Mexican veterinary authorities are confirming this week there has been an outbreak of avian influenza near Guadalajara that has caused the death of nearly a quarter million chickens since early June and so far has forced a quarantine zone around three poultry processing facilities in the Mexican state of Jalisco.

In a follow-up report submitted to the World Organization for Animal Health (OIE), Mexican animal health officials said intravenous pathogenicity tests revealed a highly pathogenic H7N3 subtype that is the cause of the current outbreak. Mexican veterinary authorities are intensifying avian influenza control efforts in the region, which houses several large commercial farms.

The event represents the first highly pathogenic avian influenza outbreaks in Mexican flocks since the country battled H5N2 in the mid 1990s.

The outbreaks began at three large commercial farms in Jalisco state on Jun 13, causing clinical signs in the layer flocks that included gasping, lethargy, fever, and death. The disease sickened 587,160 of more than 1 million susceptible birds, killing nearly 220,000 of them.

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