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Two encephalitis patients
Dr. Deborah S. Asnis calls the NYC health department to report two cases of encephalitis in elderly patients at Flushing Hospital in Queens, NY. Both patients had been active and healthy before they fell ill, exhibiting symptoms of fever, headache, and mental confusion. -
Another patient
Assistant Commissioner of the NYC Bureau of Communicable Diseases receives another call from Dr. Asnis reporting another case of encephalitis in an elderly patient. -
A Fourth Case
Layton receive a call from a colleague at the New York Hospital Medical Center of Queens who has seen a fourth case of encephalitis. Fewer than 10 cases of encephalitis are reported in NYC in an average year. -
Start of an Investigation
Layton asked Annie Fine, who worked in bioterrorism preparedness, to help her investigate the cases at both hospitals in Queens. They were unable to talk with the patients, as three were on ventilators and the newly diagnosed patient was delirious. Instead, they talked with family and friend visitors, asking questions like what the patients had been doing the past few weeks. The only thing that the patients had in common was that they had spent time outside. -
CDC
Layton calls the CDC to inform them of the outbreak and to hopefully get advice from some of their disease specialists. -
An Outbreak
Four more cases are identified in Queens and the South Bronx. The total was now 9 cases -
Figuring out the Disease
Fine and Layton started to consult data, and look in medical textbooks for what could be causing encephalitis in the patients. The symptoms weren't typical of more common types of enteroviruses, so they thought that it could be caused by an uncommon enterovirus. -
A Clue
Fine gets a hint from a newspaper article. The articale was about the mosquito borne illness St. Louis Encephalitis (SLE) which occurs mostly in elderly people and can cause mental confusion and muscle weakness. -
More Investigating
Officials head out to Queens to the homes of the patients to search for mosquito breeding sites. They find plenty, especially of the species Culex Pipiens, which is known to carry arboviruses such as SLE. -
Serious Numbers
By the end of the week, 60 people are infected and two have already died. -
Test Results and Birds
Layton receives confirmation from blood tests that the patients were positive for SLE. Mayor Guiliani holds a press conference warning people to protect themselves from mosquitoes during the upcoming labor day weekend. The city decided to spray pesticides to try to kill off the mosquito population. Then, Fine starts to get questions about the many dead birds that have been found around Queens during the past week. -
A Brooklyn Case
A case of is confirmed in Brooklyn, the first one outside of Queens and the South Bronx -
A Third Death
A third patient dies at Flushing Hospital in Queens -
Unsatisfactory Diagnosis
The NYS is unhappy with the diagnosis of SLE, as the PCR tests did not turn up positive and that SLE virus had not been isolated from autopsy samples. Under the electron microscope, bird tissue is found not to have SLE but a different Flavivirus. -
Mystery Solved
Duane Gubler, who specializes in animal vectors, announces that in the samples from the dead birds he found not SLE, but a different virus that comes from Africa called West Nile Virus. He figures out that it was killing the birds because they were "New World" species, meaning they would never have been exposed to the virus in order to build immunity as a species. -
Aftermath and Lessons Learned
There were 62 confirmed cases of WNV out of about 1,000 suspected cases and the outbreak was over by the third week of September. One of the biggest lessons learned is to ignore the old adage "When you hear hoofbests, think horses, not zebras." By looking in unsuspecting places, the detectives in this case were able to solve the problem of WNV.
