West Nile found in Blaine County mosquitoes

West Nile virus has been confirmed in the area, with Blaine County among Montana counties with mosquitoes testing positive for the virus.

Blaine County Health Department said in a Facebook post Monday evening that the virus was detected in Blaine and Phillips counties.

“Please take precautions when you are outdoors, utilize proper bug spray and clothing, remove sources of standing water, and vaccinate your horses if you haven’t already,” the post said.

A post on the Hill County Weed and Mosquito Control District Facebook page said Hill County’s last trap had 176 mosquitoes with 46 of the type that can transmit disease such as West Nile, and all tested negative for disease.

Chouteau and Liberty counties also have not had positive tests as of this morning, their health departments report.

The first positive test in Montana this year was in Dawson County, listed on the Hill County mosquito control district Facebook page Aug. 22.

Montana Department of Public Health and Human Services said in a release last Thursday that the virus was confirmed in Lewis and Clark County as well, and a case was confirmed in a horse in Lewis and Clark County.

“Mosquito season is West Nile season,” DPHHS epidemiologist Devon Cozart said in the release. “Detection of West Nile virus in mosquitoes means that it’s currently in Montana, so now is the time to make sure you’re taking precautions against mosquito bites.”

Most people who become infected with WNV experience no symptoms, but 1 in 5 develop a mild illness, with symptoms such as headache, rash, body aches, joint pains, vomiting or diarrhea, the release said. Other people, fewer than 1 out of 150, may become severely ill with encephalitis or meningitis — inflammation of the brain or surrounding tissues.

Serious infection in or around the brain is called neuroinvasive disease and is indicated by symptoms such as disorientation, convulsions, vision loss and numbness. If someone develops any of the mild or serious symptoms listed above, they should see their health care provider for evaluation and care.

No vaccine or targeted medication available for WNV infection exists other than supportive care, the release said. A WNV vaccine is available for horses, and horse vaccination is highly recommended. 

The DPHHS release urged people to protect themselves from the virus by following the four Ds of prevention, dusk/dawn, dress, DEET and drain.

People are urged to use special care during peak mosquito hours, from dusk to dawn. People should avoid outdoor activity in those times and, if outside, protect themselves from bites.

People should wear long-sleeved shirts and pants to reduce the amount of exposed skin and reduce the chance of being bitten.

People should cover exposed skin with a repellent containing DEET, which is the most effective against mosquito bites. Other repellents are available, including oil of eucalyptus and picaridin. Turner said a new repellant known as Moskito Care seems to be very effective and is attractive because it has a more pleasant smell.

The last “D” is drain. People are urged to drain any standing water on their property, make sure gutters drain properly and regularly change water in pet dishes and decorative items.

One cup of water can breed 250 mosquitoes, while a 5-gallon can half-full of water can breed 10,000 of the insects.

A particular problem is water in old tires. The combination of standing water and the heat generated in the tires speeds up the life cycle, with thousands of mosquitoes potentially hatching out in just a few days.

The rain and heat the area has experienced has allowed for mosquito eggs to hatch quickly, the Hill County mosquito control district post said.

“Our crews have been doing a fantastic job keeping the numbers down this season, despite our department being already short-staffed and impacted greatly by COVID-19 currently and over the last few weeks,” the post said. “ … All of these factors have presented a challenge for mosquito control operations, but we have a dedicated crew that have done great work all season long. The support from our community has also been incredible. Thank you, Hill County, for being there for us too! See you out there!

The Hill County mosquito control district post said its crews have been aggressively fogging sections of the district and will continue to do so, increasing frequency if West Nile is detected in the county.”