State Health Department Announces West Nile Virus Detected In Mosquitoes and Four More Birds

Mosquito Pools from Westchester and Suffolk Counties Test Positive for West Nile Virus

Albany, July 17 – New York State Health Commissioner Antonia C. Novello, M.D., M.P.H., Dr. P.H. today announced that the State Health Department for the first time this year has identified preliminary evidence of West Nile virus in mosquitoes by using a rapid, highly sensitive DNA PCR molecular technique.

The finding of positive mosquitoes given the previous discovery of infected birds in Rockland, Westchester and Suffolk counties, New York, and Bergen County, New Jersey, is not surprising. The pools of mosquitoes that tested positive were submitted by Westchester and Suffolk counties the second week of July, and included pools of Aedes japonicus and a mixed Culex pipiens/restuans complex.

In addition, four more American crows tested positive for West Nile virus. Two crows were from Staten Island and another two came from Clarkstown, Rockland County. This brings the number of birds testing positive for West Nile virus to 19 for the year (16 confirmed and three presumptive, including 14 American crows, three blue jays and two red tailed hawks.) Eleven of the birds are from Rockland, three are from Suffolk, three are from Westchester and two are from Staten Island. To date, the Health Department has tested specimens from more than 700 birds of different species, more than 14,500 pools of mosquitoes from different regions and more than 200 humans. There have been no positive human cases so far.

Dr. Novello also indicated that due to the evidence of West Nile virus in both New Jersey and New York that she has contacted the federal Centers for Disease Control and Prevention to discuss a multi–state, regional approach to prepare a plan of action to fight the disease.

"The elaborate surveillance and prevention efforts mounted at the State and local level are, and have been, crucial." Dr. Novello said. "The findings reported here reinforce the importance of the public health efforts being taken to reduce and eliminate mosquito breeding sites through public education and prevention efforts. Individuals need to remain vigilant, however, regarding their personal protection and their exposure to mosquitoes at times when they are active or in large numbers – this time during the daytime, as well as at night."

This is the first time that the virus has been isolated from the Aedes japonicus mosquito. This Aedes japonicus mosquito originated in Asia (Japan, Korea) and is suspected to have arrived in the Northeast in the past few years in shipments of used tires. Since then, it has spread rapidly in Connecticut, New Jersey and New York. Its role in the transmission of the West Nile virus is unknown at this time. Aedes japonicus, different from Culex pipiens, is likely to be a daytime feeder and found in wooded areas. Larvae are found in small water containers such as rock holes, discarded tires or other containers.

Health officials also encourage people to try to avoid being bitten by mosquitoes. Culex mosquitoes are most active and feed between dusk and dawn. Aedes japonicus, however, different from Culex pipiens, is active both in day time and night time. In spite of these differences, the measures of surveillance regarding West Nile virus should be continued, including personal protection during outdoor activities around wooded areas and during evening hours.

In addition, personal protection measures should be followed, including wearing shoes and socks, long pants and a long–sleeved shirt when outside for a long period of time will be essential. Applying a mosquito repellent containing DEET should also be considered to prevent mosquito bites. Additional adult mosquito control measures are being discussed between the State, counties, and CDC.

Following are reminders of important ways to reduce breeding sites of the mosquitoes associated with transmission of West Nile virus:

  • Replace or repair broken screens and install new screens as needed;
  • Dispose of tin cans, plastic containers, ceramic pots or similar outdoor items that hold water;
  • Remove all discarded tires from your property;
  • Drill holes in the bottoms of recycling containers that are kept outdoors;
  • Clean clogged rain gutters and make sure they continue to work properly;
  • Turn over wheelbarrows and wading pools when not in use;
  • Change water in bird baths at least every four days;
  • Clear vegetation and debris from the edges of ponds;
  • Clean and chlorinate swimming pools, outdoor saunas and hot tubs;
  • Drain water from pool covers; and
  • Use landscaping to eliminate low spots where standing water accumulates.

More information about West Nile virus, personal protection measures, dead bird reporting and New York State's "Fight the Bite" campaign is posted on the State Health Department's website (

7/17/00–85 OPA