Credit Wikipedia
Large outbreaks have been fairly rare the past few years, but in 2012-2013 (see OIE: Mexico Reports HPAI H7N3 In Two States), H7N3 forced the culling of more than 22 million birds.
- In December of 2016, at least two veterinarians caring for sick cats at a NYC shelter were mildly infected with H7N2 (see J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016).
- 3 mild cases were reported in Italy in 2013 (see ECDC Update & Assessment: Human Infection By Avian H7N7 In Italy).
- Mexico reported a couple of mild human H7N3 infections back in 2012 (see MMWR: Mild H7N3 Infections In Two Poultry Workers - Jalisco, Mexico), resulting in conjunctivitis without fever or respiratory symptoms.
Most of the outbreaks of H7N3 in Mexico have been reported from the central and southern states, but yesterday Mexico's SENASICA (National Health Service, Food Safety and Food Quality) announced two new outbreaks of HPAI H7N3 in Mexico's northern Coahuila State, which borders the state of Texas (although the outbreak is roughly 170 miles from the border).
Agriculture detects the presence of Avian Influenza AH7N3 in two commercial poultry production buildings in Coahuila
The Ministry of Agriculture and Rural Development activated the emergency operation and immediately sent official personnel to take samples that were sent to the official laboratories of the National Service for Agri-Food Health, Safety and Quality (Senasica), located in Palo Alto, City of Mexico
The impact of this event is 0.003 percent of production, so it does not represent a risk for the national supply of food.
Through epidemiological surveillance actions, which it permanently carries out, the National Service for Agrifood Health, Safety and Quality (Senasica) confirmed the presence of Highly Pathogenic Avian Influenza AH7N3 (HPAI) in two commercial poultry production buildings from Coahuila.
The agency of the Ministry of Agriculture and Rural Development reported that laboratory tests carried out by technicians from the United States-Mexico Commission for the Prevention of Foot-and-Mouth Disease and Other Exotic Animal Diseases (CPA) confirmed that the outbreak corresponds to the existing strain in some regions of Mexico since 2012.
The technicians of the General Directorate of Animal Health quickly applied the necessary anti-epidemic measures to deactivate the outbreak as soon as possible, quarantined the affected farm and ordered the immediate slaughter of 70,000 birds from the two ships that had positive cases, located in the municipality. General Cepeda, Coahuila.
Senasica received the report of clinical suspicion of avian influenza on Thursday afternoon, immediately launched the emergency and prevention operation to contain the outbreak, for which it sent technicians to the area to take samples in the commercial production units and of family poultry farms located within a radius of five kilometers around the affected farm, with the purpose of measuring the dimension of the outbreak.
Early Friday morning, the PCR tests applied in the Senasica laboratories revealed the presence of Avian Influenza AH7N3 and at this time work is being done on viral isolation for definitive confirmation and proceeding to make the corresponding reports to the World Organization for Animal Health ( OIE, for its acronym in French) and to trading partners.
Among the measures adopted by Senasica, the immediate start of a vaccination campaign for birds located on family and commercial farms in neighboring communities stands out.
He also issued the instruction to reinforce the supervision tasks at the Verification and Inspection Points (PVI) located in Coahuila, in order to prevent the movement of live birds, their products and by-products without official control.
Faced with the contingency, Senasica authorities, in coordination with the Rural Development Secretariat of the Government of the state of Coahuila, summoned the region's poultry farmers to an urgent meeting for tomorrow, Sunday, April 24, with the purpose of reviewing the results of the sampling carried out. by the CPA experts and agree on an action plan aimed at preventing the spread of the outbreak.
A little over 2 years ago the USDA/APHIS Confirmed HPAI H7N3 In South Carolina Turkey Flock, although the OIE later determined it was not related to the Mexican HPAI H7N3 lineage.
In 2017, the USDA Identified Tennessee Bird Flu Virus as HPAI H7N9, while in 2016 an HPAI H7N8 in an Indiana Commercial Turkey Farm, neither of which were linked to the H7N3 virus in Mexico.
Instead, these outbreaks appeared to be due to LPAI-to-HPAI mutation (see graphic below), a reminder that avian flu viruses continue to evolve, both in poultry, and in the wild.
In 2019, we looked at a study (see PLoS One: Rapid Evolution of Mexican H7N3 HPAI Viruses In Poultry), that tracked the evolution and diversification of avian H7N3 in Mexico since 2012, producing at least three genetically distinct clusters of viruses.
The authors speculate these changes may have been driven by a number of factors, including host adaptations while carried by poultry in a confined space, and potentially, vaccine driven escape mutations.
While HPAI H5 remains our primary avian flu concern, there's little to prevent HPAI H7 from joining the fray as migratory birds make their way north to their summer roosting areas.
Stay tuned.
