The Centers for Disease Control and Prevention (CDC) issued an advisory again this summer warning of the increased risks of mosquito-borne West Nile Virus, now a familiar enough, though unwelcome, summer visitor to warrant its own acronym -- WNV.
    West Nile Virus often has no symptoms or only mild symptoms, but one in about 150 infected persons develops a serious illness characterized by high fever, headache, a stiff neck, stupor, disorientation and other effects that can last for several weeks. Neurological damage can be permanent.
    Casual contact with an infected person does not spread WNV, and there is no specific treatment. People who spend a lot of time outdoors in the summer are more likely to be bitten by an infected mosquito. People more than 50 years old generally develop more serious symptoms.
    The best way to avoid being infected? Prevent mosquito bites, use repellents containing DEET (N, N-diethyl-meta-toluamide) particularly at dusk and dawn when mosquitoes are most active. Light-colored clothes and good window screening also help, and eliminating or replacing sitting water, found in places such as bird baths and children's wading pools.
    Reprinted here is an edited version of a WNV "backgrounder" initially published in Environment Writer's May 2000 issue.

As the weather warms and mosquito season moves into high gear, West Nile Virus is making headlines again. This year, the "never-heard-of-it" syndrome is no excuse for uninformed reporting. Media have an opportunity for more deliberate coverage and analysis of this emerging environmental disease.

For now, neither panic in the streets nor blasé inattention or inaction will be the antidote. Journalists instead can report the wealth of information that is known, in hopes of encouraging timely and effective public understanding and response.

West Nile Virus can make people sick or kill them. Seven people died in the 1999 Northeast outbreak that severely sickened 62 people. Some 3–15 percent of all cases are fatal, although fatalities are most likely among the elderly and those with weak immune systems.

But if the media approach WNV solely as a human health story, they may repeat the errors of the past in which environmental risks were viewed primarily from the perspective of potential cancer-causing impacts, but not a broader ecological standpoint. The public should understand that the impacts of the virus on wildlife can have systemic effects on entire ecosystems.

The virus is of news value, in part, because it is fairly new to the western hemisphere. It is passed along to humans from mosquitoes that have fed on infected birds, such as crows found throughout the United States. (Note: Crows do not pass the virus directly to humans.) http://www.cdc.gov/ncidod/dvbid/westnile/index.htm and http://www.cdc.gov/ncidod/dvbid/westnile/surv&control03Maps.htm

Return to Menu

1  What surveillance programs are being conducted in your area todetect West Nile Virus in humans? (Or for that matter, St. Louis encephalitis and other "notifiable" diseases.) What are the findings to date? What is the significance of the findings? Check with state and local health agencies and the CDC.

2  Take a look at the role birds will play in detecting the disease, alerting public health officials to hot spots and helping direct mosquito control operations. What types of birds can be infected by the virus and what effect could it have on migratory bird populations? Will migratory birds spread the disease to other parts of the hemisphere and other species of wildlife?

3  How should people handle dead birds? Who should they call? Can they touch them? What signs/symptoms should the public beon the lookout for?

4  What populations of birds or domestic animals and mosquitoes in your area could take part in the transmission cycle of West Nile Virus? Who is monitoring those animal populations and how effectively? Will it spread to warmer climates where it could become established as a year-round threat to wildlife, domestic animals, and humans?

5  Does your area have mosquito control and abatement programs, districts, or agencies? How effective are they? What other mosquito-borne diseases affect people or animals in your area? What mosquito-control methods are used, and are they preventive or reactive?

6  Is there a truck or aerial insecticide-spraying program in your area? What insecticides are used? What are the benefits and potential adverse effects? How, where, and when are the pesticides applied? What precautions should people take to avoid unnecessary or harmful exposure to pesticides being sprayed? Have government agencies and the media been effective in informing people about those precautions?

7  How can residents protect themselves from mosquitoes and best suppress mosquito breeding near their homes?

Return to Menu

West Nile Virus is primarily a disease of birds. It is commonly found in Africa, West Asia, and the Middle East but has also caused outbreaks in Europe. In humans, it can cause encephalitis, an infection of the brain. West Nile Virus is similar to the virus that causes St.Louis encephalitis, which for years has been found in the United States. West Nile had not been found in the United States before the late summer of 1999.

Most people infected by the West Nile Virus have no symptoms or experience something similar to flu. Symptoms of West Nile Virus may include fever, headache, achy muscles, and extreme fatigue, perhaps accompanied by a skin rash and swollen lymph glands. In a fraction of cases, fever leads to encephalitis, which is fatal in some cases or may cause neurological damage.

