As the recent 2021 summer time months introduced elevated mosquito exercise throughout a lot of the U.S., Snopes readers wished to know if the buzzing pests had been attracted to one sort of blood over one other. A deeper look by the scientific literature revealed that amongst different elements — like hormone ranges or scents — there may be proof to counsel that mosquitoes could also be extra attracted to folks with Kind O blood — or no less than these people had been extra seemingly to be bit.
To grasp why these people are extra seemingly to be pestered by the biting bugs, we should first perceive what a blood sort is.
What Are Blood Varieties?
An individual’s blood sort is inherited and decided by the presence or absence of drugs often known as antigens, which might set off an immune response if they’re international to the physique, in accordance to the Red Cross. The 4 main blood teams — A, B, AB and O —are decided by the presence or absence of two such antigens, A and B, which can be discovered on the floor of purple blood cells. However there may be additionally a protein often known as the Rh issue which is current (+) or absent (-) to make up the eight most typical blood varieties: A+, A-, B+, B-, O+, O-, AB+ and AB-.
Kind O optimistic is the most common with greater than one-third of People with this kind. Kind O adverse, however, is called the “universal” blood sort and is the most typical blood sort used for transfusions when a affected person’s blood sort is unknown. (To seek out out your blood sort, a pattern of your blood have to be sampled or taken by a medical skilled.)
What Does the Science Say?
The American Mosquito Management Affiliation notes that there are greater than 3,000 species of mosquitoes, and although host choice might fluctuate relying on area and species, a number of research have supported the declare that mosquitoes is perhaps extra attracted to these with Kind O blood over others.
One such species, Aedes aegypti, is the key vector of Dengue in Sri Lanka. In 2019, scientists on the College of Sri Jayewardenepura in Sri Lanka set out to determine how sure blood varieties might affect a mosquito’s means to rear offspring. Laboratory-reared feminine mosquitoes had been uncovered to all 4 blood teams without delay in separate feeders. After feeding, the DNA of blood in mosquitoes was extracted and recognized and the imply variety of eggs per particular person was decided. The researchers discovered that the best choice was noticed for the blood group O. Nonetheless, nobody blood sort was discovered to affect a mosquito’s egg manufacturing over one other, begging the query: Why would possibly mosquitoes favor one sort of blood over one other? (Extra on that later.)
A small-scale research conducted in 2004 additionally discovered that of 64 take a look at topics, these with blood Kind O had been considerably seemingly to have a mosquito land on them than on different blood teams A, B and AB.
A 2009 research printed in Virology Journal discovered that people with O+ blood sort had been extra inclined than different group varieties to get chikungunya, a virus unfold to folks by the chew of an contaminated mosquito. The findings prompt that some folks might have a genetic predisposition to the illness or maybe are extra seemingly to be bitten and contaminated by virus-carrying mosquitoes.
In 1974, researchers at Oxford College found that when physiological variables had been accounted for, mosquitoes most well-liked the blood from hosts of blood group O. However a research performed in 2014 and printed within the peer-reviewed journal Acta Tropica discovered that mosquitoes had been extra seemingly to feed on both synthetic membrane blood feeders — or straight on human arms — of these with AB sort (40%) compared to different teams of A (24%), B (21%), and O (15%). Whereas the latter research doesn’t show that mosquitoes are extra inclined to chew Kind O people, the findings additional add proof that parasites like mosquitoes might favor sure genetic elements like blood.
Curiously, in each of the above research, people with AB blood varieties had been proven to have extra extreme instances of malaria than these of different blood varieties — a discovering that researchers counsel point out mosquito choice might function a type of pure choice for inhabitants management.
Why Do We Need to Examine Mosquito Choice?
Understanding how and why mosquitoes select a host isn’t just a matter of comfortability. In a lot of the world, it may be a matter of life or loss of life. The Facilities for Illness Management and Prevention (CDC) calls the mosquito the “world’s deadliest animal” and credit the long-legged insect with spreading ailments like malaria, dengue, West Nile, yellow fever, Zika, chikungunya, and lymphatic filariasis. The transmission of ailments by mosquitoes kills extra folks than another critter on this planet. In 2017 alone, an estimated 435,000 folks all over the world died from malaria alone and tens of millions extra turned in poor health with the illness.
Figuring out what blood varieties a mosquito is perhaps attracted to will help well being specialists and people take the required precautions to keep away from being bit by one (extra on that later). Moreover, understanding what people could also be extra seemingly to expertise illness severity will help within the remedy of an infection.
Different Components to Think about
However blood sort isn’t the one issue that will affect a mosquito’s alternative in a host. Virginia Tech researchers wrote within the journal Current Biology that mosquitoes have the flexibility to study which people would be the most advantageous for feeding.
“How mosquitoes determine which individuals to bite has important epidemiological consequences. This choice is not random; most mosquitoes specialize in one or a few vertebrate host species, and some individuals in a host population are preferred over others,” wrote the research authors in 2018.
These elements can embody pregnancy and hormonal fluctuations throughout numerous levels of a menstrual cycle, in addition to carbon dioxide, the compounds contained in sweat, alcohol intake, and even a preexisting malaria infection.
How to Shield Your self from Mosquito Bites
The CDC recommends sporting insect repellent, protecting up with lengthy clothes, and utilizing screens and followers on doorways and home windows to keep away from mosquitos.
“Mosquitoes bite during the day and night, live indoors and outdoors, and search for warm places as temperatures begin to drop. Some mosquitoes hibernate in enclosed spaces, like garages, sheds, and under (or inside) homes, to survive cold temperatures,” wrote the well being company.
For extra info on mosquito-caused ailments and the way to stop them, go to the CDC’s mosquito central.