Avian Cholera News

• Photos of Avian Cholera Die-off at Great Salt Lake by Charles Uibel
• Disease felling fowl at lake - Salt Lake Tribune, United States
• Avian cholera killing water fowl at Great Salt Lake - Salt Lake Tribune, United States
• Utah: Cholera Suspected in Bird Deaths - New York Times, United States - Jan 4, 2008
• Birds in Great Salt Lake Felled by Cholera by the Thousands - New York Times

Update: The avian cholera outbreak that recently caused the death of thousands of birds on the Great Salt Lake (GSL) appears to be over. Two mortality events in November and December, about 15 miles apart, affected mainly eared grebes, northern shovelers, California gulls, and green-winged teal. Eared grebes began dying around November 6th near Promontory Point; by December 1, estimates were that about 15,000 grebes out of a flock of 1.5 million died. Further south, near the town of Saltair, another die-off began around December 17 that affected grebes, green-winged teal and northern shovelers. About 1,500 birds died in this area. Avian cholera die-offs on the GSL are fairly common: in 1994, 15,000 birds died; in 1995, 1,000 birds perished; in 1998, 44,000; in 2002, nearly 30,000, and in 2004, again nearly 30,000. The USGS National Wildlife Health Center has been involved with helping Utah wildlife officials investigate many of these disease outbreaks.

Avian Cholera

Most species of birds and mammals can become infected with different strains of Pasteurella multocida; however, avian cholera in wild birds is primarily caused by one strain, Type 1. The species of birds most commonly affected are ducks and geese, coots, gulls, and crows.

The bacteria can be transmitted by bird-to-bird contact, contact with secretions or feces of infected birds, or ingestion of food or water containing the bacteria. Aerosol tranmission may also occur. The bacteria may survive up to 4 months in soil and water.

Clinical Signs/Field Signs
Large die-offs are seen primarily in wild ducks and geese where the disease affects birds peracutely. The sudden appearance of large numbers of dead birds in good body condition with few if any sick birds is observed. Death may be so rapid that birds literally fall out of the sky or die while eating with no previous signs of disease. Sick birds appear lethargic, and when captured may die within minutes. Other signs include convulsions; swimming in circles; throwing the head back between the wings; erratic flight, such as flying upside down or trying to land a foot or more above the water; mucous discharge from the mouth; soiling or matting of the feathers around the vent, eyes, and bill; pasty, fawn-colored or yellow droppings; or blood-stained droppings or nasal discharge.

Lesions
Hemorrhages may be seen on the heart, liver, gizzard, and intestines. Areas of tissue death appear as white or yellow "spots" on the liver and spleen. The liver may appear darkened or copper in color, and may be swollen and rupture when handled. These lesions are indicative of an acute disease process and are not unique to avian cholera infection. The upper digestive tract may contain recently ingested food, while lower digestive tract may contain a thick yellowish viscous fluid that contains large numbers of P. multocida bacteria.

Wildlife Management Significance
Avian cholera is highly contagious and can spread rapidly. Prompt action is needed to prevent and minimize the spread of the disease. Careful carcass collection and disposal helps reduce the amount of bacteria in the environment. Recommendations are site specific. Contact the National Wildlife Health Center for more information.

For additional information on this or any other wildlife health topic, contact the National Wildlife Health Center at (608)270-2400.