West Nile Virus Detected in Ohio Mosquitoes

June 19, 2002

COLUMBUS - The first pool of Ohio mosquitoes to test positive for West Nile virus (WNV) in 2002 has been confirmed, the Ohio Department of Health (ODH) announced today.

The positive mosquitoes were found in a trap set May 28 in Garfield Heights, Cuyahoga County, according to Dr. Richard Berry, chair of Ohio?s WNV Workgroup and chief of ODH?s Vector-borne Disease Program. The trap contained 919 Culex mosquitoes and the virus was detected in a pool of 50 Culex mosquitoes, he said.

Prior to today?s results, only New Jersey had found WNV in a mosquito pool in 2002.

Berry said finding the virus in mosquitoes this early in the year indicates the virus is spreading in Ohio. Other mosquito-borne illnesses, such as St. Louis encephalitis and La Cross encephalitis, generally aren?t detected in mosquitoes until July. "The Ohio Department of Health and its public health partners are monitoring the situation and working to reduce mosquito populations in Ohio," Berry noted.

"Ohioans should remember that less than 1 percent of mosquitoes carry WNV, even in an affected area. Only about one in 150 people bitten by an infected mosquito will become severely ill," Berry said.

Primarily a wild-bird disease, WNV is a mosquito-borne virus which generally causes mild symptoms that mimic the flu in humans. In rare instances, however, WNV can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the covering of the brain and spinal cord) in humans. This happens in less than 1 percent of people bitten by an infected mosquito. People over the age of 50, the very young and those with compromised immune systems are most susceptible to the serious complications related to the virus.

WNV was first detected in Ohio in August 2001 in a Lake County blue jay. By the end of summer, the virus had been detected in 54 blue jays and 226 crows around the state. In 2002, ODH has found WNV in nine crows and six blue jays in 11 counties.

"We ask that residents follow the Ohio Department of Health guidelines and work with their local health departments to help protect themselves and their loved ones from West Nile virus," Berry said.

West Nile Virus Background

The statewide West Nile Virus Workgroup, consisting of representatives from ODH, the Ohio departments of Natural Resources and Agriculture, Ohio Environmental Protection Agency, and federal and local partners has been working since 2000 to develop a statewide West Nile virus plan. As part of the planning, a statewide surveillance program was instituted that helped detect the disease and includes guidelines for mosquito control. Mosquito spraying is done on a local basis.

Prior to August 1999, West Nile Virus had never been reported in the Western Hemisphere.

Outbreaks of the West Nile virus occurred in Egypt, Asia, Israel, South Africa, and in some parts of Europe and Australia. West Nile was first found in the United States in New York City in the fall of 1999. During that outbreak, 62 people, including 46 residents of New York City, became ill. Seven people died of West Nile virus-related infections during this initial outbreak. Through 2001, there were 149 human cases, with 18 deaths.

West Nile virus is spread to humans by the bite of an infected mosquito. When a mosquito bites a bird that carries the virus, the mosquito becomes infected. Once a mosquito is infected, it may transmit the virus to people or animals when it bites them. Many birds can be infected, but crows and blue jays are most likely to die from the disease. Horses are also prone to West Nile virus infection. People cannot get West Nile virus directly from another person who has the disease.