99mkw

I decided to search the medical literature for evidence on the efficacy of various insect repellents. Here is a sampling of the findings:

<b>Catnip:</b> Two 2005 articles from the Journal of Medical Entomology reported comparison of catnip to DEET. Both showed some effect in artificial tests, but only one actually looked at people getting bit. They wrote in the abstract: &quot;We conclude that catnip oil and nepetalactone isomers are significantly less effective than deet or SS220 in deterring the biting of Ae. aegypti.&quot;

<b>DEET %:</b> A 2005 practice recommendation which reviewed the literature reported that concentrations of DEET over 30% offer no increase in effectiveness, but they are effective for longer durations. The full text is located at www.jfponline.com/Pages.asp?AID=1931

<b>Citronella:</b> A 2003 paper looking at topical citronella found it prevented bites for only 2 to 20 minutes. For candles (and I assume burning oil), one study found they were slightly better than regular candles, which were slightly better than nothing at all. Another study from 2000 field tested various non-topical products against topical DEET in Illinois. They found DEET beat all of the non-topical products, but that mosquito coils and deet-impregnated wrist bands were better than control. Reading between the lines, the other non-topical items, including citronella candles, were no better than no treatment at all.

<b>Picaridin and PMD:</b> A nice review article of sunscreen and insect repellents in Current Opinion in Pediatrics (2004, pubmed ID 15273497) cited studies showing comparable effect between 19.2% picaridin and 35% DEET. PMD (p-methane-3, 8 diol), a derivative of eucalyptus oil, was mentioned as comparable to DEET at high concentrations based on a review of field tests in Ethiopia. A separate article from 2004 Journal of Medical Entomology (pubmed ID 15298309) compared four synthetic repellants to eight plant-derived ones. Repel, containing 26% PMD, lasted longer that Off w/ 15% DEET, which in turn lasted 50% longer than a repellent w/ 7% DEET. The only other natural product that lasted longer than 7% DEET was Bite Blocker (2% soybean oil), which lasted as long as the 15% DEET. Before you run out to get Bite Blocker, the same product was tested in a 2002 New England Journal of Medicine article and found much shorter duration of protection. As is so often the case with medical literature, contradictions abound!

If you are a real glutton for information, there was an excellent review in the Annals of Internal Medicine back in 1998 that cited 122 papers. Free full text access is available at www.annals.org/cgi/content/full/128/11/931

That article cited perhaps the ultimate mosquito prevention: &quot;In a field trial conducted in Alaska, persons wearing permethrin-treated uniforms and a polymer-based 35% DEET product had more than 99.9% protection (1 bite/h) over 8 hours, even under conditions of intense biting pressures; unprotected persons received an average of 1188 bites/h.&quot; Ex Officio's BUZZ-OFF contains permethrin plus a prorietary compound, so if you're really worried about bites you can invest in some of that clothing.

-Matt

Kavey

Thanks Matt!
So if I'm happy to reapply regularly, 30% DEET is fine, but 50% might be better if I'm not going to reapply as regularly because it will last longer?

africnow

Hi Matt,

This is very much appreciated indeed. Had someone from the USA offer to buy the DEET for me and ship it to me here in Israel.

So shall I ask her to get 35% DEET? I can pick up Eucucalyptus oil here, also lemon oil. Do they need to be mixed with anything special? The candles and insect repellent rings aren't worth the cost and trouble, if I understand correctly?

Thanks!

cybor

As an xnurse I agree with Matt in that medicine is a very inexact science and thus lot's of findings will change or be contradicted.
That said, most of the mosquito solutions are put into other compounds that will further dilute them of their % of DEET. Also, most of these products will break down after sitting in your closet for years/many mos. on end or by being exposed to temp. changes - so replace prior to your trip.
We brought 30% and wore the treated shirts when there were a few mossies buzzing around and didn't get bit once. As Sandi said, unless your around wet areas you won't see too many mossies. So take your maleria pills (unlike some folks , cover up and go enjoy your trip.
Sherry

99mkw

Kavey-

The thing I failed to mention about % DEET and duration of effect is that some lower % DEET products have extended release formulations. The 1998 article I linked discusses this in the section &quot;efficacy&quot; under the DEET heading of the Chemical Insect Repellent Section:

