SPRINGFIELD, Ill. (AP) — The Illinois Department of Agriculture is warning county fair operators to take extra precautions this summer to stop the spread of poultry and livestock diseases.

The agency sent letters to more than 100 county fairs urging biosecurity measures. The letter asks local fair officials to adopt a formal plan on disease response or to update existing plans.

State Veterinarian Mark Ernst says the measures are precautionary. So far no cases of avian flu, which has killed millions of chickens and turkeys nationwide, have been reported in Illinois.

But reports of canine influenza are continuing in northern Illinois, and a horse show in Gifford was cancelled last week after two animals showed symptoms of the equine herpes virus.

Ernst tells The State Journal-Register that there are risks for disease anytime animals are in close confinement and commingled