Darwin Chronicles

December 2005

Mule deer buck tests positive for chronic wasting in Colorado

A mule deer buck taken by a hunter in game management unit 102 has tested positive for chronic wasting disease (CWD), according to the Colorado Division of Wildlife.

This is the first case of CWD to be found in that area, which is located in southern Yuma County. The deer was taken near the headwaters of Black Wolf Creek.

The hunter submitted tissues from the animal to the department as part of its CWD surveillance program. Colorado State University’s Veterinary Diagnostics Laboratory performed the initial and secondary testing.

“Based upon what we know about deer movements out of river bottoms, it isn’t surprising to find a positive deer in this location,” said Mike Trujillo, district wildlife manager for the wildlife division in Yuma. “Previous research has shown some deer move back and forth from the plains to the South Platte River bottom, where about 4% of mule deer have CWD.”

The Division of Wildlife is notifying those who will be hunting in the area about the positive deer. The department is interested in collecting additional samples this month during the late plains rifle season (Dec. 1 to Dec. 14), the whitetail season (Dec. 15 to Dec. 31) and the remaining archery season. Hunters with licenses for these seasons in the areas where the deer was found will also be notified that the CWD testing fee will be waived as an incentive to submit samples.

CWD is a fatal neurological illness of elk, mule deer, white-tailed deer and moose. Animals with CWD have been found in portions of northeastern Colorado and southeastern Wyoming for more than two decades.

Federal and state health officials have found no connection between CWD and human health. As a precaution, they recommend that humans not consume meat from animals that appear ill or test positive for the presence of disease, including CWD. For more information, visit www.wildlife.state.co.us.

Farmers and other animal workers at risk for swine flu, according to study

Farmers, veterinarians and meat processors who routinely come into contact with pigs in their jobs have a markedly increased risk of infection with swine influenza viruses, according to a study done at the University of Iowa.

The strikingly higher risk of infection coupled with the fact that pigs can be infected by swine viruses, avian viruses as well as human flu viruses act as a viral “mixing bowl,” especially on farms where pigs, chickens and people coexist, according to researchers writing in Clinical Infectious Diseases.

The study results suggest that occupational exposure to pigs significantly increases the risk of developing swine influenza infection. Agricultural workers should, therefore, be considered in developing flu pandemic surveillance plans and antiviral and immunization strategies, according to the study’s co-investigator, Gregory C. Gray, MD, director of the University of Iowa Center for Emerging Infectious Diseases.

“If migratory birds introduce the H5N1 bird flu virus into swine or poultry populations in this country, agricultural workers may be at a much greater risk of developing a variant H5N1 and passing it along to nonagricultural workers,” Gray said in a prepared statement. “Not protecting agricultural workers could amplify influenza transmission among humans and domestic animals during a pandemic and cause considerable damage to the swine and poultry industries, as well as the U.S. economy.”

Swine influenza infections generally produce mild or no symptoms in both pigs and humans. However, exposure to swine flu virus at a 1988 Wisconsin county fair resulted in serious illness in 50 swine exhibitors and three of their family members; one previously healthy woman who became infected died.

The U.S. swine industry, which employs about 575,000 people, has shifted during the past 60 years from primarily small herds located on family farms to large herds maintained in expansive but confined agricultural facilities. Crowded conditions coupled with the constant introduction of young pigs to existing herds have made swine flu infections among pigs a year-round occurrence rather than the seasonal event they once were.

To determine the prevalence of swine influenza infection among swine-exposed employees, the researchers, led by Gray and graduate student Kendall P. Myers, examined serum samples taken from four adult populations in Iowa between 2002 and 2004. Three populations were occupational groups exposed to pigs: 111 farmers, 97 meat-processing workers and 65 veterinarians. The fourth control group included 79 volunteers from the University of Iowa with no occupational pig exposure.

The researchers tested the serum samples for antibodies to several swine and human influenza A viruses that were circulating during the study. The results showed that all three occupational study groups had markedly elevated antibodies to swine flu viruses compared with the control group.

Farmers had the strongest indication of exposure to swine flu viruses, as much as 35 times higher than the control group. Similarly, comparable values were as much as 18 times higher for veterinarians and as much as seven times higher for meat processors compared with the control group. In contrast, exposure to human flu virus in the occupational groups was not significantly different than that of the control group.

Because pigs are susceptible to human infections, both the pork industry and swine workers could benefit from the establishment of a human influenza vaccination program. There is no human vaccine against swine influenza at this time.

Bill cites need for more veterinarians working in public health

Congress is looking at a bill that it hopes will expand the workforce of veterinarians engaged in public health services, citing concern over emerging animal-borne diseases, such as avian influenza.

The bill, known as the Veterinary Workforce Expansion Act, would provide $1.5 billion over the next 10 years to expand the size of veterinary schools and increase the number of veterinarians trained in public health and biomedical research.

“As animal-borne diseases, like avian flu and mad cow, are approaching our borders, our government is facing a severe shortage of veterinarians,” said U.S. Rep. Jan Schakowsky (D-Ill.) in a release. “The Veterinary Workforce Expansion Act would ensure that our public health is protected by expanding educational programs in veterinary medicine and providing incentives to encourage more students to become vets.”

The bill, H.R. 2206, was introduced in May by U.S. Rep. Charles “Chip” Pickering (R-Miss.) and has received bipartisan support from 15 co-sponsors, including Schakowsky. Sen. Wayne Allard (R-Colo.), a veterinarian, introduced a companion bill in the Senate.