LPAI viruses are commonly found in wild and migratory birds, and often only produce mild symptoms in poultry. The concern is - when LPAI H5 and H7 viruses get into poultry and are not quickly controlled - they have the potential to mutate into highly pathogenic strains.
Hence all H5 & H7 outbreaks are reportable to the OIE, and must be quickly eradicated.Over the past few years we've seen an increasing number of spontaneous LPAI-to-HPAI mutations, both in Europe (see here, here, and here) and in the United States (see here).
While sporadic, Mexico has a long history of both LPAI (low pathogenic) and HPAI (Highly Pathogenic) H5 & H7 outbreaks, going back more than two decades. The last outbreak notified to the OIE was of subclinical H7N3 at a single farm in Jalisco State in April of last year.
Before that, in 2015, Mexico Reported H7 In Chiapas Nature Preserve, Nearby Zoo Closed, followed by more than 2 dozen scattered H7N3 outbreaks (see OIE Followup report #7) across the country between 2015-2016.Large outbreaks have been fairly rare the past few years, but going back to 2012-2013 (see OIE: Mexico Reports HPAI H7N3 In Two States), H7N3 forced the culling of more than 22 million birds.
Beyond the tremendous economic damage to their economy, Mexico also reported a couple of mild human infections with the virus back in 2012 (see MMWR: Mild H7N3 Infections In Two Poultry Workers - Jalisco, Mexico), resulting in conjunctivitis without fever or respiratory symptoms.
Aside from the local impact, this persistence of H7 avian flu in Mexico increases the risk of seeing H7 carried north along the migratory flyways during the spring.While their origins are far from certain, over the past two years the United States has seen limited H7 outbreaks during the winter and spring, with H7N9 reported in 4 Southern states in 2017 and H7N8 appearing at 9 farms in Indiana in 2016.
And just last week LPAI H7 was reported in the Midwest (see CIDRAP's Low-path H7N1 detected at Missouri turkey farm). Whether that presages more to come is unknown, but it is something we'll be watching.All of which brings us to the following (translated) statement from Mexico's SENASICA (National Health Service, Food Safety and Food Quality) website which describes two outbreaks of HPAI H7N3 north of Mexico City, roughly 110 miles apart.
SENASICA reports to the World Organization for Animal Health location and closure of two outbreaks of Avian Influenza AH7N3
To avoid the spread of the virus, two backyard farms were depopulated with a little more than 1,900 birds
This event did not affect the national poultry production This event did not affect the national poultry production
National Service for Agrifood Health, Safety and Quality
March 9, 2018
The National Service for Agrifood Health, Safety and Quality (SENASICA) reported to the World Organization for Animal Health (OIE, for its acronym in French) the finding of high pathogenicity avian influenza virus AH7N3 in a rural and a backyard, which were depopulated immediately to prevent the spread of the virus.
SENASICA ordered the immediate depopulation of the rural property, located in San Felipe, Guanajuato, which had a population of 1,900 birds, so the focus was immediately closed and in the official laboratories the presence of the virus was confirmed.
In the property were located thousand 400 birds of the race Rhode Island and 500 chickens of term posture cycle, it is suspected that the latter infected the rest, because they were vaccinated, which is presumed to come from commercial farms in the area of Los Altos de Jalisco, where there is still circulation of the virus and that through irregular mobilization, were distributed by intermediaries.
Likewise, the virus was identified in a backyard hen in the community of Portezuelos, Cadereyta de Montes, Querétaro; the farm had a population of 26 birds that were also eliminated.
In accordance with the procedures established for this type of findings, the SENASICA technicians carried out the monitoring of farms located in the periphery of 10 kilometers of both foci and no sanitary problems were found.
The findings were the result of active epidemiological surveillance carried out by the agency of the Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA), in order to prevent the spread of the virus and continue with the necessary work to detect its presence in a timely manner.
It is important to mention that the virus was not identified in commercial farms, so this event did not affect the national poultry production, which with more than 200 million laying birds and 300 million broiler chickens per cycle, produce more than six million tons of poultry products.