DEET Still Tops For Mozzie Hammering

Some interesting stuff courtesy of OUTDOORSmagic member Ben Brockway who took time out from the ghastly horrors of New Zealand to put together this article:

Hot news from the New England Journal of Medicine - generally regarded as one of the best medical journals in the world. According to a large study into the effectiveness of a variety of insect repellants, DEET based repellents are still by far the best. The study also included Avon's 'Skin So Soft', an old favourite of fragrant hillwalkers everywhere.

Those crazy kids from the Florida Medical Entomology laboratory tested various concentrations of DEET, IR3535, Skin So Soft , citronella and impregnated wristbands. Foolhardy volunteers put their arms in cages of hungry mosquitos (fortunately proven to be clean living, disease free mozzies rather than malarial ones...).

Stunt Forearm...

Just to make sure the mozzies were awake an untreated stunt forearm was also put in the cage - presumably still attached to volunteer- until bitten five times, then the test forearms were inserted. And the study showed that DEET still rules the roost. 5% DEET gave protection for about 88 minutes while 24% gave protection for a whopping 300 minutes.

The best non-DEET product, based on soya-bean oil, managed to keep up with the feeblest DEET formula, but after that there was little hope for the volunteers. Citonella and Skin-So-Soft lasted for 10-20 minutes at best, and the impregnated wristbands gave a heady 12 to 18 seconds protection only!

So what does it all mean? Well, bear in mind this was a study involving Aedes Aegypti, a mosquito that carries malaria, the West Nile virus, and assorted viral encepahlitides that can cause havoc on the brain in the US. It didn't involve those particularly annoying midges that congregate out the back of the Kingshouse and other closer-to-home areas. So we still don't know if Skin-So-Soft works in Scotland, other than to make you smell better after a long day on the hill.

DEET Rules Okay

But for travel in malarial areas, high concentration DEET is the way forward - along with mozzie nets and hats if you can face them. Other research has shown the amount of extra protection from DEET concentrations above 40-50% is minimal, and garlic eating doesn't help repel mozzies, only other humans. Ultrasonic mozzie scarers are totally ineffective. The study also looked at newer eucalyptus oil based repellants and these had encouraging results, but still not up to the level of DEET.

And how safe is DEET? Well, it's not great stuff - it melts holes in map cases, watches and spectacles, so what effect does it have on your skin? The authors point out that it's been in use for 40 years - estimating 8 billion human applications - with about 50 recorded cases of toxicity; 75% of these resolving completely. So a 12 in 8 billion recorded incidence of adverse effects doesn't seem too bad, and these cases all involved long term, whole body usage of high concentration DEET.

Of course the best way to avoid catching malaria is still to go on holiday to Scunthorpe, but where's the fun in that?