RBC I Rio Blanco County is one of 14 counties in Colorado that have at least one confirmed case of the West Nile virus.
The Colorado Department of Public Health and Environment (CDPHE) confirmed on Aug. 10 that Colorado has seen a sharp increase in the number of cases of West Nile virus diagnosed since January.
That information was confirmed by Jennifer O’Hearon, the executive director of Health and Human Services for Rio Blanco County, who added that state law forbids the release of information that could lead to identifying the person infected such as sex, age or area of residence.
O’Hearon did say that it does not appear that the virus was contracted near any of Rio Blanco County’s lakes, but she did confirm that the method of infection was by mosquito.
O’Hearon added that it appears the mosquito was encountered in Rio Blanco County.
People, animals and mosquito pools have tested positive from the following counties this season: Adams, Arapahoe, Bent, Boulder, Denver, Douglas, El Paso, Gunnison, La Plata, Larimer, Mesa, Morgan, Rio Blanco and Weld. So far this year, 13 cases of human West Nile virus have been reported, including one death.
O’Hearon confirmed that the death was not in Rio Blanco County.
The CDPHE expects more cases to be diagnosed as the summer progresses. Public health officials advise Colorado residents to continue to take precautions against West Nile virus by using mosquito repellent with DEET and other methods to avoid mosquito bites.
Last year, 101 people in Colorado contracted West Nile virus and three died.
“Although we can’t predict how much more West Nile virus activity will occur this summer, we know the virus is present and that means people are at risk,” said Jennifer House, the state public health veterinarian.
To help prevent West Nile virus infection, follow the four D’s: 1) Drain standing water around your house weekly; remember to drain water from tires, cans, flowerpots, clogged rain gutters, rain barrels, toys and puddles; 2) Dusk and dawn are when mosquitoes are most active; limit outdoor activities and take precautions to prevent mosquito bites during these times; 3) DEET is an effective ingredient to look for in insect repellents; always follow label instructions carefully; and 4) Dress in long sleeves and pants in areas where mosquitoes are active.
For more information about West Nile virus, visit www.colorado.gov/pacific/cdphe/west-nile-virus.
There currently are four viruses in Colorado that are transmitted by mosquitoes.
These viruses are maintained in a bird-mosquito-bird cycle. Mosquitoes are infected by feeding on a bird with virus in its blood. The virus is transmitted to the new host in the mosquito’s saliva when the insect bites another person or animal.
Humans and horses are incidental dead-end hosts in that they cannot infect other mosquitoes. Person-to-person transmission does not occur
These viruses are prevalent from May to September, when mosquitoes are most abundant, but the risk to humans occurs primarily from August through early September.
Severe infections can result in permanent brain damage or death. Most deaths occur in persons older than 50 years of age.
There is no specific treatment for infection with these viruses except supportive care.
Which animals get infected with these viruses? There are native birds, which have no natural resilience, and horses,
Horses are susceptible to infection with WEE and West Nile viruses, but not SLE. Another virus, eastern equine encephalitis (EEE) is not found in Colorado, but could be a problem if a horse travels to the eastern U.S. These diseases do not seem to be specific to a particular breed or age of horse. Clinical signs in a horse can include lack of coordination or muscle control.
In 2001, the program expanded to detect West Nile virus. Western equine encephalitis (WEE) is distributed across the central and western United States. St. Louis encephalitis (SLE) is found throughout the continental United States. California encephalitis viruses are a group of several viruses found throughout the U.S.
West Nile virus historically occurred in parts of Asia, Eastern Europe, Africa and the Middle East. This virus was first detected in the United States in 1999 during an outbreak in New York City.
These viruses are transmitted to people and animals by bites from infected mosquitoes. Only certain species of mosquitoes carry the virus and very few mosquitoes actually are infected. In Colorado, these viruses are transmitted to people by a species called Culex tarsalis, a medium-sized mosquito that feeds in the few hours around dawn and dusk. During the day, they rest in shady, secluded areas, such as under porches, roof overhangs, tall grass, shrubs and storm sewers. They breed in almost any source of standing water, including irrigated fields, old tires, hoof prints, flowerpots, tree holes, or any puddle of water that lasts for more than a few days.
Most people who are infected with mosquito-borne viruses do not become ill and have no symptoms. For persons who do become ill, the time between the mosquito bite and the onset of symptoms, known as the incubation period, ranges from 5-15 days.
Two clinically different types of disease occur in humans: (1) viral fever syndrome, and (2) encephalitis, an inflammation of the brain. Symptoms of the viral fever syndrome include fever, headache and malaise. These symptoms persist for a about 2-7 days.
In rare cases, the virus can cause a more serious brain infection such as aseptic meningitis or encephalitis. These infections begin with a sudden onset of high fever and a headache, and then may progress to stiff neck, disorientation, tremors, and malaise.
An infected mosquito can bite any animal, but not all animals will become ill. As the reservoir host of these viruses, birds are most often infected, but other animals can be infected and become ill as well.
Mosquitoes acquire the viruses from wild birds. Infection has been reported in more than 70 bird species. With WEE and SLE, infected birds will not appear ill or die. However, West Nile virus is new to this country and does cause illness and death in crows, magpies, ravens and jays. American crows constitute the majority of birds reported positive for West Nile virus.
Components of the Colorado Mosquito-Borne Virus Surveillance Program, local health departments and the Colorado Department of Public Health and Environment have conducted a statewide mosquito-borne encephalitis surveillance program.
Chicken flocks are strategically placed throughout the state and are tested bi-weekly during the mosquito season.
Cases of encephalitis suspected of being caused by these viruses are physician-reportable conditions under Colorado law.
