West Nile virus found in humans in Colorado, Nebraska and Wyoming
For more information
For more information about West Nile Virus, go to http://www.cdc.gov/ncidod/dvbid/westnile.
Late summer is peak time for mosquitoes and since 1999, when West Nile Virus appeared in the U.S., August and September are also the time for mosquito-transmitted diseases.
According to data from the Colorado Department of Public Health and Environment, as of July 22 in Colorado, there have been four human infections of West Nile Virus in 2016. That’s not including the latest announcement of a human diagnosis of West Nile Aug. 4 in Weld County. In addition, on Aug. 5 the Colorado State University Veterinary Diagnostic Laboratory in Fort Collins diagnosed the first horse in Colorado with the disease.
Though there are currently no vaccinations or treatments available for humans, there are options for horse owners. A West Nile vaccine is affective if administered properly with boosters each year, according to a news release from the Colorado Department of Agriculture. However, trying to prevent the infection in the first place is also key to keeping animals healthy.
“Strict insect control is an important factor to inhibit the transmission of West Nile Virus,” said Keith Roehr, state veterinarian, in a news release. “I encourage livestock owners to keep an eye out for standing water for mosquito populations.”
If a horse is infected with West Nile Virus, they may or may not show clinical signs of encephalitis, according to the Nebraska Department of Agriculture. Some of these symptoms include appetite loss, depression, fever, muscle quivering and weakness of limbs, among others.
So far in 2016 in Nebraska, there have been eight human cases of West Nile, and no discovered equine cases. In 2002, a massive West Nile Virus outbreak infected 1,100 horses from six weeks old to 34 years in every county of Nebraska, according to the Nebraska Department of Agriculture. One in three of those animals died.
To prevent infection in horses, don’t leave standing water around livestock, remove all discarded tires from the property and either properly ventilate or overturn containers left outdoors to keep them from gathering water. If ornamental pools are on the property, stock them with fish. Clean and chlorinate swimming pools.
Another tip from the Nebraska Department of Agriculture is to keep horses indoors at dusk and dawn, peak mosquito hours, and avoid turning the lights on in the stable during the night. To draw mosquitoes away from the horses, turn lights on around the perimeter of the stable. Keeping chickens and other birds away from horses can also keep equines safe, as birds are known vectors of the virus. Topical mosquito repellents for horses can also be used.
So far this year in Wyoming, there has only been one human case of West Nile Virus and no equine cases. Last year, there were eight human cases and four equine cases. Since West Nile first appeared in the state in 2002, though, the number of human cases have ranged from two to 393, according to a news release from the Wyoming Department of Health.
West Nile symptoms in humans typically appear anywhere from 3-14 days after the initial mosquito bite. Human symptoms include headache, body aches, joint pains, vomiting, diarrhea or rash, according to a news release from the Weld County Department of Public Health and Environment. About one percent of those infected with West Nile Virus develop a serious illness like meningitis or encephalitis, according to the release.
Since the highest number of West Nile infections typically comes in August and September according to the Colorado Department of Public Health and Environment, it’s important for people to remember the four D’s — Drain standing water, limit outdoor activities at Dusk and Dawn, use insect repellant containing Deet and Dress in long sleeves and pants.
In some areas, like Weld County, mosquito trap data shows seasonal highs for risk of human infection of West Nile. If a trap has a vector index of .75, that indicates elevated risk of infection. Two traps in Weld have come back with vector indexes of 2.75 and 2.38.
“It’s rare to see multiple WNV testing zones have such high risk to human health,” said Mark E. Wallace, executive director for the Weld County Department of Public Health and Environment in a press release. “It is hard to predict, but there may be increased human infection rates in late August and early September.” ❖
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