THURSDAY, June 13, 2002 (HealthDayNews) -- Three years ago the first cases of West Nile virus spread panic though the New York City area.
Now, government health officials say the new and potentially deadly mosquito-borne pathogen has laid down firm roots throughout much of the United States. It shows no signs of wanting to leave, and every indication that its range will only widen.
Last year, West Nile cropped up in 359 counties across 27 states and the District of Columbia, infecting at least 66 people and claming nine lives, according to a new report from the Centers for Disease Control and Prevention. That's 16 more states -- and more than 2.5 times the number of counties -- than in the previous year.
The virus has now spread as far north as Maine, as far west as Arkansas and as far south as Florida, where it appears to be active year-round instead of during the summer and fall seasons of more variable climates. It has even been detected in Canada and the Caribbean, officials said. Cases in people occurred in 2001 as early as July and as late as February.
"There's really nothing that would limit the ability of the virus to move southward," Dr. Stephen Ostroff, acting director of the CDC's National Center for Infectious Diseases, said at a press conference Thursday about the report.
West Nile is believed to spread from place to place on the wings of infected migrating birds. These birds may also serve as reservoirs of infection for local species. That might help explain why, while birds migrate north to south, the virus has managed to move further west each year since 1999.
Although its symptoms are typically flu-like, the virus can cause a severe brain inflammation, or encephalitis, which in about 14 percent of cases is fatal. The elderly and people with suppressed immune systems are at greatest risk of illness and death. West Nile has no cure.
"At a minimum, human surveillance should include West Nile testing of patients with encephalitis where no other cause can be found. And it should take place well into the fall months since it was noted later in the season in 2001 than in previous years," said Dr. Daniel O'Leary, a CDC epidemiologist who studies the virus.
So far this year officials haven't detected any cases of West Nile in people. Horses are the only mammals besides humans that have been found to contract the disease. But summer is coming and the pathogen will appear. "We have no reason to believe that it will not continue to re-emerge in future seasons," Ostroff said.
Communities that harbor West Nile and the residents of those areas can take steps to reduce its threat, officials said. Mosquito control efforts like spraying with pesticides and the removal of standing water that serves as breeding ground for the insects can reduce their numbers.
Wearing long sleeved shirts and long pants, using bug repellant, and staying indoors during times of peak mosquito activity -- generally early morning and early evening -- can cut the risk of being bitten, and thus infected.
What To Do
For more on West Nile and other emerging infections, try the National Center for Infectious Diseases, the CDC, or the U.S. Department of Agriculture.
