COLUSA, CA (MPG) – West Nile virus has been detected in a mosquito pool and a sentinel chicken in Colusa County, but no human cases have been reported locally as neighboring counties confirm their first human infections of the year.
Colusa Mosquito Abatement District Manager Dan Kiely said Monday, Aug. 17, the district mosquito pools for testing, with each pool containing 50 female Culex tarsalis mosquitoes.
“We have sent off eight of these collections for testing and so far, just one positive sample from within our district boundaries.” Kiely said.
The district also received a positive West Nile virus blood sample from one of its sentinel chickens. The flock serves as part of the district’s surveillance program, with blood samples collected every two weeks.
A dead bird was sent to a laboratory in Davis last week for testing, but the district had not received the results as of Monday.
Kiely said the district had not been notified of any human West Nile virus cases in Colusa County. However, conditions this year could lead to infections earlier than the district typically encounters them.
“Our district may expect to see an earlier than usual human WNV infection, due to the milder winter and spring months we have had this season,” Kiely said. “This allows for more disease transmission between the Culex tarsalis mosquito and our local bird population, which serves as the reservoir host for the West Nile Virus.”
Kiely added that human cases within the district remain rare and typically occur from mid-September through the end of October.
The activity in Colusa County comes as human infections have surfaced elsewhere in the Sacramento Valley.
Sutter County Public Health confirmed its first human case Aug. 17. Yuba County confirmed its first case Aug. 14, with the patient briefly hospitalized before recovering.
Butte County reported a more serious outcome Aug. 13 when public health officials confirmed the county’s first West Nile virus-related death of the year. The person, who was between 80 and 90 years old, died from complications related to the illness.
Statewide, California had recorded 30 human cases, including three deaths across 14 counties as of the end of last week, according to Sutter County Public Health. The number of cases was double the total reported at the same point last year.
West Nile virus spreads to humans and animals through the bite of an infected mosquito. Mosquitoes acquire the virus after feeding on infected birds.
Most people infected with the virus develop no symptoms. About one in five experience mild to moderate illness, which can include fever, fatigue and body aches. Fewer than one in 150 develop severe neurological illness such as encephalitis or meningitis. Severe cases can result in permanent disability or death.
The Colusa Mosquito Abatement District’s mosquito control program has been operated since late April and is scheduled to continue through the first week of November.
“To minimize the risk of mosquito borne illnesses we have tried to lower the large numbers of mosquitoes in our district, through our mosquito control program,” Kiely said.
Residents can reduce their risk by using mosquito repellent, taking precautions outdoors around dawn and dusk and eliminating standing water that can provide mosquito breeding habitat.
Additional information about West Nile virus and statewide surveillance is available at http://westnile.ca.gov.