Oklahoma has become the 13th U.S. state to detect H5N1 avian influenza in dairy cattle, as confirmed by the U.S. Department of Agriculture, despite the state reporting that the infection occurred months ago.

The U.S. Department of Agriculture (USDA)’s confirmation highlights a more extensive outbreak than initially recognized, with the virus first identified in dairy cattle in late March. Since then, avian influenza has been detected in over 150 dairy herds nationwide.

This occurrence is part of a widespread H5N1 avian influenza outbreak affecting wild birds, poultry, and various mammalian species globally. Notably, four dairy workers have tested positive for the virus this year. The CDC has stated that the risk to the general public remains low.

In April, an Oklahoma dairy farm collected a positive sample when infection was suspected, according to Lee Benson, spokesperson for the Oklahoma Department of Agriculture, Food, and Forestry. The farm recently submitted stored samples to the USDA for testing upon learning of potential financial assistance for lost milk production due to bird flu.

The USDA has initiated a compensation program covering 90% of lost milk production per cow to encourage farmers to test herds and report infections.

The USDA website reports two positive herds in Oklahoma; however, Benson clarified that the confirmed positive sample originated from a single dairy farm with two separate barns.

The Oklahoma Department of Agriculture believes the USDA received the farm’s samples in the first week of July. The herd has fully recovered, and no additional infections have been reported, according to state authorities.

State veterinarian Rod Hall indicated that Oklahoma has provided protective gear to dairy farmers and requested enhanced safety and security measures. There is no mandatory testing for cows in Oklahoma, per the state agriculture department.