By Mike Gervais
Register Staff

6-26-2008

A human case of West Nile virus has been identified in Tulare County, prompting public health officials from across the state to issue a warning to residents about the danger of recreating in mosquito habitats.
The California Department of Health announced late last week that a woman from Tulare County tested positive for WNV, the first human case recorded in California this year.
According to California Department of Health Director Dr. Mark Horton, the WNV victim was not hospitalized and is recovering.

“The first human West Nile Virus infection of 2008 underscores the importance of taking precautions to protect from mosquito bites,” Horton said. “Californians should use insect repellent and eliminate all sources of standing water that can support mosquito breeding.”
To date, WNV has been detected in 19 of California’s 58 counties, however the virus has been present in most California counties in past years. As of last summer more than 25 Californians had been infected with the virus and at least one death was recorded in Kern County.

“We have not had an infected bird this year” in Inyo County, said Inyo County Mosquito Abatement Manager Jerry Oser. “Typically our West Nile Virus season picks up about mid July” when the culextarsalis species of mosquito begins to hatch and breed in vigor in Inyo County.
But that doesn’t mean residents, livestock and birds are not at risk. “It wouldn’t be unheard of if someone got West Nile before July,” Oser said, adding that residents, especially those recreating outdoors around dawn or dusk, should be sure to wear mosquito repellant all summer long.
In past years in Inyo County all cases of WNV have been detected in either horses or birds. One human was infected in Mono County last year.
“Most individuals who are infected with WNV will not experience any illness,” said Oser. “Individuals 50 years of age and older have a higher chance of getting sick and are more likely to develop serious symptoms when infected with WNV.”
Oser also said that individuals with diabetes and or hypertension are at greater risk for serious illness if they contract the virus.
Many people who contract the virus do not experience any symptoms. According to the California Department of Public Health Web site, “Less than one percent (aboutone in 150 people) of individuals infected with WNV will develop severe illness.”
Severe symptoms of WNV may include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent.
In extreme cases, the virus can be deadly to humans and livestock.
Milder symptoms, which affect approximately 20 percent of those infected (about one in five people), include fever, headache, body aches, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach and back.
“Symptoms generally last for just a few days, although even previously healthy people have been sick for several weeks,” the California Department of Public Health Web site states.
Approximately 80 percent of people (about four out of five) who are infected with WNV will not show any symptoms.
People who are infected by the virus typically develop symptoms between three and 14 days after they are bitten by an infected mosquito.
There is no specific treatment for WNV infection. In cases with milder symptoms, people experience fever and aches that pass on their own. In more severe cases, people may need to go to the hospital.
Like people, most horses bitten by mosquitoes will not become sick with WNV. However, if a horse is infected with the virus, signs may include stumbling, circling, hind leg weakness, inability to stand, muscle tremors and death.
A vaccine to prevent WNV is available for horses and horse-owners should consult with a local veterinarian about WNV vaccine and other vaccines against mosquito-borne viruses, such as western equine encephalitis.
In Inyo County and the rest of the Eastern Sierra, WNV has been most prominent in birds. Local officials have found infected birds throughout the county in previous years.
“We have all the right ingrediants – we have the right mosquito vector and the right birds. The risk of West Nile Virus is there,” Oser said.
To protect themselves from WNV, residents are encouraged to:
• Avoid spending time outdoors when mosquitoes are most active, especially at dawn and dusk.
• When outdoors, wear loose-fitting long pants and long sleeve shirts and other protective clothing, as needed.
 • Apply insect repellent containing DEET, picaradin or oil of lemon eucalyptus, according to label instructions.
• Eliminate all sources of standing water on their property that can support mosquito breeding.
• Make sure that doors and windows have tight-fitting screens and repair or replace screens that have tears or holes.
• Become familiar with the symptoms of WNV – a rash, fever, muscle aches, weakness, headache or swollen lymph glands. Older people, and those with pre-existing medical conditions such as high blood pressure or diabetes, are more vulnerable, get more severe illness and take a longer time to recover. There is no specific treatment for WNV infection except general supportive care. Contact a physician immediately if WNV is suspected.
For more information about WNV and or to report high levels of mosquito activity, call Inyo County Mosquito Abatement at (760) 973-7853.