Austin is a wonderful place to live, but because it stays warm here eight months out of the year, mosquitoes are a large part of Texas living. While enjoying time in the backyard, do you find yourself swatting these pesky critters while others are unaffected? Is it possible that some people are ‘mosquito magnets’ and attract more bugs than others? The answer is yes, and today’s blog will review the latest information on mosquito attraction and discuss why and how mosquito bites should be avoided.
Statistics suggest that one in ten people are highly attractive to mosquitoes. Researchers have identified up to 400 compounds and odors that humans exude that may account for this. Genetics certainly plays a role and may account for up to 85% of susceptibility to mosquito bites, affecting things such as cholesterol and steroid content of our skin that may cause mosquitoes to swarm. Mosquitoes also target people who produce excess amounts of certain acids, such as uric acid and lactic acid. These substances can trigger mosquitoes' sense of smell, luring them to land on unsuspecting victims.
Carbon dioxide is another attractant to mosquitoes, and they can ‘smell’ it even at long distances. Scientists estimate mosquitoes can detect carbon dioxide from a human’s breath up to 50 yards away! Since larger humans breathe out more CO2, mosquitoes are more attracted to adults compared to children. And anything that increases carbon dioxide release will also attract more mosquitoes, which doesn’t bode well for runners or people who work or exercise outdoors. Heat and movement also attract mosquitoes.
So what can you do to decrease your attraction to mosquitoes? Experts recommend these tips: 1) Whenever possible, wear long sleeves, long pants, and socks when outdoors. 2) The hours from dusk to dawn are peak mosquito biting times for many species of mosquitoes-- consider avoiding outdoor activities during these times. 3) Install or Repair Screens; some mosquitoes like to come indoors, so keep them outside by having well-fitting screens on both windows and doors.
Mosquito repellent is also recommended when spending any amount of time outdoors. The majority of available mosquito repellents use DEET (N,N-diethyl-meta-toluamide); in repeated studies, it's been proven the most effective chemical repellent on the market. Repellents with 23.8% DEET (most formulas contain between 10% and 30%) protect wearers for about five hours. It has been in use for over 40 years and has a good safety record.
DEET is approved for use by pregnant and breastfeeding women and by children when in concentrations of 10% or less. Since mosquitoes bite through thin clothing, spraying clothes with DEET provides additional protection.
In 2005, the CDC began recommending alternatives to DEET for repelling mosquitoes.
Picaridin, fairly new to the U.S., has been used worldwide since 1998. Marketed as
Cutter Advanced, picaridin has proved to be as effective as DEET but is said to be more pleasant because it is odorless and contains a light, clean feel. Picaridin is safe for children older than 2 months. The chemical
IR3535, better known as Avon's Skin-So-Soft, also has been marketed as a mosquito repellent in the U.S. in recent years. To date, research shows it's much less effective than DEET.
Metofluthrin, a new chemical approved by the EPA in 2006, has become very popular recently. Sold as
DeckMate Mosquito Repellent, it’s available as a paper strip (you place it in outdoor areas like patios and decks) and as a wearable personal repellent product (it comes in a small container with a replaceable cartridge and NOT applied to the skin).
If you want to avoid chemical-based repellents altogether, a few promising alternatives do exist. Many oils -- citronella, cedar, peppermint, lemongrass, and geranium -- provide short-lived protection.
Oil of eucalyptus products seem to offer the longest protection. Endorsed by the CDC, oil of lemon eucalyptus is available under the
Repel brand name and offers protection similar to low concentrations of DEET. Lemon eucalyptus is safe for children older than 3 years. Another non-chemical repellent worn as a skin patch contains
thiamine (vitamin B1) and is sold under the name
Don’t Bite Me! This repellent is based on a study done in the 1960s that showed that thiamine produces a skin odor female mosquitoes don't like (remember, it’s the females that bite and need blood to develop fertile eggs). Since the original research, no additional studies have confirmed thiamine's effectiveness as a mosquito repellent when worn on the skin.
If you hate to spray or slather yourself with various products, or don’t want to use chemicals,
mosquito traps may be the answer. They work by emitting substances that biting mosquitoes find attractive -- such as carbon dioxide, heat, moisture, and other mosquito-friendly byproducts. They attract, then trap or kill female mosquitoes. When placed strategically near breeding spots, they can effectively control mosquito populations. Another new idea in mosquito protection is
insect -repellent apparel (clothing infused with the chemical insecticide permethrin). Marketed as a must-have for outdoor enthusiasts, the military has used this technique for several years.
How risky are mosquito bites? For some, a bite can mean much more than a few days of itching since bites can cause significant allergic reactions in susceptible individuals. Mosquito-transmitted illnesses are also possible. The West Nile virus made its first appearance in the U.S. in 1999. In Texas, the virus first appeared in mid-June of 2002 and was found in blue jays in the eastern portion of the state. Since then, positive tests/cases have been reported in mosquitoes, birds, horses, and humans. Most people infected with WNV are asymptomatic. A minority develop meningitis or encephalitis, which can be fatal. Symptoms include fever, weakness, headache, and altered mental status. Skin rash, lymphadenopathy, conjunctivitis, abdominal pain, cough, dyspnea, and diarrhea may also be present.
Malaria is the most common (and oft-forgotten) mosquito-transmitted disease worldwide.
Although malaria outbreaks in the U.S. are rare, about one million people worldwide die of malaria every year, most of whom are young children in sub-Saharan Africa. And though malaria can be treated, prevention by distribution of inexpensive mosquito nets and insect repellents, or by mosquito-control measures such as spraying insecticides inside houses can be very effective. Another mosquito-borne infectious disease is
dengue fever, an acute, painful febrile disease commonly found in the tropics. This disease can be fatal, and since there’s no vaccine, treatment is usually supportive. Mosquito-control measures are important and help control transmission. I
n 2009 and 2010, outbreaks of dengue fever were reported in the U.S.
Besides netting and repellents, areas at risk for mosquito-borne illness should eliminate standing water near living areas and decrease the number of places where mosquitoes can breed. It is also helpful to get rid of items that hold water, such as empty trash cans, old tires, or unused children's toys. Also, because the West Nile virus affects birds, at times severely, seeing a number of dead birds should be reported to authorities. For additional information regarding West Nile virus in Texas, see: http://bit.ly/9dbKSG
Mosquitoes have been around for 170 million years, and there are more than 175 known species in the U.S. These robust summertime pests clearly will be with us for a long time. But you can minimize their impact by taking a few precautions as outlined above. Not only can you decrease those pesky itchy bites, you might prevent allergic reactions as well as serious infectious diseases. If you suspect that mosquitoes “like” you too much, or that you’ve developed problems from mosquito bites, please feel free to contact our office.
J. Alex Martinez,M.D.
