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Insect Bite Prevention For Travelers
The number of mosquitoes in the world is exceeded only by the number
of insect repellant products for sale. 

DEET
DEET & Sunscreen
Fogging Spraying & Coils
Mosquito Netting
Permethrin
Picaridin
Plant-based Repellants
Vitamin B, Wrist Bands & Other
Updated Info On Mosquito Repellants -CDC Link

DEET
DEET is an abbreviation for the chemical name, N,N-diethyl-3-methylbenzamide.  It has been used in the US since the 1950's.  Most insect repellants contain DEET as their active ingredient.  DEET effectively repels mosquitoes, biting flies, chiggers, fleas and ticks.  Check the concentration of  the product you buy, as some are very weak and require more frequent application. 

The strongest of the common drugstore brands is about 25% DEET, which is satisfactory in many cases.  Ultrathon, a 3M product, comes as a 30-33% lotion and may be found locally.  Experts usually do not recommend over 35% strength.  There may be no significant advantage to controlled release DEET products.  DEET in the 95% strength is commonly found but recommended only in unusual settings. 

High concentration DEET can dissolve watch crystals, plastic eyeglass frames and lenses, and certain synthetic fabrics.  The effectiveness of DEET is diminished by perspiration, rain, swimming and rising outdoor temperatures. 

Infants & Children:
There is no toxicity reported when DEET is used properly, however seizures were reported in a small number of infants and children years ago due to over usage.  The American Academy of Pediatrics has loosened up their warnings about DEET considerably, and recommend percentages up to 30% for infants over 6 months old.  It would be better to not use the maximum allowable frequency of dosing in infants.  Do not use under 2 months of age.

DEET is not more effective above concentrations of 30%.   However, as the concentration of DEET increases, the duration of activity increases.  For example, concentrations of 10% are effective for about two hours and concentrations of 24% are effective for about 5 hours.
www.aap.org/family/wnv-jun03.htm

Other pediatric precautions:

  • Apply DEET sparingly on exposed skin; not under clothing.
  • Do not apply near eyes, mouth and on sucking fingers.
  • Do not apply over cuts, wounds or irritated skin.
  • Avoid spraying in enclosed areas or near food.
  • Wash skin and clothes with soap and water afterward.
     

DEET & Sunscreen
Combination products are not generally recommended.  DEET decreases the efficacy of sunscreens by 34%.  Sunscreen should be used liberally and often, whereas DEET should be used sparingly as required.  However, if application of both is required, the Canadian Dermatology Association recommends that the sunscreen be applied first and allowed to penetrate the skin for 20 minutes prior to applying DEET.

Picaridin
Prevention of bites from mosquitoes, ticks, and flies is an important way of preventing disease. Most travel experts recommend only DEET or picaridin based repellants.  In the insect repellant industry, picaridin is known as KBR3023.

Picaridin is now available in the US in these strengths:

  • "Off!® FamilyCare INSECT REPELLENT II Clean Feel"-5%

  • "Cutter® Advanced"-7%

  • "Cutter® Advanced Outdoorsman" or "Sport"-15%
    (Look for these exact three words on this product, and 15 % picaridin in sporting stores and Wal-Mart sporting department)

Low concentrations of either picaridin or DEET are much less or minimally effective, depending on the biting habits of the attacking mosquito.  DEET of 30% to 35% concentration and picaridin of 15% should be used in significant mosquito areas.   

The 19.2% strength picaridin is available in Europe and elsewhere and reported equal to 35% DEET.  Picaridin is called icaridin in other countries and can be purchased under the names Bayrepel®, Hepidanin® and Autan Repel®.  Research indicates it is safe. 
www.medletter.com/freedocs/picaridin.pdf

Plant-based Repellants
Oils from citronella (Skin-So-Soft® Bath Oil), cedar, eucalyptus, peppermint, lemongrass, geranium, and soybean plants have been used as repellants.  All of these have short-lived repellant activity (usually less than 30 minutes), except oil-of-eucalyptus which has activity similar to very low DEET concentrations.  These products will give minimal or poor mosquito repellant protection
(N Eng J Med, Vol. 347,13-18, July 4, 2002)

Mosquito Netting
Besides antimalarial medications, mosquito netting is one of the most efficient ways of protecting yourself from malaria.  Night time is when malarious mosquitoes are most active and you are most vulnerable.  A few always find their way into a house even though screened.

In malarious areas, mosquito netting should always be used if sleeping quarters are not well screened.  Many locals will use netting even if the house is screened.  Consider bringing a roll of netting on your trip.  Stringing up netting can be challenging.  Bring a small roll of clothes line cord to string it up and a small roll of duct tape to fasten the cord to the ceiling.  Check with sporting goods stores or www.longroad.com for nets that have their own support and do not need to be strung up.

Air conditioned apartments and homes that remain closed up generally will not have in-door mosquito problems. 

Permethrin
If you are going to areas of high mosquito and tick exposure, consider treating some or all of your outer clothes and mosquito netting with permethrin before your trip.  This will prevent mosquitoes from biting through clothes and minimize tick bites. Treated mosquito netting has been shown to be much more effective than non-treated netting.  Permethrin has been rarely reported to exacerbate asthma or cause local irritation.

Most spray cans of permethrin only treat one set of clothes, which are protective against mosquitoes for one week or one washing. One bottle of 0.5% permethrin solution, when diluted as directed, treats one set of clothes (shirt, slacks, socks) and is protective for 6 weeks or 6 washings.  An easy description of how to treat clothes with permethrin liquid is provided with the product.

Cabela's is the only place I have seen permethrin solution  for sale in SD.  It is sold as Sawyer Duranon Permethrin Insect Repellent® at $6 per bottle. Online at www.cabelas.com under camping essentials.

Pretreated clothes which are protective against mosquitoes for 50 washings or one year can be bought online at www.buzzoff.com.

The following information on permethrin treatment of fabrics is provided by Coulston, a maker of permethrin.  I have not seen these concentrations available in stores.

  • Use 0.125 mg. permethrin per square cm of fabric (accomplished by use of 16 oz. of 0.8% permethrin solution applied by soaking or wicking) which lasts one year, through 50 detergent washings or the life of the garment, whichever comes first.

  • Use of 0.026 mg. permethrin per square cm (2.5 oz. of 1/2% permethrin to garment by spray) lasts 6 weeks or 6 launderings.

  • Use of .008 mg. per square cm. (1.5 oz. of 1/2% permethrin by spray) lasts 2 weeks or 2 launderings.

After treating clothes with permethrin you still must use DEET or picaridin on exposed skin.

Fogging Spraying & Coils
Fogging your room or tent in the evening will be helpful for those mosquitoes that invariably sneak in when doors are left open or screening is poor.  Many spray insecticides are designed for this. 

After a light fogging, stay out of the room or tent for one half hour. Spraying walls and curtains lightly with an indoor insecticide will have added benefit.

Insect repellant and killing coils can be burned before retiring or during the night.  They come in many different types.  Opening windows for ventilation will decrease their effectiveness.  Some experts question their effectiveness whether windows are open or not.

In general, natural pyrethrum or synthetic pyrethroid coils are thought to be safe.  Burning coils may have a local irritating effect.  One must question the wisdom of leaving anything burning while sleeping.

Vitamin B, Wrist Bands & Other
Neither high dose Vitamin B (thiamine) nor garlic ingestion have been shown to have insect repellant properties.  Wrist bands impregnated with citronella or DEET do not work because these repellants are not effective more than a few inches from the site of application.  Personal sound emitting devices worn to repel insects have not been shown to be effective.
 

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