Sentinel Chicken in Cloverdale Tests Positive for West Nile Virus

Release date: 
Sep 20

Cotati, CA -  The Marin/Sonoma Mosquito & Vector Control District (District) announced today that a sentinel chicken from Cloverdale has tested positive for West Nile virus (WNV). The location of the chicken coop where the sample was taken is in the vicinity of Asti Road and Citrus Fair Drive in Cloverdale. 


In California, sentinel chicken flocks have been used as an effective disease surveillance tool for over 40 years. The District currently maintains sentinel chicken flocks in Marin and Sonoma counties as part of an integrated vector management program. Blood samples are collected every other week and submitted to the California Department of Public Health Vector-Borne Disease Laboratory, where they are tested for the presence of antibodies to WNV and other vector-borne diseases.   


Culex mosquitoes have the ability to spread WNV. The District routinely sets adult mosquito traps in the vicinity of all sentinel chicken flocks, and Culex mosquitoes are collected and tested for WNV. In this case, the number of Culex mosquitoes trapped at the location of the chicken flock has dropped significantly over the past three weeks.    


"Vector Control Technicians are checking all known mosquito sources in the area," said Eric Engh, Education Program Specialist for the District. "Additional adult mosquito surveillance traps will be set in the area surrounding the sentinel chicken flock to further monitor the abundance of mosquitoes and virus activity, and the sentinel chickens will continue to be tested every two weeks," stated Engh.       


Residents can help reduce the threat of WNV in the following ways:

  • Eliminate standing water in rain barrels, old tires, buckets, kiddie pools or any other item that can hold water for more than a week.
  • Report mosquito problems, neglected swimming pools, or any area that could be producing mosquitoes.
  • Stock backyard ponds or other permanent water features with mosquitofish. The fish are free and can be delivered or simply picked up at the District office.
  • Report dead birds to the West Nile virus hotline at 1-877-968-2473.
  • Wear mosquito repellent when outdoors during dusk and dawn. Use a repellent containing one of the following active ingredients: DEET, Picaridin, oil of lemon eucalyptus, or IR3535.

WNV symptoms may include headache, fever, body aches, vomiting, nausea, swollen lymph glands and skin rash on the chest, stomach and back.

  • Approximately 80% of people who become infected with WNV will not show any symptoms.
  • Approximately 20% of infected individuals will develop West Nile fever.
  • Less than 1% of infected individuals may develop a more severe form of illness with symptoms such as high fever, headache, neck stiffness, disorientation, coma, paralysis and in extreme cases, death.   


For more information or to report mosquito problems contact the Marin/Sonoma Mosquito & Vector Control District at 1.800.231.3236 or visit Report dead birds to the West Nile virus Hotline at 1-877-968-2473 or online at 

The Marin/Sonoma Mosquito & Vector Control District is an independent, special district committed to protecting public health from mosquitoes and mosquito-borne diseases. All programs and services are funded through property taxes and are provided to all residents of Marin and Sonoma counties. For more information about us please visit our website at  or call 1-800-231-3236.