West Nile virus in zoo birds : clinical, pathologic, and epidemiologic considerations
West Nile Virus (WNV), an Old World flavivirus, was first isolated in 1937, from the blood of a Ugandan woman. It is among the earliest arthropod-borne viruses discovered. WNV was first recorded in the New World with an outbreak occurring in the fall of 1999, when it was detected in birds in New York City and was found to have caused neurologic disease in humans, horses, wild and zoo birds in the northeastern U.S. Despite this surge of interest in 1999, the basic epidemiology of WNV was well documented much earlier, in the mid-1960s, at which time it was confined to Africa, Europe, Asia and the Middle East. Unlike the New World epidemics, with large number of dead and dying birds occurring concurrently with human infection, the Old World epidemics of WNV had few concurrent reports of deaths of infected birds. This difference could reflect both a lack of exposure and adaptation of the virus among New World avian populations. The mode of entry for the new strain of the disease into the U.S. still remains controversial. West Nile virus is a zoonotic flavivirus, classified as an arbovirus, that is closely related to other flaviviruses like SLE (St. Louis Encephalitis), Japanese Encephalitis, Murray Valley encephalitis, and Kunjin. It is an acute, fatal viral encephalomyelitis that is amplified in avian hosts and ornithophilic mosquitoes. Epizootics occur when the virus gains access to mosquito vectors like Culex pipiens, that feed on both birds and mammals. WNV has had an even greater impact on birds than it has on humans. Close to 110 species have been documented as being infected thus far. It has caused substantial die-offs of wild and captive zoo birds since the initial outbreak of 1999. Chief among the species affected are corvids, such as the crow and blue jay, and birds of prey, such as the owl and hawk. Mortality in the American crow is close to 100%. Zoos and captive breeding facilities are very concerned about the potential impact that the disease may have on their avian populations. In response, zoos are now testing all outdoor birds for exposure to WNV. They are also vaccinating birds with an inactivated virus vaccine marketed for horses, the efficacy of which is still unknown. Since August of 1999, there have been seven avian mortalities at the Rosamond Gifford Zoo in Syracuse, New York, which have been confirmed with PCR (on tissues) to be due to WNV. This paper will focus on zoo birds and the diagnostic, treatment, and preventative efforts carried out at the Rosamond Gifford Zoo.
Senior seminar paperSeminar SF610.1 2003 A46
Birds -- Virus diseases -- Case studies