West Nile Virus Overview

West Nile Virus Update

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December 8, 2000 - the weekly update maps will no longer be produced.

October 26, 2000 The Mosquito

"The best prevention for West Nile an aviculturist can do is to be knowledgeable about mosquito breeding habitats. And to know that these habitats can range in size from a large swamp to an upturned bottle cap. It does not take much water to make a mosquito."

-- Dr. Lisa M. Reed

Dr. Reed has a background in Ornithology, Behavioral Ecology and Evolution. She developed and maintains the web site that contains the New Jersey Mosquitos - Biology and Control pages. In 1998, Dr. Reed was honored with a Jesse B. Leslie award by the Associated Executives of Mosquito Control Work in New Jersey. A continuously updated list of all known infected species in the U.S. can also be found on the site.

The Bird Lab at Rutgers Department of Entomology is where Dr. Reed and Dr. Wayne Crans are working on three projects involving West Nile virus and Eastern Equine Encephalitis:

Looking at outbreaks based on mosquito populations levels predicted by climatologic models,

Monitoring avian populations in an attempt to understand the role of juvenile birds in the amplification of the virus, and

Establishing the extent of West Nile virus in the wild bird population in New Jersey.

Dr. Reed suggests that, as aviculturists, we study the links listed to the left: Larval Habitats and Mosquito Control Methods - Integrated Pest Management.

October 25, 2000 The Virus is Spreading

Reuters news service reported that the West Nile virus can be passed from bird to bird, as well as through the mosquito vector. The West Nile virus was first reported in the western hemisphere in 1999. Eight people in the U.S. have died from the virus since spring 1999. It was recognized in September of 1999 that the disease, which causes West Nile encephalitis, had spread to 18 bird species, beginning with the crow. Ten species of mosquito in four genera are now known to carry the virus.

The October 25 report stated that the virus transmission experiment involved housing together crows known to be infected and healthy crows. The infected crows died in five to eight days and the previously uninfected crows died five to eight days after the first crow had died. This test, performed by the U.S. Geological Survey's Wildlife Health Center in Madison, Wisconsin, gave the first evidence that the disease could be contracted by means other than through the bite of a mosquito.

Dr. Robert G. McLean holds a Ph.D. from Penn State and has 30 years experience in wildlife diseases. He is the Director of the USGS, which has been studying and tracking the disease in conjunction with the Centers for Disease Control and Prevention (CDC) in Fort Collins, Colorado, and the U.S. Dept. of Agriculture (USDA), as well as with regional public health and natural resource agencies.

In December, 1999, Dr. McLean testified before a Congressional field hearing on the West Nile virus. At the time, he had reported that the distribution of the virus was limited to New York, New Jersey and Connecticut. This year the disease has been tracked to 11 states and the District of Columbia, as far north as Vermont and as far south as North Carolina, where a dead crow was found to have had the disease last week. A total of 15 states are tracking and collecting specimens. Crows are particularly important as sentinels because they are highly suseptible to the virus and they generally do not travel over 200 miles.

The virus is still being considered a disease of birds and mosquitos, but, although last year's outbreak included only a few species of birds plus horses and people, this year's outbreak has been of a very different nature. According to USGS figures, avian mortality has now reached 63 species, including 53 free-ranging species.

The West Nile virus was first detected this calendar year in New York and New Jersey in May. It has now been found in 19 species of wild mammals including bat, squirrel, raccoon, chipmunk and skunk. Domestic animals have included chickens, rabbit, cats, macaw, cockatoo and parakeet. An escaped cockatiel was also reported to have died from the disease in September. On October 17, 2000, the USDA Animal and Plant Health Inspection Service reported documentation of over 3,600 avian mortalities this calendar year.

McLean has also noted that "The high mortality in crows and other bird species ... suggests that this virus is more virulent to our native birds, or it may represent a new, more virulent strain of the virus [than the virus found in Africa and the Middle East]."

-LS 82000

This article may be reprinted freely as long as titles and copyright remain.

Figures were compiled from several sources.