While you are likely seeing numerous articles on a new wave of highly pathogenic avian influenza (HPAI) in the US, there is a great deal of misinformation being reported in both the media and social media. To offset this, TAG compiled a set of HPAI FAQs providing scientific information and related sources on both the public health and food safety aspects of HPAI. Following, based on the FAQs, is a discussion on HPAI food industry effects, food safety impacts and TAG recommendations.
The currently circulating virus, H5N1, is highly pathogenic, but it is not well adapted to infect mammals nor does it show influenza antiviral resistance, so CDC sees health risks to humans as low and existing vaccines for animals as effective. Although the current strain has affected more than 1,000 poultry flocks (82 million birds) across 48 states since being detected in January 2022, of the more than 360 million egg-laying chickens currently in the US, fewer than 4 million (1%) were estimated to be affected as of April 2024. However, in late March 2024, HPAI was detected in dairy cattle in Florida and Texas, likely transmitted from wild birds. As of this writing, confirmed positive dairy herds have been found in Idaho, Michigan, Kansas, New Mexico, and Texas, with additional presumptive positives in Idaho, Texas, and Ohio.
When about 5% of the cattle on a Texas farm showed symptoms (e.g., drop in milk production, decreased appetite and rumination, mild respiratory signs, low-grade fever, thickened “colostrum-like” milk), HPAI was detected in about 95% of the raw milk samples collected, with significantly lower detection in nasal (20%) and fecal (10%) samples. Although the transmission routes to cattle are as yet unknown, researchers suspect that the virus replicates well in mammary tissue, as the high rate of the detection in raw milk would attest.
Despite the detection of HPAI in the raw milk, FDA has stated that there is no risk in drinking pasteurized milk, because the pasteurization inactivates the virus when present. Additionally, when provided with proper veterinary care, infected cows recover in a couple of weeks, and there is no current indication that HPAI is in the beef supply chain. Because of this, milk availability is not expected to be impacted, because sick cattle represent a very limited part of the overall supply of milk. On the other hand, egg availability can be impacted by widespread HPAI in poultry, however eggs from infected poultry are unlikely to be in the retail market, because the rapid onset of symptoms in poultry means that these birds are removed from farms.
To help decrease the risk of HPAI spread, all farms should take preventive measures, implementing sound biosecurity measures, such as limiting the moving of cattle, proper care and cleaning of mammary tissues, cleaning and disinfection of milking equipment, and excluding wildlife and domestic animals from buildings. Additionally, dairy cattle health should be monitored, with any sick animals separated from the rest of the herd and their milk discarded, following guidance from state regulatory officials.
Although one dairy farm worker did test positive and had mild HPAI symptoms (conjunctivitis), there is no evidence that the H5N1 viral genome will become more transmissible to humans. However, CDC has recommended preventive action for those who could potentially have direct or close contact with sick or dead animals, or their fecal material, litter, or other potentially contaminated items. Workers are advised to be trained on, and use, PPE (e.g., goggles, gloves, boot covers, respirator/N95 mask, coveralls, and hair coverings) and avoid eating or drinking in potentially contaminated areas. All dairy workers should be monitored for respiratory symptoms and eye redness; and only pasteurized milk should be fed to other cows/calves or consumed by humans.
If you have concerns about avian influenza or the infection of your animals or workers, give TAG a call. Our experts can help.
Following is a link to the full set of HPAI FAQs and their sources, along with other resources for additional information on HPAI, H5N1, and the evolving situation:
