#19,405
Since last Monday, Washington State has reported 3 more infected dairy herds (2 in Yakima County, 1 in Benton), bringing to 43 the number of herds reported since the first week of October.
The number of human infections remains at 3 (1 fatal), with the CDC posting the following brief description in yesterday's FluView.
Novel Influenza A Virus Infections
Two confirmed human infections with avian influenza A(H5) virus were reported to CDC this week, including one death. To date, human-to-human transmission of avian influenza A(H5) virus has not been identified in the United States.
Both cases were reported by the Washington State Department of Health and occurred in adults aged ≥18 years who worked at commercial dairy cattle farms where highly pathogenic avian influenza (HPAI) A(H5N1) virus has been detected in cows.
One individual developed respiratory symptoms during the week ending October 24, 2026 (Week 42). The patient presented to an emergency department the following week, was hospitalized, and has died. A respiratory specimen collected at the healthcare facility tested positive for influenza A and was presumptive positive for influenza A(H5) at the University of Washington. The specimen was sent to the Washington State Public Health Laboratory where influenza A(H5) was confirmed using the CDC influenza A(H5) assay. Additional testing conducted by the University of Washington determined this was an avian influenza A(H5N1) virus.
The second individual developed conjunctivitis and sought healthcare. Specimens were collected from the individual and tested at the state public health laboratory using the CDC influenza A(H5) assay during the week ending October 31, 2026 (Week 43). Influenza A(H5) virus was confirmed by the state public health laboratory. The specimen has been shipped to CDC for additional testing.
There has been a total of three influenza A(H5) cases in dairy workers in Washington.
The USDA continues to report a sharp uptick in backyard and commercial poultry outbreaks of HPAI H5 across the nation, with 18 states reporting spillovers. California is currently hardest hit, with > 1,300,000 birds affected.
Canada has reported 27 outbreaks since bird flu activity resumed in mid-September, with 6 reports filed over the past week.
And lastly, Mexico's Senasica is reporting a large outbreak of H5N1 in Yucatán. While Mexico has reported H5N1 in wild birds recently, this appears to be the first poultry outbreak since 2024.
(Translation)Agriculture promptly addresses avian influenza case in Yucatán
Senasica is conducting a diagnostic assessment to determine if there are more affected farms and will analyze the appropriateness of authorizing emergency vaccination.
National Service for Agrifood Health, Safety and Quality | November 5, 2026 | Press Release
The Ministry of Agriculture emphasizes that the consumption of eggs and chicken is completely safe and that there is no risk to the national poultry industry.
In a timely response of less than 24 hours, the Ministry of Agriculture and Rural Development (Agriculture) confirmed and activated international health protocols for the control of a case of highly pathogenic avian influenza (HPAI) AH5N1, detected in a commercial Poultry Production Unit (UPA) for table eggs in Umán, Yucatán.
The affected farm had a population of 225,860 laying hens, a figure that represents only 0.09 percent of the national inventory, so the event does not impact the supply in the market.
The Ministry of Agriculture reiterates to the public that this case does not pose a risk to the national poultry industry. The supply of poultry products nationwide is fully guaranteed, and the consumption of poultry meat and eggs is completely safe.
Upon receiving notification of the unusual mortality of 862 birds from the farm's veterinarian, official personnel from the National Service for Agrifood Health, Safety and Quality (Senasica) immediately went to the site. Following strict biosecurity protocols, samples were taken and tested positive for HPAI subtype H5 at the Official Biosafety Level 2 Laboratory in Mérida.
Subsequently, the samples were transferred to the Biosafety Level 3 Laboratory of the Mexico-United States Commission for the Prevention of Foot-and-Mouth Disease and Other Exotic Animal Diseases (CPA) in Palo Alto, Mexico City, for further virus isolation and sequencing tests.
Therefore, he stated that specialists from CPA-Senasica delimited a risk area of 10 kilometers in radius and immediately implemented international counter-epidemic measures:
- A definitive quarantine was applied to the UPA and the total depopulation of the farm was carried out, sanitary disposal of the birds, destruction of waste and contaminated materials, as well as the cleaning and disinfection of the facilities.
- After the sanitary break period is completed, sentinel birds will be introduced to verify the absence of the virus before authorizing restocking.
- CPA technicians deploy sampling in all fattening, commercial egg-laying and breeding UPAs located within the risk perimeter.
The diagnosis will determine if there are more affected farms and, according to the results, the General Directorate of Animal Health of Senasica will analyze the appropriateness of authorizing emergency vaccination of the birds that are in the farms surrounding the detected case.
As part of the origin analysis, authorities also inspect nearby bodies of water, where migratory wild birds from the north of the continent usually arrive during the winter season.
In addition, he reported that an expert group in wildlife epidemiological surveillance will soon arrive to intentionally and systematically search for cases of the disease in free-living birds and thereby confirm whether the source of infection is associated with infected migratory species.
During the winter season, the Ministry of Agriculture intensifies epidemiological surveillance throughout the country and invites producers to reinforce biosecurity measures on their farms and to report any suspicion immediately through the Senasica service channels: telephone line 800 751 2100, WhatsApp 55 3996 4462 and email gestioncpa.dgsa@senasica.gob.mx .
