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Bovine TB outbreak polarizes ag community

by Carol Dunn

HUERFANO– Cattle producers in Huerfano County want to relax, but even the remotest chance that bovine tuberculosis (TB) might spread to other herds is too unnerving.  In any given year, a herd of cattle somewhere in the U.S. is found to have an infected animal, with as few as four herds in 2005 and as many as twelve in 2009.  Most producers opt to depopulate the entire herd and start over, sending infected animals to a rendering plant and non-infected animals to slaughter.  Of great curiosity is the fact that Walsenburg’s Corsentino Dairy had not purchased any cattle for six years previous to one of its herd testing positive for TB at a slaughterhouse.  So where did the TB come from?

    TB is still common in less developed countries.  Studies have been conducted to determine, in a country like the United States where human TB is rare and outbreaks in cattle herds are dealt with immediately, how TB can continue to show up from time to time.  In the US, a number of mammals serve as “spillover hosts” when the density of the disease is high.  According to the Iowa State University Center for Food Security and Public Health, those include : sheep, goats, horses, pigs, dogs, cats, ferrets, llamas, deer, elk, foxes, coyotes, opossum, raccoons, lions and some rodents.  TB can also be passed to cattle by infected humans.

    After a California herd tested positive for TB in 2007, the infected animals were traced back to feedlot steers from Mexico.  Two other feedlot cases that year from other states had the same results.  According to Colorado State University Extension, DNA testing of the TB bacteria found in Huerfano County does not match other TB bacteria recorded in the USDA-APHIS database.  Dr. Francisco with APHIS in Ft. Collins told the World Journal she is not permitted to answer media questions to clarify this information, and the only public relations representative available was in the Maryland office and unfamiliar with the Huerfano County case. 

    Besides new animals being moved into the herd, there are few ways that TB is spread among cattle.  One way is nose to nose contact between cattle across fence lines, the risk of which, according to an August 9 news release by Huerfano County Extension, is “very low.”  Other ways include inhaling airborne TB bacteria and consuming feed and water contaminated with saliva from an infected animal.  

    In the Extension press release, Dean Oatman points out that any animals going to the Huerfano County Fair this week from the Corsentino farm have been tested and found negative for TB by state and federal animal health professionals.  The quarantine for these animals has been released by the Colorado State Veterinarian’s Office.  The press release quotes Dr. Keith Roehr, State Veterinarian: “The risk these animals pose to other animals is negligible because they were housed separately, fed separately, cared for separately, and because they have all tested negative for TB.  There is no scientific reason to quarantine these animals or keep them from coming to the county fair.”  County Fair Board member Tracy McCay told the World Journal, “If the State vet released those animals, he must have felt that they were safe.” 

    Oatman also stated that no other herds in the county are under a hold-order or quarantine because of TB, and no other herds in the county have been tested for TB.  The possibility exists that other cattle within the county may be tested.

    Trinidad veterinarian Dr. Kirk Falduto told the World Journal, “Any time you have a communicable disease, there is some degree of concern.”  Falduto said because the animals were confined and not on open range, the outbreak was caught early, and they have a good handle on it, “it’s not a large concern to area ranchers.”  Falduto said there is a latent period for the bacteria where testing could show a false negative, but the State times the testing appropriately.     

    When asked about animals going to the County Fair from the Corsentino farm, Dr. John Davis, Rio Cucharas Veterinary Clinic, told the World Journal, “There is no risk because they tested negative.”  Davis said TB takes a long time to develop in an animal, and it requires “continual exposure for a long period of time” to contract the disease.  Davis referred to TB as “infectious but not highly communicable.”  He said people can live in the same household as someone with TB, and if they practice good sanitation, the chances are small that they will contract it.  “People shouldn’t be preoccupied with this,” he said.  Davis also commended the actions of Brett Corsentino as “extremely responsible” in clearing out his dairy herd, cleaning up and starting fresh.