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Forum Name: Pharmacy & Drug Topics

Question: Waterproof DEET

 mrtubs - Thu Nov 12, 2009 12:05 pm

I am soon to travel to the Dominican Republic from the UK. I have been advised to take anti malaria tablets which I have, but also to use an insect repellant containing 50% DEET as there has been an outbreak of somesort of fever (sorry I cannot remember the name).
Is it possible to buy a waterproof version as I have not been able to find any in the shops. I don't really fancy spraying everytime I go into the water.
 Dr.M.Aroon kamath - Wed Jul 14, 2010 8:39 am

User avatar Hi,
I believe you are referring to the "West nile virus" which first occured in 1937 in the West Nile district of Uganda.The first epidemic in the western hemisphere started in north america in 1999.West Nile virus (WNV) activity in the Dominican Republic was reported for the first time in november, 2002.

Affects many bird species, horses and humans.Transmitted by mosquito bites. Migratory birds were the prime suspects for the rapid spread of WNV through North America.

Mosquitoes are attracted to humans by skin odors and carbon dioxide from expired air. The active ingredients in repellents make the person unattractive for feeding.

DEET (N,N-diethyl-m-toluamide) and
Picaridin (KBR 3023) are two of the most reliable and tested mosquito repellents.

Perspiration or getting wet may result in the need for re-application. In general one should re-apply repellent if one starts to get bitten by mosquitoes again.
Many of the mosquitoes that carry this virus bite between dusk and dawn. Repellents containing a higher concentrations (higher percentage) of active ingredient tend to provide longer-lasting protection.

A product containing 23.8% DEET provided an average of 5 hours of protection from mosquito bites.
A product containing 20% DEET provided almost 4 hours of protection
A product with 6.65% DEET provided almost 2 hours of protection
Products with 4.75% DEET were both able to provide roughly 1 and a half hour of protection.
(Fradin and Day, 2002, CDC publications)

DEET concentrations higher than 50% do not increase the length of protection.

Some of the recommendations for avoiding mosquito bites effectively are,
- one should choose a repellent that provides protection for the amount of time that one will be outdoors.
- one should choose a product with a higher percentage of active ingredient if one will be outdoors for several hours while a product with a lower concentration can be used if time outdoors will be limited.
- repellent should be re-applied if one expects to be outdoors for a longer time than expected.

I am not aware of any water-proof mosquito repellent containing the aforesaid safe,tested and peer reviewed chemicals.
Best wishes!

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