SEE THE TYPE OF BLOOD GROUP MOSQUITOES PREFER TO BITE.
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the windows and ravage your ankles; they find
the one spot on your left shoulder that didn’t get
drenched in a layer of DEET (God bless you, Deep
Woods Off!) and gnaw, chomp, and suck away.
From May to September, many of us – covered in
scars and bloody scabs, the remnants of these
bites now gone bad – live side-by-side with
people who, despite living in the same house and
even sleeping in the same bed, are seemingly less
vulnerable to the vicious six-legged predators. It
turns out, a mosquito’s snacking preference for
one person over another is not just a curious
annoyance, it’s also a medical concern : Since
malaria and other diseases are transmitted by
bites, people who get bitten a lot are more likely
to become ill. Because of this, researchers are
working to find the mechanisms in mosquitoes
that cause them to sniff out you, and not your
neighbor.
Scientists have identified several proteins found
in mosquitoes’ antennae and heads that latch on
to chemical markers, or odorants, emitted from
our skin. These markers are produced by the
natural processes of our bodies and, like neon
signs, they let the mosquitoes’ smell center know
you’re around (though the process that then
guides them to you is not well understood). Flies
and mosquitoes share a number of the same
genes that dictate production of these odorant-
binding proteins, which have specific sites that
will catch or bind with certain chemicals in the
air. Some scientists suggest that certain
characteristics attract mosquitoes, thereby
leading us to have more bites than others. Some
of the top candidates: the amount of carbon
dioxide in the breath, pregnancy, body
temperature, alcohol and odorant markers based
on blood type.
Blood-type markers are chemicals released by
people of a specific blood type – so if someone
with AB blood emitted a marker, it would be
different than that released by B. One study
found persons with Type O blood suffered more
mosquito landings because of the odorant
markers they emit than any other blood type,
making their juices a hot commodity for blood
banks, as well as Asian Tiger Mosquitoes, which
carry West Nile Virus. Not only were Type O’s
more likely to be landed on, but the study found
that for any blood type, people who secreted a
chemical marker about their blood type through
their skin (both blood type and secretor status
are determined by genes) were bitten much more
than non-secretors; 24 percent in the case of the
Type O’s. Other researchers estimate about 15
percent of the population, based on their genes,
don’t emit chemical markers of their blood type
through their skin and saliva, so something else
has to be calling the mosquitoes to them.
Pregnancy seems to be a big winner for mosquito
attraction, probably because mothers-to-be
exhale 21 percent more carbon dioxide (quite a
turn-on to the six-legged species) and are on
average 1.26 degrees Fahrenheit warmer around
the belly than their non-pregnant counterparts,
due to the temperature of amniotic fluid. Also,
having just 12 ounces of beer increases your
mosquito appeal, possibly because of the increase
in body temperature it causes or because skin
markers change when metabolizing cocktails –
unfortunate since outdoor drinking is a highlight
of summer anywhere.
One researcher suggested smell is unimportant,
and what really matters to the mosquito
currently chomping on your toe is not the smells
you’re giving off, rather it’s finishing her meal
without being swatted away. Because of this,
she’s better off attacking “less defensive”
animals, rather than more defensive, and so is
evolutionarily predisposed to biting lazy or
incapacitated prey (reference drinking above).
Infectious disease experts are anxious to solve
the mosquito preference puzzle so they can
design repellants tailored to vulnerable people,
which would either block an individual’s smell
signatures or disarm a mosquito’s scent
receptors. Unfortunately, a specific answer to
your skin-piercing question continues to itch
away at scientists, and I suggest stocking up on
bug repellant in the meantime.
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