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posted on September 05, 2012 14:36

While the number of national cases of West Nile virus continues to set records, the number of human cases of West Nile virus in Idaho also is increasing, raising concern from public health officials about the growing number of people becoming sick from mosquito bites. 

Idaho currently has eight reported cases of West Nile infection, with five additional reports of illness under investigation.

Idaho’s eight human cases include three people who contracted serious neuroinvasive illnesses. The state’s human cases are in several counties:

  • Two people from Twin Falls County
  • Two in Elmore County
  • Two in Gem County
  • One in Payette County
  • One in Washington County

**UPDATE: The case in Washington County has been reclassified as a Payette County case, based on the residence of the person who contracted West Nile. So there are two cases in Payette County and none in Washington County.

Five horses also have tested positive for the virus – one each in Owhyee, Washington and Canyon counties, and two in Gooding County. Counting mosquito pools that have tested positive, so far 10 Idaho counties have found evidence of West Nile virus.

“It is very important that we all prevent mosquito bites and take protective measures, such as wearing repellent and reducing mosquito breeding habitat around our homes,” says Dr. Leslie Tengelsen, Deputy State Epidemiologist. “We expect transmission of the virus to continue until a hard freeze, which we anticipate will occur in October for much of Idaho.”

West Nile virus is usually contracted from the bite of an infected mosquito; it is not spread from person-to-person through casual contact. Symptoms of infection often include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach, and back. In some cases the virus can cause severe illness, especially in people over the age of 50.

Nationally, the Centers for Disease Control and Prevention reports almost 2,000 human cases, which is the highest number of cases in the nation since West Nile was discovered in the United States in 1999.  This year, Texas has been the hardest hit, with 888 human cases, followed by South Dakota, Oklahoma, Mississippi and Michigan. All 48 states of mainland United States have reported West Nile activity, with West Nile contributing to 87 deaths nationally.  Last year, three Idahoans were reported with WNV infections. In 2006, Idaho led the nation in West Nile illnesses with almost 1,000 infections, which contributed to 23 deaths.

To reduce the likelihood of infection, people are advised to avoid mosquitoes, particularly between dusk and dawn when mosquitoes are most active. In addition, you should:

  • Apply DEET or other EPA-approved insect repellent to exposed skin and clothing. Carefully follow instructions on the product label, especially for children;
  • Cover up exposed skin when outdoors; 
  • Insect-proof your home by repairing or replacing screens; and
  • Reduce standing water on your property. Check and drain toys, trays or pots which may hold water. Change the water in bird baths and static decorative ponds weekly as they may provide a suitable mosquito breeding habitat.

West Nile virus does not usually affect domestic animals, but can cause severe illness in horses and certain species of birds. Although there is no vaccine available for people, there are several vaccines available for horses. People are advised to vaccinate their horses annually according to label directions.

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