West Nile continues to spread

West Nile virus is continuing to spread through Montana, with people warned to be cautious especially now that nine cases have been confirmed in horses, including in Blaine County.

The Montana Department of Livestock has urged horse owners to protect their animals and be on the lookout for symptoms.

“We’ve had nine positive cases confirmed in the past five days, so the threat is definitely there,” state veterinarian Dr. Marty Zaluski said in a press release Wednesday.

The state has confirmed cases of West Nile in mosquitoes and horses in 17 countries, including Blaine and Hill. This is in a season with high numbers of mosquitoes widespread across the region, following an extremely wet spring and early summer then heavy rainstorms continuing through Thursday night.

The virus has no noticeable symptoms in 80 percent of humans affected — no confirmed cases in people have been found in Montana so far — but can cause illness including headache, body aches, joint pains, vomiting, diarrhea, or rash that can take weeks or months from which to recover.

Fewer than 1 percent of people with the virus could develop nervous system disorders which can cause permanent damage or death.

People are urged to use insect repellent, with repellent containing DEET recommended, and to wear loose-fitting, light-colored long-sleeved shirts and long pants to avoid being bitten by the insects. Draining standing water also will help reduce the number of mosquitoes around residences.

Pellets to put in standing water, which prevent the larvae from metamorphosing into adult mosquitoes, also are available.

The best way to avoid the virus is to stay indoors during dusk and evening, when the kind of mosquito that transmits the virus typically is out.

People can contact local mosquito districts for more information, or visit the American Mosquito Control Association website at http://www.mosquito.org/ or the Centers for Disease Control and Prevention website’s West Nile section at http://www.cdc.gov/westnile.

For horses, Zaluski said their owners should be familiar with signs of the disease, which include:

Loss of appetite;

Depression;

Fever;

Incoordination or weakness of the hind limbs;

Muscle twitching;

Convulsions, and

Inability to swallow.

“If you notice any of these, or other, unusual symptoms, contact your veterinarian,” Zaluski said in the release. “There is no direct treatment for the virus, but with early detection and supportive veterinary care, some infected horses will recover.”

A vaccination is available for horses, which requires a booster, and is normally administered in late spring.

The release said horse owners could contact their veterinarian to see if an application this late could help.

Seven of the nine horses infected had vaccination records, with six not vaccinated for West Nile and the other not having a current vaccination. Of those horses, four died or were euthanized.

The release said using insect repellents on horses might help owners get them through the rest of the mosquito season without infection.