive. Moreover, the selection pressure that favored emergence of type O alleles from type A occurred around the same time that P. falciparum emerged, suggesting that blood type O and the mosquito-transmitted parasite are linked in evolutionary history (5). Why type O people seem to be protected from severe malaria is unclear. It may be because protein molecules on the surface of P. falciparum erythrocytes cannot bind to antigens on blood cells of other blood types. This lack of ability to bind prevents the clumping of red blood cells and subsequent sequestration of infected cells to blood vessel endothelium. Because there is less obstruction of blood vessels, the lowering of blood supply to critical organs such as the brain, common in malaria, is prevented. (4).
Despite this information, most studies suggest that fluctuating carbon dioxide (CO2) levels and human odorants are the essential sensory clues for mosquitoes, not blood type. Mosquitoes use CO2 receptor molecules on their antennae to find you, and certain human odorants can inhibit or enhance this pathway. In an interesting paper, Ray and colleagues showed that although some odorants such as butanal directly inhibit the CO2 detection pathway, others such as 2-butanone imitate CO2 to lure mosquitoes into traps. Other chemicals such as 2,3-butanedione act as “blinders,” causing extended activation of CO2 detection pathway neurons and disabling their machinery like a circuit explosion (6).
So, if you want to avoid mosquitoes, here are some tips: Change your blood type, stop breathing, do not get pregnant (7), and do not drink beer (8).
1. Hill, C.A., Kafatos, F.C., Stansfield, S.K., and Collins, F.H. 2005. Arthropod-borne diseases: vector control in the genomics era. Nat Rev Micro 3:262–268.
2. Wood, C.S., Harrison, G.A., Dore, C., and Weiner, J.S. 1972. Selective feeding of Anopheles gambiae according to ABO blood group status. Nature 239:165.
3. Shirai Y., Funada, H., Seki, T., Morohashi, M., and Kamimura, K. 2004. Landing preference of Aedes albopictus on human skin among ABO blood groups, secretors or nonsecretors, and ABH antigens. J Med Entomol 41:796–799.
4. Rowe, J.A., et al. 2007. Blood group O protects against severe Plasmodium falciparum malaria through the mechanism of reduced resetting. Proc Nat Acad Sci 104:17471–17476.
5. Cserti, C.M., and Dzik W.H. 2007. The ABO blood group system and Plasmodium falciparum malaria. Blood 110:2250–2258.
6. Turner, S.L., Li, N., Guda, T., Githure, J., Carde, R.T., and Ray, A. 2011. Ultra-prolonged activation of CO2-sensing neurons disorients mosquitoes. Nature 474:87–91.
7. Lindsay, S., Ansell, J., Selman, C., Cox, V., Hamilton, K., and Walraven, G. 2000. Effect of pregnancy on exposure to malaria mosquitoes. Lancet 355:1972.
8. Levere, T., Gouagna, L.C., Dabire, K.R., Elguero, E., Fontenille, D., Renaud, F., Costantini, C., and Thomas, F. 2010. Beer consumption increases human attractiveness to malaria mosquitoes. PLoS One 5:e9546.