MONTEREY, Calif. – An outbreak of H5 low pathogenic avian influenza (LPAI) was reported at a commercial duck breeder flock of 9,476 birds in Monterey County, California, the World Organization for Animal Health (OIE) reported.

Partial sequencing determined the virus to low pathogenic, OIE said. There have been no clinical signs of illness or increased mortality on the premises. Low-pathogenic viruses typically cause little or no clinical signs in infected poultry, according to the Animal and Plant Health Inspection Service (APHIS) of the US Dept. of Agriculture. The LPAI virus spreads primarily through direct contact between healthy and infected birds, but can also be spread through indirect contact with contaminated equipment and other materials.

OIE said that APHIS and the California Dept. of Food and Agriculture (CDFA) are conducting an epidemiological investigation. The agencies also implemented enhanced surveillance and testing. Two additional commercial poultry locations associated with the affected premises have been quarantined and sampled for avian influenza virus. Test results are pending, OIE said.

According to APHIS, LPAI does not typically kill birds the way that highly pathogenic avian influenza does, so animal health officials will work with premises owners toward additional control measures beyond culling.