Keep Your Proboscis To Yourself

At the risk of seeming like I'm "bugging out," I've got one more insect to talk about, that's the mosquito (See my articles about ticks and bees/hornets/wasps). In many ways, the mosquito can be considered the most dangerous animal in the world: it's found in every region on the planet except Antarctica, and these irritating insects are responsible for spreading diseases such as malaria, chikungunya, several types of viral encephalitis, elephantiasis, yellow fever, dengue fever, West Nile virus and Zika, which collectively afflict an estimated 700 million people and kill between 725,000 and 1M people per year. As the World Health Organization notes, more than half of the human population is currently at risk from mosquito-borne diseases. 

And while these bugs spread a huge number of diseases around the world, here in New England, the two big ones that we need to worry about are Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV)

Mosquitos, like ticks, are "vectors," meaning they transmit diseases from one species to another. Both EEE and WNV are primarily found in birds (host or reservoir), but the mosquitos can take a blood meal from the birds and then spread the disease to other animals when they take their next meal and inject their proboscises (mouth parts) and saliva into your skin. 

If that sounds gross, you'll want to see this up close, check out this video!

Fortunately, for the most part, EEE and WNV lead to mild or asymptomatic illness, meaning many people who are infected by either one will never know. But, in some people the diseases can lead to swelling and inflammation on the brain and central nervous system, and there are no effective treatments. For people who develop severe encephalitis from the EEE virus, there's a 30% mortality rate, and even the survivors can have long term neurologic disability. And while full symptomatic infections from WNV are also rare, it IS the leading cause of mosquito-borne disease in the continental United States, having outpaced other viral illnesses. 

Here's a little breakdown on the two.

Eastern Equine Encephalitis (EEE) 

  • People infected may have no symptoms, may develop fever, headache, nausea, vomiting approx. 1 week after bite—most will have self limiting illness
  • Approx 2% of infected adults and 6% of infected children will develop encephalitis 
  • Rapid deterioration leading to seizures, focal neurologic deficits, to coma
  • Specific diagnosis is made by analyzing cerebrospinal fluid (CSF) taken from a large needle inserted into the lumbar spine 
  • EEE has a 30% mortality rate, death can occur within 3-5 days after onset, and even in survivors, long term neurologic complications are common

West Nile Virus (WNV) 

  • The leading cause of mosquito-borne disease in the continental United States.  
  • Found in US in first 1999 
  • Can be fatal in birds and horses (horse vaccine available)
  • Most human cases are asymptomatic (80%), some people will have mild symptoms—fever, headache, joint pains, and body aches
  • Mild infection goes away on its own, but people can have weeks or months of fatigue and difficulty concentrating
  • Some (1/150) may develop frank meningitis or encephalitis—can be fatal (10%) or associated with severe and long-term neurologic symptoms 
  • Diagnosed by analyzing CSF (as above) although a blood can be helpful

As of this writing (August 12, 2023), I haven't seen or heard of any human cases of either one in New England, but health departments do routine monitoring of mosquito populations to see when the viruses are present. A few days ago, had an article about the fact that the risk of WNV is going up, and you can find the most up to date info for both EEE and WNV on your state's Dept of Public Health web site:

Mosquitos love warm weather, standing water, and blood. So far, this summer has provided plenty of the first two, and you provide the last item. Given that these pests are attracted to our body temperatures and the CO₂ we exhale, our best tools to prevent infection lie in the use of insect repellents that are high in active ingredients such as DEET and picaridin. The Washington Post just today published a good article discussing some of the DEET alternatives. 

My strategy at avoiding mosquito bites is a bit different, I just like to go out with people who are more attractive to them (in fact, I was going to take my wife out so I could get some of my own pics of mosquitos biting, but I didn't think she'd agree).

Anyway, for now, EEE and WNV are the only illnesses we really need to worry about in New England. Zika hit Florida and Texas a few years ago, and there have been a few cases of malaria in Florida and Texas as well. I'm sure as our weather and climate change, we'll likely see more of these illnesses spread.

So, on that note, just go faster than the mosquitos and get outside and enjoy some trails!

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Image #1: By CDC/ James Gathany - This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #18749.Note: Not all PHIL images are public domain; be sure to check copyright status and credit authors and content providers.العربية | Deutsch | English | македонски | slovenščina | +/−, Public Domain,

Image #2: By The Trustees of the Natural History Museum, London -, CC BY 4.0,