Communicable Disease

New Report Examines 2002 West Nile Virus Outbreak in Kent County

FOR IMMEDIATE RELEASE
February 25, 2003

For additional information contact:
Michael Mullet, Community Relations Coordinator, (616) 336-2220

The Kent County Health Department today released a report on West Nile Virus (WNV) that examines the impact of the disease on Kent County in the late summer and fall of 2002. During the same time, the U.S. was coping with the largest outbreak of WNV to date, some 3800 human cases in 41 states.

The Epidemiological Profile of West Nile Virus in Kent County, Michigan, provides background on the virus, the 2002 U.S. outbreak, and profiles the 57 cases reported in Kent County. The report is available on the Kent County Health Department web site at www.accesskent.com/health. Among the findings in the report:

  • The majority of WNV infections are asymptomatic, however, up to 20% of those infected will develop mild illness referred to as West Nile Fever. Approximately one in 150 infections will result in severe neurological disease.
  • The most common severe complications of WNV infection are meningitis (inflammation of the membrane around the brain and spinal cord) and encephalitis (inflammation of the brain).
  • In Kent County, among persons diagnosed with WNV, 47% developed encephalitis, 30% developed meningitis, 19% developed both meningitis and encephalitis, and 4% had mild illness (West Nile Fever). There were four deaths from WNV in Kent County in 2002
  • In Kent County, the youngest person infected with WNV was six years old, while the oldest was 88. The average age for West Nile Virus cases in Kent County was 50. Sixty-seven percent of the cases were male and 33% were female.
  • Approximately 68% of the reported WNV cases occurred in residents living in the City of Grand Rapids. Entomological research has suggested that the Culex pipiens mosquito, the species primarily associated with transmission of WNV, is more likely to live and breed in urban and man-made habitats (sewer catch basins, old tires, standing water in cans or buckets) than in natural or rural environments.
  • The Health Department received nearly 4,000 citizen reports of dead birds during the summer of 2002. The peak in reports of dead birds occurred roughly two weeks before the first human cases of WNV, consistent with surveillance trends in other parts of the U.S.

The Health Department is actively planning for the 2003 WNV season. On February 11, Kent County health officials hosted an information meeting with health officers and environmental health specialists from 12 West Michigan public health departments. The purpose of the meeting was to review data and experiences from the 2002 outbreak, and to begin formulating regionally-oriented strategies for responding to West Nile Virus in 2003. Work groups will focus on public information, environmental control, and laboratory testing issues.

Already, health officials are reminding people of the need to reduce individual exposure to mosquitoes as a key means of reducing the risk of West Nile Virus infection. Personal protection is a two-pronged responsibility that includes minimizing personal exposure to mosquitoes (by wearing protective clothing, using DEET-containing insect repellent, and staying indoors at dusk and dawn when mosquitoes are most active), and environmental measures to reduce mosquito exposure (eliminating standing water in the yard and other outdoor areas, keeping grass and weeds mowed near the house, and ensuring that screens are in good condition).

Additional information on West Nile Virus and reducing personal exposure risk can be found on the web sites of both the Michigan Department of Agriculture (www.michigan.gov/mda) and the U.S. Centers for Disease Control and Prevention (www.cdc.gov).

The Epidemiological Profile of West Nile Virus in Kent County, Michigan, is available on the Kent County Health Department web site at www.accesskent.com/Health.

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