Submitted by Geoffrey Ankeney, MD, Kaiser Permanente Olympia Medical Center
The sun has finally decided to grace Thurston County, which means it’s actually summer. Everyone is getting in on the fun! Unfortunately, ‘everyone’ includes bugs.
The most annoying of these summer friends is mosquitoes. The name derives from Spanish for “little fly.” And they are, technically, just flies. They’re also parasites that are particularly well-adapted to sucking blood from their hosts. In fact, the prestigious journal Nature published an opinion stating that mosquitoes are good at nothing else in nature with the singular exception of acquiring blood from other organisms.
It’s only the female that sucks blood; the males are happy with nectars and other plant juices. And nobody’s safe: mosquitoes will suck the blood of all kinds of mammals, birds, reptiles, even some fish. In all cases, the amount of blood taken causes no harm to the host. The problem is that the insect needs to inject saliva, filled with proteins, to successfully steal the blood.
You may be wondering, “Why do you gotta spit on me when you’re ALSO stealing my blood?” The answer gets back to the Nature article, which pointed out that mosquitoes are REALLY good at this. Female mosquito saliva has a protein that inhibits blood clotting, another that inhibits platelets, and one that causes vasodilation, or dilating the veins. One thing the proteins in mosquito saliva do NOT stop, unfortunately, is release of histamine from activated mast cells, which then cause the itchy bumps on the skin.
Here’s a fun fact: there’s a name for that skin reaction: “Skeeter Syndrome.” No joke. You can even find it in the medical literature. But skeeter syndrome isn’t the real problem with mosquitoes, it’s the diseases that can be carried in that nasty saliva the bug injects into our blood stream. Everything from Malaria, to yellow fever, Chikungunya, West Nile, dengue, filariasis to Zika, they all end up in our bodies thanks to mosquitoes.
You might think these don’t apply to our fine yards here in Washington, but don’t be too sure. There are over 40 different mosquito species in this state, and diseases have been found in them including West Nile virus, western equine encephalitis and St. Louis encephalitis. There are only two kinds of mosquitoes that carry Zika, and a similar number carry malaria, and none of them are found in Washington, thankfully. Yet. But they can always show up.
So how do we protect ourselves from this great menace to urban society? We could go with Lewis and Clark’s approach on their trek to the Northwest, and smear ourselves with hog lard (not kidding, look it up). And some people suffer more than others. It’s true that mosquitoes are mini-hematologists, which means they like Type O blood more than the others. Heavy breathing also attracts the bugs, because they can sense carbon dioxide in the air, as well as skin bacteria because mosquitoes are highly sensitive to odors from perspiration. There are 72 odor receptors on mosquito antennaes, and 27 of them are devoted to detecting sweat chemicals.
So aside from avoiding exercise so as to keep your breathing to a bare minimum (advice no physician should give), you’re left with bug spray as your main line of defense. There are other implements, like ultrasonic devices, citronella torches and others that may be useful, but have never been proven to work. Same for a long list of natural repellents like wormwood, sagewort, lemon balm, lemon grass, peppermint, cedar oil, camphor, tea tree oil and many, many more. Some may work, many do not, none have conclusive evidence that they work.
The synthetic repellents tend to work better, with the chemical DEET (N,N-diethyl-m-toluamide) leading the way. It has been proven to be effective, though it doesn’t last as long as most people think. It needs to be reapplied about every 2-3 hours to work. You can also use a chemical called permethrin on clothing, gear and bed nets. DEET probably isn’t the greatest chemical to have in your system, which is why most authorities recommend the spray formulation instead of the creams that you rub into your skin. DEET in general doesn’t appear to be dangerous, though it has been associated with minor adverse effects in outdoor workers who used it daily for long durations.
Therefore, given the risks of everything from “Skeeter Syndrome” to Zika, currently the best bet for enjoying summer evenings in the Great Pacific Northwest is to use a good insect repellent spray containing DEET. One day, Science Magazine may lead the charge to totally eradicate mosquitoes from the face of planet earth. Until then, these “little flies” will be enjoying summer right there with us.