&quot;Extended-release formulations of DEET have made it possible to reduce the repellent concentration without sacrificing duration of action. When tested under laboratory and several different environmental and climatic field conditions, the 35% DEET polymer formulation by the 3M Corporation was as effective as 75% DEET in repelling mosquitoes [19, 47-50]. The polymer formulation provided up to 12 hours of more than 95% protection, depending on the environmental conditions and species of mosquito tested [46, 48, 49, 51].&quot;

I believe that the 3M formulation cited is basically the Ultrathon product mentioned above by jcasale and tigerpaw (although I think it has a 24% version in addition to the 33% version make sure you're getting the one you want).

Africnow-

I'm not sure whether or not it's worth having DEET products shipped to Israel. It probably depends on just how concerned you are and how much protection you feel is necessary.

Your original post mentioned Picaridin as a natural product, but my reading said it was a synthetic like DEET which is touted to have less skin irritation. <b>PMD</b> is derived from oil of lemon eucalyptus (Eucalyptus maculata citrodion), which I think is different from just eucalyptus.

I copied the wrong pubmed ID for that 2004 test of various agents. If you want to read the abstract, go to www.pubmed.com and enter 15311467 into the search field. They tested several mosquito species and the following products had average protection over 7 hours: Autan (10% KBR3023 = <b>picaridin</b>, Bite Blocker (2% soybean oil), Off! (15% DEET), and Repel (26% PMD).

Can you get a product w/ 20% picaridin? In the US all we have so far is Cutter Advanced which is only 7%, but stronger products are supposed to be available in Europe and Australia (eg Autan Repel Army 20). Otherwise, you may be able to do homemade PMD repellent if you have lemon eucalyptus oil. This paper dissolved it in coconut oil and tested it in Ethiopia (pubmed ID 12672146):
www3.interscience.wiley.com/cgi-bin/fulltext/104085667/PDFSTART

You could combine the best repellent locally available with treated clothing (either BUZZ-OFF or treated yourself w/ permethrin). I would think that would be enough but if you are still worried you could get the DEET shipped to you.

-Matt

africnow

Hi Matt,

Thanks for the details. I am not having it shipped for use here but for my trip this August to Kenya and Tanzania.

I will however check on whether 20% picaridin is available as you suggest.

Thanks!

sandi

August is winter in East Africa. Cold nights and mornings (the mosie biting time) = no mossies (or few). So, too if at higher altitude, the mossies don't fly this high.

During daytime, temps will be mild, in the 60s or low 70s. So unless protecting yourselves from possible Dengue mossies that bite during the day, I'm sure you'll be fine with the 30% Deet.

Kavey

Thanks Matt!
We have enough of the 50% stuff left for at least one more trip but I'm making a note of all this for the next time I need to buy some more!

africnow

Hi,

This is what my safari organizer wrote in answer to my question about weather in mid-August: &quot;On Ngorongoro Crater Rim it may be 4 Celsius just before dawn and down in the Crater 30 Celsius at 2.30 pm - if the sun's out. So be prepared for that range&quot;.

So I do want to be prepared for the mosquitoes too.

What would the British Fodorites say is the best DEET/Picaridin preparation available, please?

Thanks again!

pixelpower

Africnow,

Only the female mosquitos bite (and spread Malaria). And they only come out at night. Read; you need to be in an area where it's warm AT NIGHT to become &quot;mosquito-meat&quot;. ;-)

africnow

Yes, pixel we will be...

sundowner

I was working in my backyard yesterday and we have more mosqitoes than I've ever seen in Africa. And that includes the Delta in Bots.

I sprayed with Deep Woods Off that contains 25% Deet. About 3 hours after I applied it I felt a mosquito bite so I reapplied. After about another 2 hours I was worn out so I went inside. I ended up with 2 bites.

So that is my experience with 25% Deet. Also remember when using high Deet content sprays that it will ruin plastic, rubber, nail polish etc (watches, cameras, manicures, pedicures!).

jasher

Hello,

For those in the UK: PMD is the active ingredient in Mosi-Guard, which can be bought at Boots.

Cheers,
Julian