Nebraska has its first case of tuberculosis in cattle in more than 17 years.

A spokesperson for the state Department of Agriculture said it could take months to investigate the Rock County incident.

The situation could result in restrictions on Nebraska cattle leaving the state, but pasteurization of milk and normal cooking of meat minimize the possibility of passing the disease to humans.

Christin Kamm of the Agriculture Department said the last outbreak of bovine tuberculosis in Nebraska was in the 1990s.

"We've been accredited to be tuberculosis-free for some 17 years," she said.

State officials followed their usual policy of not identifying the producer involved. But they're working with their federal counterparts, and the herd has been placed under quarantine during the testing and investigation phase.

Kamm said Monday it's too early to say if the disease might turn up on other farms in the same area.

David Smith, an extension veterinarian with the University of Nebraska-Lincoln, said Michigan, Minnesota and California are already on the list of states with recently diagnosed tuberculosis cases.

"It's a very serious issue, one that we have a lot of interest in," Smith said.

He said the main concern is public health.

Depending on the outcome of the Nebraska investigation, other states could impose restrictions on Nebraska cattle crossing their borders.

Asked about possible causes, Smith cited "concerns about this being transmitted from people or cattle coming from Mexico. The other one is that there have been wildlife associated with tuberculosis outbreaks," including deer.

The highly contagious disease is often not detected through obvious sickness on the farm.

"You're not looking for sick cattle. You're looking for small lesions that might exist in healthy cattle that have gone to slaughter."

Reach Art Hovey at 473-7223 or ahovey@journalstar.com.