Published: July 16, 2008 11:05 am         

Pesky mosquitoes use crafty hunting skills to suck victims’ blood

Health Watch by Sherry Mullenix

The North Jefferson News



It’s summertime — the time for outdoor activities, backyard cookouts, etc.

Many families share these fun activities with friends and family members, but there is one uninvited guest. No, it’s not Uncle George, or Aunt Margaret, it’s those pesky mosquitoes. Growing up in the south, mosquitoes are a part of life if we go outside.

Mosquito facts

• Mosquito is Spanish for “little fly”

• There are over 140 different varieties of mosquitoes worldwide

• Only female mosquitoes bite

• Females must have a blood meal (biting a host) to breed

• Mosquito bites can transmit diseases like Malaria, Yellow Fever, Encephalitis, West Nile Virus and Dengue Fever

• Mosquitoes transmit diseases to more than 700 million people worldwide every year

• The average life span of a female mosquito can be up to 100 days, while a male lives for only 10 to 20 days

• Mosquitoes can only breed in still or stagnant water

• Depending on the species, females can lay 100 to 300 eggs at a time

• The egg matures in four to seven days

• Most mosquitoes never travel more than a mile from where they were hatched

Although small in size, mosquitoes have been around for over 30 million years. Remember the mosquito in the amber in the Jurassic Park movie? They have honed their hunting skills over those millions of years, and now use chemical, visual and heat sensors to locate their prey.

They can detect carbon dioxide and lactic acid at a distance of 100 feet. Certain chemicals in sweat also attract them. Who can cook those burgers and dogs without sweating? Not me!

Their visual hunting skills are somewhat less developed, but they can see you moving if you wear clothing that contrasts with the environment. You might think twice about wearing that bright yellow sun dress. They also use their heat sensors to detect warm-blooded mammals and birds in their vicinity. A human body is a very easy and large target for them to find.

With all these sensors and hunting abilities, it may make the mosquitoes sound more like a military aircraft than an insect. That is not far from the truth. That’s why they are so good at finding and biting you.

One of the only ways to stop mosquitoes from finding you is to confuse their chemical and other sensors. If the temperature allows, wear clothes that cover the body to mask body heat. Second, use a mosquito repellent that contains NN-dietheyl-meta-toluamide (DEET) at a concentration of no less than 7.5 percent.

DEET was first developed for use by the U.S. Army in 1946, and it became available to the public in 1957. Many other products have hit the market since then, but few compare to DEET. In fact, it’s one of two ingredients in mosquito repellent that the CDC recommends for preventing mosquito-borne diseases. The other is picaridin.

The CDC believes these two ingredients are more effective than other mosquito repellents. A concentration of around 15 percent is recommended for children.

Off! Deep Woods repellent, a product containing about 24 percent DEET, fared the best. Its protection lasted an average of five hours. It is recommended to spray clothes as well as skin, as mosquitoes can bite through some thin materials.

The least effective products were wristbands treated with DEET or citronella, which offered almost no protection. According to the researchers, this wasn’t a surprise. It’s known that mosquito repellent only works on the surface to which it’s directly applied. Mosquitoes are happy to bite skin only four centimeters away from the repellent area.

Let’s look at how the mosquito does its damage. As mentioned before, only the female mosquito bites. When the mosquito bites, it injects it’s saliva into the skin. It’s saliva contains chemicals (anticoagulants) that keep the blood from clotting.

She will then start sucking your blood into her abdomen, about 5 microliters per bite. If she is disturbed, she will fly away. If not, she will continue till her abdomen is full. After she is full and has gone about her merry way, some of the saliva remains in the wound. The proteins found in the saliva evoke an immune response from the body. The area swells, and a bump is formed around the bite. It starts to itch.

Eventually, the swelling goes away, but the itch will remain until the immune system breaks down the proteins found in the saliva. To treat a mosquito bite, wash the area with soap and water and try to avoid scratching. Scratching only spreads the proteins left behind by the bite.

This is also how the mosquitoes transmit diseases. When a mosquito bites an infected host, such as a bird infected with the West Nile Virus, that virus shows up in the saliva the mosquito leaves behind when it bites a person. One misconception is that HIV can be transmitted by mosquitoes. The HIV virus can not survive in a mosquito, therefore, it can not be transmitted by this method.

Prevention

Since mosquitoes need water to breed, eliminating any standing water in your backyard will prevent breeding. Mosquitoes can breed in as little as a few millimeters of water, so look for all sources of stagnant, standing water. If you have a tire swing, make sure it is dry. Empty any saucers or dishes under flower pots, etc.

With some precautions and a little prevention, maybe the burgers and hogs will be the only thing eaten at your next cookout.

Sherry Mullenix (J.D., R.N.) co-owns The Pharmacy in Mount Olive with her husband, Steve Mullenix (R.Ph). They can be reached at 631-1201.