Itching to get rid of insect bites

In Finland there is an aphorism; the mosquito is more dangerous than the tiger. You might have heard about dangerous viral infectious diseases carried by mosquitoes such as dengue, yellow feverchikungunya, zika and the West Nile virus but you assume you are safe from these diseases by living in the United States. Think again.

As an example, since 2014, travelers to sunny vacation destinations such as Mexico and the Caribbean have contracted chikungunya from the bite of Aedes aegypti or Aedes albopictusmosquitoes. The latter is also called the Asian “tiger” mosquito though they do not reside in Finland. Chikungunya, a miserable flu-like illness ensues several days after the insect bite and consists of a severe headache, rash, muscle aches and swelling of joints. While not life threatening, the resultant joint swelling and pain is nasty, debilitating and at times lasts for months. In fact, recent chikungunya infections are occurring in Florida as some local mosquitoes’ species are susceptible and now carry the virus and can transmit the disease.

In order to decrease your chances of contracting insect borne infections don’t plan on swatting away the mosquito the instant they bite. During an attack the mosquito sticks your skin with their spear/mouth part called a proboscis. This needle-like instrument contains six ultra-fine microscopic straw like channels which first injects an anticoagulant saliva to prevent blood clots to facilitate feeding. The saliva is also laden with disease causing viral passengers. This all occurs before the mosquito begins sucking your blood for their meal. Once the mosquito bites it is too late and the release of histamine from the bite dilates local blood vessels and increases the spread of the virus. In fact, some mosquito bites are painless, and you only realize that you have been attacked from the resultant itchy red bump your body creates as a reaction to the insect’s saliva. Here is some more bad news; a single mosquito sometimes carries more than one viral disease-causing motile infections with one bite!

How to protect yourself

Your best bet for preventing the diseases are insect repellents which are approved by the FDA (Food and Drug Administration). Repellents create an invisible noxious barrier approximately 2 inches from the skin discouraging contact and biting.

On the other hand, insecticides are regulated by the EPA (Environmental Protection Agency) and kill insects with a neurotoxin nerve poison. Many insecticides are only approved for outdoor use while some pyrethroid insecticides, those derived from chrysanthemum are also approved for indoor use. Some repellents additionally act as insecticides such as permethrin. Insect replants are available as sprays, lotions, creams, powders, grease sticks and cloth-impregnated laundry emulsions. Examples of synthetic chemical repellents include DEET, Picaradin and IR353. Plant derived oils and synthetic repellents are permethrin, oil of eucalyptus and oil of citronella.

One of the most commonly used repellents is DEET which is effective against mosquitoes and ticks. It is available in concentrations from 5-10%, however 10-35% usually provide adequate protection. Concentrations greater than 50% are extremely irritating to the skin. DEET will not damage cotton, wool or nylon clothing but can damage rayon, leather and spandex. It can also dissolve plastic and vinyl upholstery. DEET is approved for use in children greater than 2 months of age and the American Academy of Pediatrics recommends a 10-30% concentration (higher concentration does not provide better protection only longer lasting protection). As an example, a 10% DEET repellent will usually last 90 minutes while a 30% product will last 5-6 hours.

Be careful with DEET and spandex

Picaridin repellant is a synthetic compound formulated to resemble piperine which is naturally found in black pepper. It is not only effective against mosquitoes and ticks but also biting flies and chiggers. It is available as a 7% solution and 15-20% aerosol spray but not recommended for children under 2 years of age. The advantage to this repellant over DEET is a lack of chemical odor, a non greasy feel and lack of damage to clothing and plastics.

Botanical repellants such as oil of lemon eucalyptus are also effective against mosquitos, ticks, biting flies and gnats. It is available as a 30-40% pump but the efficacy is short lived, like lower concentrations of DEET that are 7-15%. They are also not recommended for use in children less than 3 years of age. PMD is also a repellant of great interest; derived from lemon eucalyptus extract, it is the only plant-based repellant advocated by the CDC in malaria prone areas (as it was clinically proven to prevent malaria), another mosquito carried illness. It also has the same duration of repellency as DEET.

Citronella obtained from lemongrass is one of the most widely used natural repellants though few studies have shown its efficacy. This should not be relied upon to prevent serious insect borne disease in endemic areas. Also, Neem oil derived from an Indian evergreen tree may provide some protection from nuisance biting mosquitoes, but it should not be relied upon as a reliable repellant.

If people are truly reluctant to use DEET or Picaridin, an alternative is Bite Blocker. It is a commercially prepared product containing glycerin, vanillin, oils of coconut, geranium and 2% soybean oil. Studies have shown that using this alternative has the similar repellent as DEET. The later though is your best choice for repellent. Finally, avoid using combination sunscreen and insect repellent products. Repellent should only be applied to the skin one time per day while sunscreens are recommended to be reapplied several times per day. This can lead to repellent toxicity particularly in small children.