There is no vaccine for West Nile and no known cure. As with other viral diseases, treatment consists of support until it has run its course. The incubation period -- the time between an infectious bite and the onset of symptoms -- is usually 5 to 15 days.

Humans contract West Nile Virus largely from mosquito bites. Although some 150 species of mosquitoes are found in the United States, the primary transmitter of West Nile is Culex pipiens. The female mosquito catches the virus when she bites an infected bird and can then pass it along if she later bites a human. Humans do not get it from other humans or animals.

The virus can infect many different species of birds and other animals, but crows seem particularly vulnerable -- monitoring programs focus on them. In fact, birds were key to solving the 1999 outbreak. CDC epidemiologists identified the West Nile Virus and linked it to the human illness after pathologists found the disease in flamingos, herons, and bald eagles that had been dying at the Bronx Zoo. The virus has been found also in horses and a cat.

Return to Menu

The West Nile Virus and the encephalitis it can cause pose serious public health concerns, but journalists can best serve their audiences by keeping the risks in perspective.

Possibly the most newsworthy thing about West Nile Virus is merely that it is somewhat new -- not that it is an unusually large "big picture" threat to public health. Other mosquito-borne or insect-borne viral encephalitis diseases are found regularly in the United States.

It may be worth portraying deaths from West Nile in the context of other infectious diseases. CDC reported 66 human cases of severe disease and nine deaths in 2001 from West Nile Virus. By comparison, some 3,000 cases of bacterial meningitis occur annually in the U.S., despite the availability of vaccines. Some 10-13 percent of those patients die despite getting antibiotics, and another 10 percenthave severe after-effects, including mental retardation.

Incidence of the virus in wildlife may be as important an issue as incidence among humans. This is not only because wildlife may be a reservoir that can potentially threaten humans, but because diseases introduced in wildlife have the potential to impact wildlife populations, in this case bird populations, which, in turn, could affect local or regional ecosystems.

The U.S. Geological Survey's (USGS) National Wildlife Health Center and other surveillance agencies have found West Nile in at least 18 species of wild birds ranging from pigeons and bluejays to a mallard duck. Continued monitoring will be essential to detecting risks to both humans and wildlife.

USGS's National Mapping Division works with state and federal agencies to incorporate the epidemiology information on the outbreak with a geographic information system (GIS) for display and analysis.

Return to Menu

Some important public policy issues may warrant media scrutiny and analysis:

• How are local mosquito-control programs funded, and how well-funded are they? Is this funding a federal, state, or local responsibility?
• Is the cure sometimes worse than the disease and is prevention an alternative to remedy an after-the-fact situation through aerial spraying? Authorities said aerial spraying of the pesticide Malathion in New York during 1999 was not only safe but was also justified because of the risk of disease. But some environmentalists question the risks of such broad public exposures.
• How many other "emerging diseases" are popping up on the radar screens of health surveillance authorities (or sneaking under the radar, as West Nile almost did)?
• What work is being done on vaccines for insect-borne viral encephalitis diseases? How well funded is the research, and what priority is it being given?
• What other exotic species are threatening our landscapes, our waters, and our native plants and wildlife?
• What sort of cooperation exists among state and federal agencies working on human, domestic animal, and wildlife health and disease problems?

Return to Menu

Here are some of the major news sources on West Nile Virus:

• U.S. Centers for Disease Control and Prevention. Federal agency responsible for disease surveillance and epidemiological detective work.
• U.S. Geological Survey (USGS) and the USGS National Wildlife Health Center. Federal agency responsible for monitoring the viral infection in wildlife and mapping the infection in humans and wild-life.
• U.S. Environmental Protection Agency. Responsible for pesticide safety.
• City, county, and state health departments. Agencies responsible for collecting reports of diseases and passing them along to CDC, and also for preventing and responding to local disease outbreaks.
• Local and state mosquito control and abatement districts or agencies. Responsible for keeping mosquito populations down.
• State wildlife agencies. May help monitor health of bird populations.
• Local medical research centers or hospitals. May treat actual cases and have experts to interview.

Return to Menu

U.S. Geological Survey, West Nile Virus Resource

CDC http://www.cdc.gov/ncidod/dvbid/westnile/index.htm

EPA http://www.epa.gov/pesticides/citizens/mosquitocontrol.htm

West Nile Virus Response Manual http://www.bioterry.com/west-nile-virus/West Nile CenterAwareness/Education/Prevention

Return to Menu