Staten Island is a West Nile hot zone. ŠNYCDOH   September 21 Overnight, USAMRIID confirmed that a flavivirus had killed the birds. September 22 The human toll went up to nine deaths, with an additional nine cases reported. The virus was detected in a dead crow, and in mosquitoes trapped at a country club in suburban Greenwich Connecticut. Officials immediately restricted outdoor activities from 5:00p.m. to dawn, when mosquitoes are most active, and began preparing for widespread aerial spraying of an insecticide called Scourge. They explained that the risk of actual infection from mosquitoes is very small, and urged people to stay calm. The CDC's Division of Vector-Borne Infectious Diseases found that samples received from the National Veterinary Services Lab test positive for a flavivirus. September 23 Scientists at the Army lab called McNamara to report that the bird samples tested weakly positive for SLE and that they were pursuing other possibilities. The CDC called McNamara to request more tissue samples, and began testing for a wider range of diseases: West Nile, Japanese encephalititis, Powassan, dengue, and yellow fever. A University of California researcher narrowed down the viruses in the human brain tissue to one of two flaviviruses, Junjin or West Nile. September 24 USAMRIID reported that the samples "really lit up" when they were tested for a mosquito-borne virus called West Nile. Very similar to SLE, this disease has rarely been seen outside Africa, Australia, and the Middle East. That same day, with help from all of the labs involved, the CDC came to the same conclusion. They suspected that humans had been infected by the same virus. "It was a total surprise to us," said Dr. Duane Gubler of the CDC. "There was no reason to suspect that we'd find West Nile here. An announcement was briefly postponed until genome sequencing was completed and human diagnoses confirmed. The University of California researcher confirmed that he had detected West Nile in the human tissue. September 25 Government scientists reported that the mosquito-borne illness might not be SLE but West Nile virus (WNV). Medically speaking, the announcement was insignificant: the symptoms and treatment are the same. If anything, WNV is slightly less virulent. But from an epidemiological point of view, the news was remarkable. West Nile virus had never before been found in the Western hemisphere, in birds or people. It had occasionally made its way to Europe, most recently to Romania in 1996, when 90,000 cases were confirmed and 17 people died. To pin down the source of the disease the CDC began large-scale testing of people with symptomsa and trapped mosquitoes and birds. City officials set up special help lines and asked residents to call in sightings of dead birds. Upon examination, blood samples from healthy birds showed evidence of West Nile virus-neutralizing antibodies. September 26 Two dead crows found in southeast Pennsylvania tested positive. Although these are the first confirmed findings of WNV in the state, officials are not surprised that the virus has traveled this far. September 27 A 73-year-old woman from Queens tested positive for WNV, along with two more New Jersey residents. A 72-year-old woman from Bayonne was recovering, but the virus claimed the life of an 82-year-old man from Little Falls. He became ill September 3 and died on September 14. September 28 The CDC and international scientists found a link between the NYC strain of West Nile and a recent strain from Israel. September 30 West Nile Virus was isolated from Culex mosquitoes collected in Queens. October 2 The director of the U.S. Geological Survey (USGS) National Wildlife Center reported that the virus has now been detected in more than 63 species of birds, including 53 free-ranging species from eight states. This will enable the virus to travel much farther south and west. In addition to humans, other mammals that have tested positive include horses, three species of bats, a raccoon, and the eastern chipmunk. The number of mosquito species carrying the virus jumped from one to eight. October 3 The sixth human death from West Nile was reported. October 5 Birds from New Jersey tested positive. October 16 The death of two Long Island horses from West Nile was confirmed. October 20 The West Nile virus was found in a dead crow in North Carolina, about 40 miles southwest of Raleigh. This is the farthest south the virus has been found. October 26 A laboratory experiment showed that the virus could travel from bird to bird. Healthy, or "control" crows were confined with infected crows in an enclosure where they shared food, water, and perches. The control birds died five to eight days after the infected crows, and infected a fifth control bird that died eleven days later. Until then, it was thought that the virus was transmitted only through mosquito bites. "The setting was a very controlled scientific experiment and we're not sure if or how this relates to what is happening in the wild," said Dr. Robert McLean, director of the USGS National Wildlife Health Center. "But this certainly opens up a host of new questions." October 28 A crow that died of West Nile was collected in Baltimore, MD. Temperatures dropped, bringing an end to mosquito activity for the year. November 8-9 The Center for Disease Control hosted a conference to develop short- and long-term guidelines for monitoring and coping with West Nile virus--and any other mosquito-transmitted viruses--in the United States. Like many cities, New York City did not have a mosquito-surveillance plan in place, and insects are not routinely monitored unless a specific disease is being investigated. Even when public health researchers aren't sure exactly what to look for, surveillance can alert them to the appearance of new mosquito species (which could transmit other diseases), or alert them to bird illnesses. The CDC dedicated $2.5 million to detect and prevent a possible West Nile outbreak in the following year.      3 of 4