Eleven more cows have tested positive for bovine tuberculosis (T-B) at a dairy which produced the first T-B infected cow in Washington state in 25 years.

State agriculture veterinarians tested 1,350 at the dairy and say the 11 positive results were lower than expected. Spokesman Hector Castro said these are only initial tests and the 11 cows will be removed from the herd pending further testing. He said in most cases at least one to four percent of the cows in a herd where an infected cow is discovered test positive. A cow from that same dairy tested positive earlier this month at a slaughter house.

Bovine tuberculosis is a highly contagious disease that can easily spread from one cow to another and to people who drink milk from an infected cow. But since pasteurization kills T-B, cases of transmission to humans are extremely rare.

Castro said the infected cow initially came from a dairy in Snohomish County. All the cows at that dairy tested negative. Cows at an operation near the Moses Lake dairy also were also tested and came back T-B free. Castro said there will be more tests over the next several months.

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