Mosquito surveillance has detected record number of mosquito samples which tested positive
for West Nile virus throughout the five boroughs
Health Department is increasing outreach and aggressively spraying parts of the city
where mosquito activity is prevalent; there have been seven rounds of pesticide spraying,
two aerial larvicidings and 1,200 ground-based larvicidings to date
August 11, 2017 — The Health Department today confirmed the first human case of West Nile virus of the 2017 season. The patient is less than 50 years of age with underlying medical conditions and is in serious condition at a Manhattan hospital. Human cases of West Nile virus occur each year in New York City, and most cases are identified between late July and October. While the mosquito population this year remains at an average level, West Nile virus activity varies year to year. The number of mosquito pools testing positive for West Nile virus has reached a record high at this point in the season – 337 mosquito “pools”, or a collection of mosquitoes captured in a surveillance trap, have tested positive this season. This could indicate a greater risk of infection and may result in a larger number of human cases relative to other years.
The majority of the positive samples have been detected on Staten Island; however, mosquitoes with West Nile virus have been found in every borough. So far this season, the Health Department has completed seven rounds of pesticide spraying and two aerial larvicide treatments to reduce the risk of West Nile virus. Additional mosquito treatments are planned for the remainder of the mosquito season with locations to be determined by the extensive and sophisticated citywide surveillance system. To educate neighborhoods about West Nile virus, the Department has enhanced outreach to at-risk communities – particularly in senior centers and other venues – in Staten Island and Brooklyn. Health Department staff will expand outreach to Queens this week and begin distributing free mosquito repellent in high-risk areas throughout the city. More information about the City’s mosquito control program.
“The findings from our mosquito surveillance are concerning and serve as a reminder for all New Yorkers that they can take simple precautions to protect themselves and their families from mosquito bites: wear mosquito repellent, cover your arms and legs when you are outdoors, get rid of standing water, and install window screens,” said Health Commissioner Dr. Mary T. Bassett. “We will not be able to completely eradicate West Nile virus from the mosquito population, but we can reduce human transmission and save lives.”
The West Nile virus was first detected in New York City 18 years ago. Since 1999, the number of human cases has ranged from three to 47 annually. Of the 317 West Nile virus cases overall, 38 (15 percent) have died due to their infection. The number of positive mosquito pools has also varied from 40 to 827. New York City has over 50 species of mosquitos, but West Nile virus is transmitted primarily by several Culex species, including Culex salinarius and Culex pipiens.
The Health Department has successfully helped control mosquito-borne diseases with regular mosquito surveillance throughout the early spring and summer. Currently, there are 121 surveillance traps in the five boroughs. The agency’s mosquito control efforts are data driven and rely on our mosquito trapping and testing results to determine areas of the city to spray pesticide and apply larvicide. The Health Department will increase spraying in neighborhoods that meet this criteria. Department employees use trucks or backpack sprayers to kill adult flying mosquitos.
Every year, as a part of normal outreach, the Health Department also conducts 80 to 90 presentations to educate communities about mosquito-borne illnesses. Community presentations on West Nile virus and other health topicse.
MEDIA CONTACT: Christopher Miller/Julien Martinez, (347) 396-4177