It’s Late Summer…Are Mosquitoes Still a Disease Threat?

By Chris Williams on August 14, 2014.

Mosquito landing on landNow that summer is winding down, maybe you think that the risk of mosquito disease transmission should be winding down as well. Sorry, but not yet. In our Northeastern region, mosquitoes are most likely to spread disease June through September. But the risk of mosquito-borne illness continues in an area until there is a hard frost that will kill all mosquitoes.

What Are the Mosquito Diseases in My Area?

In Massachusetts and New Hampshire, the mosquito-transmitted diseases that we need to worry about are West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE). Both are transmitted by the bite of an infected mosquito. Mosquitoes often pick up the diseases when they bite already infected birds.

  1. West Nile Virus – Most WNV infections do not cause any symptoms. A mild infection may result in fever, head and body aches, skin rash, and swollen glands. Rarely, people over 50 can have a more serious reaction. Since only individuals with symptoms are reported, it’s hard to know the actual incidence of this disease in our region.
  2. Eastern Equine Encephalitis – EEE is not as common in our region as WNV, but it is more serious. Symptoms include high fever, stiff neck, and headache. Swelling of the brain, called encephalitis, is a serious complication that can result in coma and death.

What’s the Risk of Getting One of These Diseases?

We’re lucky in New Hampshire and Massachusetts that the number of cases of WNV and EEE have been low for the past couple of years. Only a small number of mosquitoes are infected with either of these diseases at any one time, so being bitten by a mosquito does not mean you will get sick. Your risk of coming across an infected mosquito that could bite you also depends on the areas you frequent and how well you protect yourself from mosquito bites.

The latest Arbovirus Update (8/12/14) from the Massachusetts Department of Health and Human Services reports that the current risk level for EEE is remote to low in all areas of the state of Massachusetts. Small outbreaks of EEE reportedly occur in Massachusetts every 10-20 years; the last was in 2004. The risk of WNV in Massachusetts is presently low in all areas except the Boston environs where the risk is moderate.

For most of New Hampshire, as of July 1, 2014, there was no arbovirus surveillance data available. A few areas in the southeastern part of the state and one area in the southwestern part of New Hampshire showed low to moderate risk levels for WNV and EEE.

For more on protecting yourself from mosquitoes, see these earlier Colonial blogs:

Photo credit: James Jordan / Foter / Creative Commons Attribution-NoDerivs 2.0 Generic (CC BY-ND 2.0)



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