How to Protect Yourself from West Nile Virus and EEE

West Nile virus is the most common mosquito-borne disease in the United States—and this summer, cases are rising unusually early. According to the U.S. Centers for Disease Control and Prevention (CDC), the country has recorded its highest number of West Nile cases this early in the season since 2004.

Even more concerning, 38 of those 48 cases reported as of June 30 involved severe neurologic disease. Fewer than 1% of people infected with West Nile usually develop these complications, but they can lead to permanent disability or death.

Mosquitoes carrying West Nile virus have already been detected in nearly half of U.S. states this summer. Most people infected with West Nile virus never feel sick, but about 1 in 5 develop symptoms such as fever, headache, body aches, joint pain, vomiting, diarrhea, or a rash. Adults 60 and older and people with certain underlying health conditions face the greatest risk of severe illness.

The early surge in West Nile cases may be linked in part to this year's warmer and drier conditions.

“The house mosquito, the primary vector for the virus, breeds in stagnant, nutrient-rich water that can become concentrated during dry conditions,” explained Telford, who is also a commissioner for the Central Massachusetts Mosquito Control Project and a member of the state Mosquito Advisory Group. “Drought can also concentrate birds—the primary hosts of the virus—around remaining water sources, increasing contact between birds and mosquitoes. Warmer temperatures, meanwhile, can encourage mosquitoes to feed more frequently.”

Another mosquito-borne threat is Eastern equine encephalitis (EEE), the deadliest insect-borne viral disease in North America. Although only about seven people contract EEE each year in the United States, about one-third of those infections are fatal, according to the CDC.

Initial EEE symptoms typically resemble those of the flu, with infected people experiencing fever, chills, headache, and body aches. However, the illness quickly can progress to cause encephalitis—inflammation of the brain that can lead to coma, convulsions, or death. Many of the patients who survive the initial encephalitic symptoms of the disease will wind up with permanent neurologic damage, which itself may prove fatal within a couple of years.

There are no approved human vaccines nor specific antiviral treatments for West Nile virus or EEE, only supportive care, so “the key to staying safe is protection,” said Telford. He offered these tips to protect against West Nile virus and EEE:

Always wear mosquito repellent. Use a repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus on exposed skin and/or clothing. Always follow the directions for use on the package.

To further repel mosquitoes, you can also wear clothing treated with permethrin. If you do, be sure to keep permethrin spray and still-wet treated items away from cats, as the chemical is highly toxic to them; once dry, treated clothing should pose little risk to felines.

Avoid being outdoors between dusk and dawn, when mosquitoes are most active. Be sure to also avoid shady areas, which tend to attract mosquitoes—and their bites—during daytime hours. If that’s not possible, wear long-sleeved shirts and pants in addition to using a repellent. Loose clothing is best, as mosquitoes can bite through thin, tight material such as athletic leggings.

Take extra precautions for children and infants. Children under 15 are among those at greatest risk for severe forms of EEE, so be sure their arms and legs are covered when playing outdoors. If bringing a baby outdoors, cover a stroller or playpen with mosquito netting.

If you want to sit on your deck, use a large electric fan—or, better yet, two—and sit in the breeze. “Mosquitoes cannot fly against the wind,” Telford said. “Citronella candles will not prevent mosquitoes from finding you. There are some vaporizing insecticides that are being sold; theoretically they will work, but these have not been scientifically tested.”

Get rid of all sources of standing water outdoors. Turn over or empty containers where water may collect, from ceramic pots, to barrels and recycling bins, to pool covers. Clean clogged roof gutters and litter debris from along curbs to let stormwater drain.

Fix holes in screens. Make sure they are tightly attached to doors and windows.

When it comes to West Nile virus and EEE, Telford said only older mosquitoes contain virus, as the insects have to feed at least once to get infected. State or local mosquito-control projects may spray insecticide from trucks or by air to try to knock down flying mosquitoes with the aim of killing these riskier older ones.  

“All state-sponsored spraying is done after dark to minimize impacts on pollinators,” Telford said, noting that advance warning is typically provided by towns via their emergency messaging or online message boards.  

“Beekeepers should be alert for such messages and cover their hives during a spray event,” he added. “The insecticides that are used do not persist long in the environment. Studies that I have done suggest that although all insects are generally impacted, by three days after the spray event they have generally recovered to the pre-spray levels.”  

This is why mosquitoes sometimes still will be seen after a spray—they are new ones that have emerged from breeding sites and are not likely to be infected.  

“Spraying is a last resort,” Telford said. “Those of us involved in making such decisions weigh the temporary impact to the ecosystem against the possibility of people getting a potentially serious disease—and make that decision when all the indicators are that we would be irresponsible to not spray."

(Newswise/HG)