INSIDE

Health Matters

By Virginia Lester,
RN, MSN, ARNP

This article is in response to questions regarding safety in the use of products that contain DEET to protect against insect-borne diseases. Children are at a greater risk but adults are also susceptible to such diseases.

Insect bites in the United States most commonly cause a local inflammatory reaction that subsides within a few hours and is no more than a nuisance. Worldwide, mosquitoes transmit infectious disease to more than 700 million people; one out of 17 deaths are due to a mosquito bite transmitted disease such as malaria, yellow fever, dengue, and encephalitis. Tick borne illness is also common.

On the other hand, systemic reactions to insect bites are extremely rare compared with insect stings. The most common insects associated with systemic allergic reactions were the Triatoma (kissing bugs), followed by blackflies, deerflies, and horseflies. 

The most commonly occurring insect bites are inflicted by mosquitoes. Only females bite, since they require a blood meal to produce eggs. Mosquitoes are often found around standing water since they need an aquatic environment to complete their life cycle. Transmission of infectious and potentially lethal diseases has been seen after mosquito bites.

West Nile fever emerged in 1999 when animals and humans died after being bitten by mosquitoes infected with the West Nile virus. However, mosquitoes do not transmit HIV infection since the virus neither survives nor replicates well in mosquitoes, and blood from one meal is not flushed into the next host.

Mosquitoes may be attracted to humans by a number of factors:
•Host movement and dark clothing may attract mosquitoes that feed during the daytime.
•Carbon dioxide released from the breath and skin serves as a long range attractant.
•Mosquitoes have chemoreceptors on their antennae that are stimulated by lactic acid.
•Predilection for different human body parts may reflect local skin temperature and sweat gland output; individuals who do not sweat are less commonly bitten by mosquitoes.
•Host odors as well as perfumes, soaps, lotions, and hair care products are powerful attractants.
•Adult men are more frequently bitten than women and children.
Three steps to prevent bites: Avoid, cover up and repel. Mosquitoes are most active at dawn and dusk, so staying indoors during these times is best. Covering up with long sleeves, pants and socks protects from bites. Repellents provide highly efficient protection against insect bites.
DEET is an effective product for protection against mosquitoes, biting flies, chiggers, fleas, and ticks. No other compounds cover such a broad spectrum and offer the same extended duration of effectiveness. Extended release formulations (e.g., HourGuard) have made it possible to decrease the concentration of DEET without sacrificing its duration of action. DEET appears to be extremely safe, although adverse neurologic effects, although very rare, have been reported with massive exposure and chronic use.
Products with 10 to 35 percent DEET are adequate in most circumstances. Higher concentrations should be reserved for situations in which insect infestation is high and high temperatures and humidity may limit repellent efficacy. DEET should not be used in children under two months of age.
The environmental protection agency has issued guidelines regarding proper repellent application:
•Use just enough repellent to lightly cover but not saturate the skin. 
•Repellents should be applied to exposed skin, clothing, or both, but not under clothing.
•A thin layer can be applied to the face by dispensing repellent into the palms, rubbing hands together, and then applying to the face.
•Repellent should be removed from the palms after application to prevent contact with the eyes, mouth, and genitals.
•Do not use repellents over cuts, wounds, inflamed, irritated, or eczematous skin.
•Do not inhale aerosols or get them into the eyes. (Lotions are recommended for children.)
• Frequent reapplication of repellent is unnecessary.The areas treated with repellent should be washed with soap and water once the repellent is no longer needed.

Have a pleasant, insect-bite free summer.