More testing planned; infected animals will be euthanized
By CAROL RYAN DUMAS
State and federal animal health officials have confirmed the detection of bovine tuberculosis in a Tulare County, Calif., dairy herd.
The disease was detected through routine tissue testing at slaughter on the evening of Feb. 7, said Jay Van Rein, a California Department of Food and Agriculture spokesman.
The CDFA veterinarian testing tissue found a suspicious mass and confirmed the disease. State and federal officials have begun testing herds that may have come into contact with the diagnosed cow, which led to the detection of TB in the Tulare County herd.
Officials are working with the owner dairyman and his veterinarian to test animals on the dairy and ensure that biosecurity measures are in place, Van Rein said.
CDFA does not release the name of the slaughter plant or the dairy owner in such cases, he said.
The bulk of the work in the next several weeks will be testing animals at the dairy where TB was detected. Any animal testing positive will be euthanized. Animals can be tested through swabs, but an initial finding of TB typically comes from testing tissue at slaughter because the disease is slow moving and is fairly non-symptomatic, he said.
"Testing tissue gives us a good chance of detecting early and getting ahead of an outbreak," he said.
CDFA and USDA veterinarians are also tracing back any animals that came into contact with the diseased cow and will test cattle on any dairies found to have had contact, he said.
Traceback investigations can take months, as was the case when the disease was detected in a San Bernardino County herd in April, 2011. Tracebacks in that case led to detection on another dairy in October and another in December of that year, and one dairy is still being monitored, he said.
Bovine TB does not threaten the quality and safety of milk and meat products, but cows on a dairy known to have contact with an infected cow must test negative for the disease before their milk can be sold into the food chain, he said.
Detection of the disease can be a major disruption for facilities involved as their milk sales are on hold while testing takes place. But officials are able to get them back in business fairly quickly if other animals are not affected and biosecurity measures are cleared, he said.
The disease is transmitted from cow to cow, is not transmissible to humans and is less contagious than some other diseases. The chance of transmission from humans to cows is minute, but workers are tested as a precaution, he said.
Tuberculosis is a chronic, slow-spreading disease that can remain undetected for years. Infected animals, even those that appear healthy, can spread infection to other animals. California has been involved in TB eradication programs since 1917, according to CDFA.
Almost all milk sold in California is pasteurized to destroy organisms that could be harmful to humans, including TB organisms. The state's raw milk dairies are regularly tested for TB. All cattle processed for meat are inspected for signs of TB infection and rejected if they show signs of the disease, CDFA said in a press release.
To assist in the eradication of bovine tuberculosis, farmers and ranchers should adhere to animal import regulations, require TB testing of new cattle before purchase, maintain permanent identification of animals, keep records of animal movements into and out of their herd, prevent contact of breeding cattle with cattle of unknown origin, and cooperate with government officials on TB investigations.
For more information on the history of bovine TB in California, go to: http://tinyurl.com/av7s3ko