Prevention

• Personal prevention methods
• Vaccines
• Large-scale prevention methods
• Surveillance/ Infection Control
  

Personal prevention methods

In areas where West Nile or West Nile-like virus are found, take the following precautions to reduce the risk of getting bitten by infected mosquitoes:

• Wear light-coloured clothing, full-length pants and long-sleeved shirts
• Use mosquito repellent containing DEET (N,N-diethylmethyltoluamide). DEET–containing repellents are the most effective, and the higher the concentration, the longer period of protection time. Repellents can irritate the eyes and mouth; avoid applying them to the hands of children.
• Remain indoors when mosquito levels are high – especially at dawn, dusk and in the early evening
• Remove pools of standing water from your property as they can provide excellent breeding grounds for mosquitoes, which in turn spread the virus
• Travelers should find out about outbreaks before traveling to areas where viral encephalitis is more common

Vaccines

There is no vaccine available against the West Nile virus or the West Nile-like virus.

There is a vaccine available against the Japanese encephalitis virus.

Large-scale prevention methods

Large-scale prevention methods against the West Nile virus involve raising public awareness and controlling the virus-carrying mosquito population.

Public education should include informing the public in affected areas about the disease, how it is transmitted, and how to avoid infection (personal prevention methods).

Controlling mosquito populations can be carried out through the use of pesticides.

In New York City, public health authorities have acted swiftly to contain the virus. Aerial pesticide spraying and public education programs have helped to reduce the risk of infection from West Nile-like virus in the city.

Surveillance/ Infection Control

Surveillance is a vital tool for preventing and dealing with outbreaks. Through surveillance, population densities are monitored, infection rates of the disease vectors are determined, and surveys are conducted. If much is known about a particular disease and how it is spread, public health measures can detect risks before outbreaks occur. This not only saves lives, but also reduces the costs associated with dealing with an outbreak.

Large-scale surveillance of bird and mosquito populations can provide information about where the virus is found, and how quickly it is spreading.

Surveillance measures can also be conducted on human populations. The New York City Health Department, with the aid of the CDC (Centre for Disease Control), is carrying out an a voluntary community survey to find out more about the disease carried by the West Nile-like virus. By gathering and analyzing blood samples, the department hopes to answer questions about the virus and its related disease, such as: “Who is at the highest risk of exposure?”, and “What proportion of people who got infected with the virus actually became ill?”. Blood samples will be tested for antibodies to the virus. The presence of these antibodies indicates that an individual has been exposed to the virus. Exposure to West Nile-like virus does not always lead to an encephalitis infection. In fact, most people who have been infected with the virus do not develop encephalitis.

Other key issues to keep in mind when surveying a disease such as mosquito-borne encephalitis involve environmental factors that affect mosquito populations. Factors such as heavy rainfall and subsequent flooding, higher-than-normal temperatures (including global warming), irrigation, and others can contribute to the spread or reemergence of the disease.

For more information about actions taken in New York, please link to the New York City Department of Health - Office of Public Affairs or the CDC, Office of Communication.