Posted: 08.31.2010
Double-crested cormorants on two islands off the Door County peninsula have tested positive for a virulent form of Newcastle disease, prompting animal health officials to caution poultry farmers to step up their vigilance.
There is no human health threat from Newcastle disease, caused by a virus that infects only birds. The disease was found during routine testing of dead birds found on Pilot Island and Spider Island by natural resources agencies. Confirmation came to State Veterinarian Dr. Robert Ehlenfeldt Wednesday, Aug. 25, from the National Wildlife Health Center in Madison.
A non-pathogenic form of the disease – one that does not sicken the birds – is common in cormorants. But the strain detected in this case was pathogenic, a more virulent form.
“The virulent form of Newcastle disease can be transmitted to domestic poultry, creating hardship for those producers, and probably causing other nations to close their doors to poultry and poultry products from the United States,” Ehlenfeldt said. “While previous outbreaks in the United States have spread to domestic poultry only once, we do want poultry owners to be aware of the potential.”
Cormorants from Door County will begin migrating soon, following the western shore of Lake Michigan and possibly exposing wild and domestic birds to the virus. The department is sending information to Door County and other eastern Wisconsin poultry owners on the state’s livestock premises registration list. In three previous Wisconsin outbreaks, including one in 2006 on Pilot Island, the disease did not spread to domestic poultry.
Symptoms of Newcastle disease include respiratory problems such as sneezing, gasping, coughing and nasal discharge; diarrhea; low energy and loss of appetite; drop in egg production or misshapen and soft-shelled eggs; nervous system impairment such as trembling, drooping wings, circling, and twisting or paralysis of the head and neck; swelling around the head; and purple discoloration of the wattles, combs and legs.
Poultry owners who see any of these signs should call their veterinarian immediately. Anyone who finds dead cormorants should call the Wisconsin Deadbird Hotline, 1-800-433-1610.
The cormorants also tested positive for botulism, a toxin produced by bacteria and common in wild birds under certain environmental conditions. It’s unclear which disease killed the cormorants, but there is not a concern that botulism would pass from cormorants to domestic poultry, because it does not spread between birds.
Ehlenfeldt noted that commercial poultry producers generally practice good biosecurity to protect their birds from disease. He encouraged backyard, hobbyist and other small-scale producers to:
- Keep birds inside if they are at risk of exposure to wild birds
- Restrict vehicular and foot traffic near their birds
- Disinfect shoes, clothing, hands, equipment, and vehicles, particularly after visiting other poultry farms or fairs
- Buy birds only from reputable dealers and ask for certification that birds were legally imported
- Keep new birds separated from the rest of the flock for at least 30 days
- Separate young and old birds, birds of different species, and birds from different sources
- Keep records of all sales and shipments
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