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Health officials urge precautions against mosquito-borne diseases as West Nile Virus activity is detected

State health officials are urging Hoosiers to take steps to protect themselves from mosquito bites after the West Nile virus was detected in Indiana for the first time this year.

So far in 2021, one mosquito sample collected in Vigo County has tested positive for West Nile virus. No human cases of West Nile virus disease have been detected so far this year; however, the Indiana Department of Health expects to see further West Nile activity throughout the state as the mosquito season progresses. 

“Many of us are looking forward to summer activities that were postponed or canceled last year, but we don’t want anyone to get sick from mosquito bites,” said State Health Commissioner Kris Box, M.D., FACOG. “Hoosiers in all parts of the state should take precautions to prevent mosquito bites whenever they are outdoors.”

Mosquitoes can transmit a variety of diseases. In 2019 and 2020, Indiana experienced outbreaks of another mosquito-borne disease, eastern equine encephalomyelitis (EEE). These outbreaks caused two human cases, one of which was fatal, and 18 horse cases in northern Indiana. Although EEE virus activity has not been detected in Indiana so far this year, health officials want Hoosiers to remain cautious.

State health officials recommend the following preventive measures:

  1. Avoid being outdoors when mosquitoes are active (especially late afternoon, dusk to dawn, and early morning);
  2. Apply an EPA-registered insect repellent containing DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol to clothes and exposed skin;
  3. Cover exposed skin by wearing a hat, long sleeves and long pants in places where mosquitoes are especially active, such as wooded areas;
  4. Install or repair screens on windows and doors to keep mosquitoes out of the home. 

Even a container as small as a bottle cap can become a mosquito breeding ground, so residents should take the following steps to eliminate potential breeding grounds:

  1. Discard old tires, tin cans, ceramic pots or other containers that can hold water;
  2. Repair failed septic systems;
  3. Drill holes in the bottom of recycling containers left outdoors;
  4. Keep grass cut short and shrubbery trimmed;
  5. Clean clogged roof gutters, particularly if leaves tend to plug up the drains;
  6. Frequently replace the water in pet bowls;
  7. Flush ornamental fountains and birdbaths periodically; and,
  8. Aerate ornamental pools or stock them with predatory fish. 

About 80 percent of people infected with West Nile virus will not develop any symptoms at all, but about 20 percent will develop an illness accompanied by fever, headache, body aches, joint pains, vomiting, diarrhea or rash. Fewer than 1 percent of people infected with West Nile virus will develop severe illness affecting the nervous system, which can include inflammation in the brain or the membranes that cover the brain and spinal cord. About one in 10 severe cases is fatal. People older than 60 years are at greatest risk of severe disease from West Nile virus.

While EEE virus disease is much less common than West Nile virus disease, it typically causes more severe illness. As with West Nile, some people infected with EEE will not develop any symptoms at all. Some people will develop an illness accompanied by fever, chills, joint pain or muscle pain. Some will recover from this illness without additional complications, but in others, the illness can progress to severe illness affecting the nervous system. About one in three severe EEE virus disease cases is fatal; however, patients who recover from severe illness often experience serious and permanent complications. People who are younger than 15 years and older than 50 years are at greatest risk of severe EEE virus disease.

People who think they may have West Nile virus or EEE virus disease should contact their healthcare providers.

To see the latest results of the state health department’s mosquito surveillance, go to https://gis.in.gov/apps/ISDH/Arbo/. To learn more about mosquito-borne diseases, visit https://www.in.gov/isdh/27793.htm.