A Twin Falls County woman in her 40s has tested positive for West Nile virus (WNV).  She is the first human case of West Nile fever reported in Idaho for 2012. The woman traveled to Valley County shortly before her onset of illness, and it is unknown in which county she contracted the virus. The woman has recovered from her illness.

Since mid-July, three Idaho counties in southwest Idaho-- Ada, Canyon and Payette counties—have reported West Nile virus activity in local mosquitoes.  “The positive mosquito pools and the state’s first human infection are good warnings for people to ‘fight the bite’ of mosquitoes no matter where you live,” says Dr. Leslie Tengelsen, Deputy State Epidemiologist. “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.”

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.

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.

For more information, please visit www.westnile.idaho.gov