Japan has lifted its ban on Wisconsin poultry products four months after a routine inspection at a Jefferson County poultry farm determined that some birds had developed antibodies to avian influenza, indicating possible exposure to the disease, reports Journal Sentinel Online.

"All initial and follow-up test results were declared negative in early August after an extensive investigation, but it takes time to work through the proper channels to get an international ban lifted," said Paul McGraw, Wisconsin state veterinarian.

In July, animal health officials at the state Department of Agriculture, Trade & Consumer Protection did extensive testing after the antibody discovery. State veterinarians and inspectors, using livestock premises registration and poultry sales records, tested 111 flocks within a seven-mile radius of the initial property. Follow-up test samples were collected from the same birds two weeks later.

"There was never any risk to public health or food safety and the test results showed no signs of the virus itself," Dr McGraw said.

China and Russia also ordered a ban on Wisconsin poultry as a result of the investigation, according to Journal Sentinel Online. State officials say they are continuing to work with the federal government to get those restrictions lifted.