West Nile virus epidemic

The accidental contamination of chicken feed with dioxin contaminated fat in Europe shows how food exposure could occur. Because dioxin does not cause immediate symptoms, authorities did not discover the contamination for months in 1999, and Europeans probably consumed the dioxin in chicken meat and eggs sold that year. One lesson learned from this event is that physicians and public health officials need to recognize and report unusual or suspicious health problems in animals as well as humans (1). The 1999 West Nile virus epidemic in birds and humans in New York City reinforced this lesson. Fortunately, biological and chemical contamination of public water supplies will usually pose little risk due to dilution by the large volume of water. 

Biggerstaff BJ, Petersen LR. Estimated risk of West Nile virus transmission through blood transfusion during an epidemic in Queens, New York City. Transfusion 2002 42(8) 1019-26. 

Historically, the four most important arboviral pathogens in the United States were the St. Louis virus, the La Crosse virus, and the eastern and western equine viruses. However, the West Nile virus has been recognized as an emerging pathogen and has been implicated in an epidemic occurring in the United States since 1999. Transmission of these viruses occurs through the bites of mosquitoes. Typically, an incubation period of 2 to 14 days precedes the onset of clinical... 

CDC. Epidemic/Epizootic West Nile Virus in the United States Guidelines for Surveillance, Prevention, and Control. Atlanta, National Center for Infectious Diseases, Division of Vector-Borne Infectious Diseases, 2003. 

---