Wildlife Disease News Digest

Gene Mutation Turned West Nile Virus into Killer Disease
Environment News Service - ens-newswire.com
20 Aug 2007
Photo courtesy of NWHC

A gene mutation that appears to be responsible for changing relatively mild forms of the West Nile virus into a highly virulent and deadly disease in American crows has been identified by U.S. government and university scientists. Because it is susceptible to the West Nile virus, the American crow has served as the major sentinel species, playing an important role in alerting scientists and health professionals to the movement of the disease across North America. Studies have found that deaths of American crows due to West Nile virus are associated with higher rates of infection among mosquito populations and clusters of the disease in humans. This year to date 444 people have been stricken with West Nile virus, and 15 of them have died.

"The findings from this study highlight the potential for viruses like West Nile to rapidly adapt to changing environments when introduced to new geographic regions," said Aaron Brault, a virologist at the Center for Vectorborne Diseases in the Department of Pathology, Microbiology and Immunology of the University of California-Davis School of Veterinary Medicine. "The study also suggests that the genetic mutations that create such adaptive changes may result in viral strains that have unexpected symptoms and patterns of transmission," Brault said. West Nile virus, which is passed back and forth between birds and mosquitoes and transmitted to humans via mosquito bites, was first identified in 1937 in Uganda.

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Avian Influenza, Poultry vs Migratory Birds - Archive Number 20070820.2719
ProMED-mail - promedmail.org
20 Aug 2007

"The claim that migratory birds are responsible for the long-distance spread of highly pathogenic avian influenza viruses of subtype H5N1 rests on the assumption that infected wild birds can remain asymptomatic and migrate long distances unhampered. We critically assess this claim from the perspective of ecologic immunology, a research field that analyzes immune function in an ecologic, physiologic, and evolutionary context. Long-distance migration is one of the most demanding activities in the animal world.

We show that several studies demonstrate that such prolonged, intense exercise leads to immunosuppression and that migratory performance is negatively affected by infections. These findings make it unlikely that wild birds can spread the virus along established long-distance migration pathways. However, infected, symptomatic wild birds may act as vectors over shorter distances, as appears to have occurred in Europe in early 2006."

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USDA Distributing Oral Rabies Vaccine in New York, Pennsylvania [Press Release]
USDA (Posted by thehorse.com)
20 Aug 2007
Photo courtesy of APHIS
Area: New York, Pennsylvania USA

The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) will distribute oral rabies vaccine baits in August to prevent the spread of raccoon rabies in portions of southwestern New York and western Pennsylvania. In cooperation with state departments of agriculture, health and key agencies, baits containing oral rabies vaccine will be distributed over rural areas using low-flying twin-engine aircraft. Hand baiting will occur in populated regions using ground-based vehicles. The projected two-week program will target raccoons and distribute approximately 1.4 million baits covering roughly 6,400 total square miles in two states.

Since 1997, APHIS has been working to establish a rabies-free barrier in the eastern United States where the raccoon variant of rabies threatens wildlife populations and pets, as well as public health and safety. APHIS has coordinated a cooperative effort in the following states: Alabama, Florida, Georgia, Maine, Maryland, Massachusetts, New Hampshire, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Vermont, Virginia, and West Virginia. Baits are coated with a fishmeal attractant and might be packaged in one-inch square cubes or two-inch plastic sachets. Humans and pets cannot get rabies from coming into contact with the baits but are asked to leave the baits undisturbed should they encounter them.

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