According to recent reports circulated by the World Organization for Animal Health, highly pathogenic avian influenza, H5N1 strain, has been confirmed in 17 commercial flocks in Mexico as of mid-December.  Fifteen of the cases have impacted commercial laying hens.  States affected included Jalisco, previously recording extensive mortality from avian influenza, H7N3 in 2012.  Five of the commercial laying flocks in the State affected a total of 1.7 hens.  In the state of Yucatan, 1.8 million hens have been infected.  Sonora has also experienced cases with 240,000 birds exposed to the virus.  A commercial laying breeding farm in the state of Sonora with 135,000 hens has been depleted as a control measure.

Backyard flocks in three states have reported mortality but it is evident that recognition of outbreaks and confirmation of diagnoses is limited by available resources.

It is understood that vaccines are now deployed under controlled conditions to limit the incidence rate. Following outbreaks of avian influenza from 2012 onwards, Mexico deployed inactivated oil emulsion vaccines over a wide range of poultry to create an immune population of commercial chickens. This limited dissemination of virus and over time suppressed incident cases below the outbreak threshold but not to the level of eradication.

It is reiterated that it is impossible to eradicate an endemic disease by successive depletion of infected flocks and imposition of quarantines given the periodic introduction of virus by migratory waterfowl and possibly circulation within populations of domestic free-living birds.

In the Western hemisphere during 2022, Canada, the U.S. Mexico, Panama, Peru, Ecuador and Chile have recorded outbreaks of H5N1 highly pathogenic avian influenza in either free-living migratory birds or in backyard and commercial flocks or their combination.