Any horse coming into Louisiana from Illinois must have a health certificate showing that it has not been at Hawthorne Race Course in the past 30 days because nearly 70 horses at Hawthorne have tested positive for a very contagious and potentially lethal virus, the Louisiana Department of Agriculture and Forestry said Tuesday.

A department news release quoted Stanley Seeling, president of the Louisiana Horseman’s Benevolent and Protective Association, as saying horses typically travel from Hawthorne Race Course to Louisiana for the winter races.

The quarantine is a precaution because at least 68 horses at Hawthorne have tested positive in recent months for equine herpes virus type 1, Agriculture and Forestry Commissioner Mike Strain said.

“This is a highly contagious disease and we will prohibit all horses from Illinois from entering the state unless they are cleared by a veterinarian,” he said.

The virus doesn’t affect people. In horses, it can cause fever, lethargy, abortion, respiratory problems, brain damage and death.

It can be spread directly from horse-to-horse or indirectly through coughing or contact with physical objects contaminated with the virus, such as tack, wipe rags or other grooming equipment, feed and water buckets and people’s hands or clothing.

According to a Dec. 27 news release on Hawthorne’s website, a quarantine on its back stretch could be lifted around Thursday, because Dec. 12 was when the last horse there was moved to quarantine.