U.S. farm and health officials are racing to assess the threat that a type of bird flu never before seen in the country poses to humans and poultry, employing emergency plans drawn up in the wake of a devastating outbreak in birds last year.

The federal government sprang into action on Friday after confirmation overnight that the virus had hit an Indiana turkey farm, alerting other states to the danger and putting workers who might have been exposed to the virus under surveillance.

Last year's outbreak led to the deaths of more than 48 million chickens and turkeys, either killed by the virus or culled to contain it. No cases were reported in humans.

Strains similar to the new virus, known as H7N8, have on rare occasions made people ill and the U.S. Department of Agriculture (USDA), U.S. Centers for Disease Control and Prevention (CDC) and state officials aim to reduce the risk of human infection.

They also want to blunt the impact on the poultry industry, which suffered billions of dollars in losses in last year's outbreak. Egg supplies shrank and prices surged to record highs.

"We are hopeful that as we respond very quickly to this virus that we can get it contained and hopefully not see an extensive outbreak like we did last year," said T.J. Myers, an associate deputy administrator for the USDA's Animal and Plant Health Inspection Service.

Even if the response is fast, the government's ability to contain the disease is far from certain. Officials have never dealt with this strain before, and wild birds are thought to spread the disease to farms through feces dropped from the air, making infections difficult to prevent.

U.S. officials have taken to heart lessons from last year's outbreak, when USDA workers could not always kill infected flocks fast enough to contain the virus. Workers are now trying to cull sick flocks within 24 hours of diagnoses, following a goal the agency set in the autumn.

Most turkeys at the infected farm were killed within a day, but it was 29 hours before all were dead, said Denise Derrer, spokeswoman for the Indiana State Board of Animal Health.

No human infections associated with the new strain have ever been reported, according to the USDA.