Communicable Disease

West Nile Virus Health Advisories

VETERINARY HEALTH ALERT - August 21, 2002

From: David Kraker, R.S.
Director, Environmental Health

The Kent County Health Department is conducting increased surveillance of West Nile Virus (WNV) activity following the identification of sentinel birds found to be infected with WNV in Kent County. West Nile Virus is a vector-borne disease spread by infected mosquitoes. Although the risk of infection and illness among humans is generally low, anyone with exposure to mosquitoes is considered to be at risk for WNV infection. The risk of illness among other mammals is not yet defined, however, there have been three suspect cases of WNV among horses in three Michigan counties (not in Kent County).

In Kent County, eight dead birds have tested positive for West Nile Virus (the State is no longer accepting birds from Kent County for testing). The Health Department has received over 2000 reports of dead birds. Mapping indicates these reports are widespread with no clearly identifiable clusters. We also have received many reports of dead squirrels. To our knowledge, none of the squirrels have been tested for WNV

Available information indicates that mosquitoes of the Culex genus are the primary vector in the transmission of West Nile Virus. The Kent County Health Department has begun limited trapping and identification of mosquitoes. We have the capability to test mosquitoes for both St. Louis Encephalitis and West Nile Virus; the first group of Culex mosquitoes tested positive for WNV. Information on Culex mosquitoes indicates that:

  • They are primarily nighttime biters
  • Lay their eggs in stagnant pools of water
  • Over wintering adult mosquitoes can harbor the virus
  • Activity is greatly reduced in early fall as they prepare for dormancy

In order to reduce the exposure of livestock and other farm animals to mosquitoes, the Kent County Health Department recommends the following:

  • Pet and livestock watering containers be changed every second or third day.

  • Animals be moved upland or inside during the evening to reduce exposure to mosquitoes.

  • Use of approved insect repellents

  • Property owners reduce mosquito breeding areas by eliminating pools of stagnant water such as in buckets, discarded tires and containers, etc.

For more information about West Nile Virus, as well as other mosquito-borne infections that can affect livestock, visit the Health Department web site at: www.accesskent.com/Health. Follow the link to the CDC web site for information about West Nile Virus and St. Louis Encephalitis.

###