Highly pathogenic avian influenza (HPAI) has reappeared in Mexico.

Two outbreaks of H7N3 avian influenza were identified in the country, according to information sent last week by the National Health, Food Safety and Quality Service (Senasica) of Mexico to the World Organisation for Animal Health (OIE). Two outbreaks from last year have been resolved.

Of the four reported outbreaks, one in Tehuacan, Puebla (in commercial laying hens), and San Ignacio Cerro Gordo, Jalisco (in backyard birds), were resolved before October 2015, according to the details of the epidemiological monitoring.

The third focus mentioned in the OIE report, derived from the active surveillance nationwide, was identified January 26 in a flock of laying hens at a farm in Lagos de Moreno, Jalisco, with viral isolation positive for HPAI subtype H7N3.

The birds do not show signs suggestive of avian influenza, perhaps because they were within a vaccination program. To confirm the diagnosis, an intravenous cerebral index (IVPI) analysis was carried out and a 2.85 titre was obtained. The farm has been quarantined and the epidemiological investigation and diagnosis of situation in the perifocal area has been started.

So far, five more positive viral isolates in farms located in the Encarnacion de Diaz county have been identified. All farms belong to the same company of the index focus. The Senasica lab is expected to provide confirmation diagnoses.

On the other hand, according to a producer report, February 15 a positive viral isolation HPAI subtype H7N3 and IVPI of 2.92 was identified in a farm in the town of Tochtepec, Puebla. The farm has been depopulated and the epidemiological investigation and diagnosis of the situation in the perifocal area has begun. It should be noted that this focus is resolved.

More information about these health events will be provided to the OIE as research advances.

Meanwhile, among the measures implemented are the restriction of movement within the country, screening, disinfection of infected premises, quarantine, zoning, prohibition of vaccination and affected animals are not given any treatment. Birds are then slaughtered and carcass by-products and animal waste are disposed.