West Nile Virus Has Spread to Florida

The West Nile virus has spread to the Southeast for the first time since appearing in New York City in 1999, and the original outbreak of the disease was wider than originally thought, researchers reported Thursday.

Florida and Georgia now have joined other Atlantic Coast states that have seen animals, birds, mosquitoes and humans infected by the virus. The virus can cause meningoencephalitis--inflammations of the brain and spinal cord. Nine people have died of it in the last two years.

The first human infection of 2001 has been identified in Florida, according to researchers at the Atlanta-based Centers for Disease Control and Prevention in this week’s Morbidity and Mortality Weekly Report. In addition, the virus has spread to Georgia through birds. Last year, the spread of the virus via birds was evident only as far south as North Carolina.

“The findings are not entirely unexpected,” said Dr. Stephen M. Ostroff, a CDC medical epidemiologist. “[The virus] spread down the Atlantic Coast during the fall migratory season. What was not predictable was when and where” it would spread.

The virus also could spread westward, he added. As a result, many states monitor for the virus, said Dr. Kathryn Converse, a wildlife disease specialist for the U.S. Geological Survey.

“We have a pretty extensive mosquito-borne surveillance program in California,” said Dr. Curtis Fritz, an epidemiologist in the vector-borne disease section of the California Department of Health Services. The program includes routinely testing chickens that are used as sentinels for the virus and testing mosquitoes, he said. There is also a statewide program for surveillance of dead birds, especially crows, which can be an indication of the virus.

Mosquitoes that carry the virus can infect animals, birds and humans. According to the CDC, humans can only contract the virus if bitten by an infected mosquito.

In related news, researchers from the New York City Department of Health and the CDC reported in The Lancet medical journal that nearly 8,200 people in the New York metropolitan area were infected with the virus during the first outbreak. Many had mild symptoms and did not realize what they had contracted, the research indicates.

The study was conducted in October 1999. The researchers tested blood from people who lived at the epicenter of the outbreak and concluded that about 1,200 people there had the virus. They extrapolated that number to 8,200 for the whole metropolitan area.

For every case of West Nile meningoencephalitis, there were 140 cases of more mild fevers or flus caused by the virus, the research showed. The findings also indicated that “in the very epicenter of the outbreak . . . 70% of the population never used mosquito repellent, even though they were aware of the virus,” said Dr. Farzad Mostashari, a medical epidemiologist in the communicable disease program in the New York City Department of Health and the study’s lead author.

Ostroff said the CDC report is further proof that people should take precautionary steps to protect themselves from mosquito bites and eliminate such common areas for mosquito breeding as clogged gutters, stagnant bird ponds and overturned trash can lids.

He also urged the public to report any dead birds to local and state public health officials.