Sometimes it is the tiniest of buggers that deal the largest of blows. This is none more true than for the wispy mosquito – we’ve tried to smash them, poison them, de-fertilize them, and yet, they still live to bite another day. They are the ultimate vectors of disease and destruction, killing more humans than humans themselves in 2013. Perhaps to deal with mosquitos then, we first have to look at ourselves and learn what makes us so vulnerable to their seed-sized bodies.

A new meta-analysis of blood type on susceptibility to severe malaria does just that, confirming the notion that those with O type blood are more protected from severe, fatal malaria than other blood types. Unfortunately, those of you with blood group A, B, and AB are less protected from severe P. falciparum infection.

“By better understanding how blood groups interact with malaria infections, we open doors for the development of treatment options and antimalarial vaccines," said Abraham Degarege Mengist, a doctoral student at the Robert Stempel College of Public Health & Social Work, in a statement.

The disease affects an estimated 219 million people in 87 countries, according to the World Health Organization. Of those, 435,000 died in 2017. All the more tragic, the disease is both preventable and curable.

The study suggests selection pressures may have increased the proportion of people with blood type O in sub-Saharan African countries where malaria is endemic. They suggest transfusions of blood group O to malaria-infected patients may therefore be preferable in regions where malaria is endemic.

Blood types are categorized by the presence or absence of antigens on the surface of red blood cells. You can be positive or negative depending on whether or not a protein called “Rh factor” is present. Around 47 percent of African-Americans are O-positive, while 39 percent of Asians are. O-negative is much rarer in the general population, with 4 percent and 1 percent of African-Americans and Asians respectively having this blood type, according to the Red Cross. These individuals are considered “universal donors” – their blood is most likely to mix well with another person’s and not result in complications. 

"Now that we are starting to understand the mechanisms of how blood type can affect the progression of the disease, we are exploring various options that can one day help people in the regions where malaria is endemic,” said Mengist, study author of the research published in the journal Blood Reviews.