Insect-borne diseases have long posed a challenge for armies fighting in tropical and semi-tropical regions far from home. And rising insect resistance to pesticides, along with a globally warming climate is expected to make such diseases even more of a concern in years to come.
In 2003, for example, 80 out of 225 US Marines serving in Liberia contracted malaria … which US Army General Douglas MacArthur called “this dreadful disease” during World War II.
Researchers at the US Department of Agriculture now are testing new ways to protect troops against illnesses like malaria, dengue fever, yellow fever and Japanese encephalitis, all of which are transmitted by mosquitoes.
Among the solutions they’ve been testing: compounds taken from the American beautyberry, jatropha, breadfruit and other plants.
At least one compound so far has reached the point where it’s ready to patent. Developed by chemists Kumudini Meepagala and Ulrich Bernier, this yet-undisclosed repellent is reported to be more active and three times longer-lasting than DEET.
Such discoveries could help protect troops not only against malaria-carrying mosquitoes but against pests like sand flies, found in the Middle East, Afghanistan and Africa.
“I was one of those guys deployed to Iraq in 2003,” said US Air Force Lieutenant Colonel Douglas Burkett, who’s a research liaison officer with the Armed Forces Pest Management Board. “I’m an entomologist. I know how to control sand flies, because I’ve read all the textbooks. The reality is, when we got there, nothing worked. Soldiers were getting between 100 and 1,000 bites per night from sand flies that were testing positive for the parasites that cause this hideous disease, leishmaniasis.”
Leishmaniasis currently can’t be prevented by any known vaccines or medications, and it often can’t be diagnosed until three or four months after someone has been bitten by a sand fly. The disease often leaves victims with disfiguring scars and can cause serious organ damage.
US Agricultural Research Service scientists are also testing a variety of new fabrics that can help protect troops from biting insects, either in the form of clothing or protective netting. Cotton uniforms treated with permethrin have been used since 1991, and researchers are now looking at combining that strategy with more durable, fire-resistant fabric.
Another goal is to develop a band that could be worn on the sleeve or collar to provide additional protection from bites.
“(O)ur ultimate goal is a stand-alone product, so even without the uniform, you can put the band on the sleeve or collar to protect that area for a long period, and it can be used again and again,” said chemist Kamal Chauhan.