The four farms, located in Buena Vista, Cherokee and Wright counties, have all tested positive for H5 avian influenza following increased mortality.
Additional confirmatory testing is pending from the APHIS National Veterinary Services Laboratories (NVSL) but if the disease is confirmed, all birds on the property will be humanely euthanised to prevent the spread of the disease.
Three of the sites are turkey farms, with the fourth a commercial laying operation. This brings the number of cases of avian influenza to 25 in the state of Iowa.
The Center for Disease Control (CDC) and Iowa Department of Public Health considers the risk to people from these HPAI H5 infections in wild birds, backyard flocks and commercial poultry to be low, while no human infections with the virus have ever been detected and there is no food safety risk for consumers.