Mosquito Magnet

-Sunita Gurung

The advent of summer brings in the warm weather giving us the much needed respite from the bitter cold. Unfortunately, along with the comforts, the season also brings in the swarming hordes of summer pests that can annoy the living daylights out of anyone. Besides the common houseflies that have their own unsanitary ways of brushing off the microorganisms on unsuspecting territories, the mosquitoes are armed with enough panache to disturb the mental equilibrium of your status even if it is momentarily. Enjoying a cool evening out after dinner always ends up getting stalked by this intruder which ultimately gets ruined by these noxious pests landing on you. While you become a luscious feast for the darned pests and go on a slapping spree you can’t help but notice that the people sitting around you seem unfazed. The inevitable question pops up, “Why am I the only one to get victimized?” The truth is that, mosquitoes do exhibit blood sucking preferences. One in ten people are highly attractive to mosquitoes say experts. But apparently, it seems that it is not dinner that they are seeking.
Dipak Sagar, Program Manager, Malaria, Population Services International/Nepal, elucidates, “Female mosquitoes – the males do not bite people (they feed on flower nectar and juices) – bite to obtain necessary proteins from blood so that they can produce eggs. Proteins in human and animal blood are necessary for the female mosquitoes to produce fertile eggs. Females require a new blood “meal” for every nest they lay.” Since human blood is a necessity for the female species, their blood sucking preference makes them attracted only to some people whose blood will suffice. With their well constructed proboscis, they pierce the skin, sucking the blood out. Before drawing out the blood, it injects a small amount of saliva which lubricates the opening while the chemicals in it prevent the blood from clotting. It is these chemicals that cause the stinging sensation and irritation that is well associated with a mosquito bite. In most cases, the itching sensation and the swelling disappears after a couple of hours, but in sensitive cases, it may persist for several days. Scratching can result in infection if bacteria from finger nails are introduced to the wound.

Who do the Mosquitoes Prefer?
“Some people are bitten by mosquitoes more often than others. While scientists have yet to pinpoint the exact reason why mosquitoes bite specific people, there are some well-known factors that play a role: giving off large amounts of carbon dioxide; wearing deodorant, perfume, cologne, or lotion; being outside at dusk; and wearing dark colored clothing. Overall, mosquitoes are attracted by smells. People with high concentrations of steroids or cholesterol on their skin surface attract more mosquitoes. That doesn’t necessarily mean that mosquitoes prey on people with higher overall levels of cholesterol. These people simply may be more efficient at processing cholesterol, the byproducts of which remain on the skin’s surface to attract more mosquitoes. Mosquitoes also target people who produce excess amounts of certain acids, such as uric acid. They are also attracted by people who emit large quantities of carbon dioxide. Pregnant women are also at increased risk, as they produce a greater-than-normal amount of exhaled carbon dioxide. Movement and heat also attract mosquitoes,” says Dipak.
As Dipak says, the researchers haven’t yet been able to discover what attracts or repels a mosquito. Research is being conducted on what compounds and odors people exude that might attract these bugs but with 300-400 different chemical odors to examine, the task is extremely daunting. These insects seem to have a keen power of smell that directs them to an ideal human flesh to feed on its blood. During the hunt, these pests do an aerial search of a possible target and, after they locate it, zero in. It seems that they are armed with sensors designed to track their prey that is why they are so good at finding and biting. Mosquitoes are insects that have been around for more than 30 million years and within this period they have been honing their skills and have mastered the technique of finding the most likely target.
Mosquitoes can carry diseases that can be transferred to humans through their bites, some of which are malaria, dengue fever, yellow fever, Chikungunya fever, Japanese encephalitis virus, et cetera.

Mosquito’s hot spots
Your body chemistry might guarantee that no mosquitoes will bother you, but where you are situated might be a haven for these pesky insects. In Nepal, malaria cases are being reported from 65 of the 75 districts. Approximately 22.8 million people (83 % of Nepal’s population) live in these malaria-endemic districts. The high-risk areas are the foothills and river belts, forest fringes, forests of Terai, valleys and inner Terai districts.
It is a well known fact that mosquitoes prefer stagnant water but any water source is a potential breeding ground. Dipak has this to say, “Many people associate mosquitoes strictly with standing water, with the belief that mosquito must have water to lay their eggs. Breeding habits of mosquitoes depend upon their species. Mosquitoes breed in stagnant waters (roadside ditches or containers), stream and seepage, slow-flowing waters with marginal vegetation, partially shaded slow flowing waters with marginal vegetations, and so on.”