Credit USDA
#17,981
Although New Mexico has been mentioned now for at least a week as having HPAI presumptive positive cattle, the verification process by the National Veterinary Services Laboratories (NVSL) - which is undoubtedly dealing with a large number of samples - can take some time.Late yesterday (April 1st) the USDA reported the samples from New Mexico were confirmed positive, along with 5 more cattle herds in Texas (n=7). Four states are now confirmed (Texas, Kansas, Michigan & New Mexico), while confirmation of the presumptive positive results from Idaho remain pending.
It seems likely that additional infected herds will be announced in the days and weeks ahead. While the only positive tests have come thus far from symptomatic dairy cows, it isn't clear how aggressively non-symptomatic cattle are being tested (or if the capacity even exists to do so on a large scale).
The USDA's FAQ, issued on March 29th (see excerpt below) makes it pretty clear they are concentrating primarily on testing symptomatic cattle.
First the statement from the USDA, after which I'll return with a postscript.
Contact:
APHISpress@usda.gov
WASHINGTON, April 1, 2024 – The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the detection of highly pathogenic avian influenza (HPAI) in a dairy herd in New Mexico, as well as 5 additional dairy herds in Texas. APHIS shared on Fri., March 29 that its National Veterinary Services Laboratories (NVSL) in Ames, Iowa, was working to confirm presumptive positive test results from New Mexico, Texas and Idaho herds; this announcement is a follow up to that information.
This marks the first known case of HPAI in cattle in New Mexico, and adds to the two detections in Texas that were first announced on Monday, March 25. To date, USDA has confirmed the detection of HPAI in dairy herds in Texas (7) Kansas (2), Michigan (1), and New Mexico (1). The presumptive positive test results for the Idaho herd are still pending analysis at NVSL.
APHIS continues to work closely with the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), as well as state veterinary and public health officials, to investigate and diagnose activities regarding the illness in dairy cows causing decreased lactation, low appetite, and other clinical signs.
USDA and federal and state partners will continue to share additional updates as information becomes available. APHIS has also prepared a Frequently Asked Questions document, which can be accessed here.
In addition, today, the CDC reported that a person in Texas has tested positive for HPAI A(H5N1) virus; the CDC also stated in its announcement that this infection does not change the A(H5N1) bird flu human health risk assessment for the U.S. general public, which CDC considers to be low. However, people with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection. CDC has interim recommendations for prevention, monitoring, and public health investigations of HPAI A(H5N1) viruses.
Federal and state agencies continue to conduct additional testing in swabs from sick animals and in unpasteurized clinical milk samples from sick animals, as well as viral genome sequencing, to assess whether HPAI or another unrelated disease may be underlying any symptoms.
The NVSL has also confirmed that the strain of the virus found in subsequent states is very similar to the strain originally confirmed in cattle in Texas and Kansas that appears to have been introduced by wild birds (H5N1, Eurasian lineage goose/Guangdong clade 2.3.4.4b). Initial testing has not found changes to the virus that would make it more transmissible to humans. While cases among humans in direct contact with infected animals are possible, this indicates that the current risk to the public remains low.
There continues to be no concern that this circumstance poses a risk to consumer health, or that it affects the safety of the commercial milk supply because products are pasteurized before entering the market. Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted from the commercial milk tank or destroyed so that it does not enter the human food supply. In addition, pasteurization has continually proven to inactivate bacteria and viruses, like influenza, in milk. Pasteurization is required for any milk entering interstate commerce for human consumption. FDA’s longstanding position is that unpasteurized, raw milk can harbor dangerous microorganisms that can pose serious health risks to consumers, and FDA is reminding consumers of the risks associated with raw milk consumption in light of the HPAI detections.
Because of the limited information available about the transmission of HPAI in raw milk, the FDA recommends that industry does not manufacture or sell raw milk or raw/unpasteurized milk cheese products made with milk from cows showing symptoms of illness, including those infected with avian influenza or exposed to those infected with avian influenza. At this time, the FDA is not aware that any milk or dairy product from symptomatic cows is entering interstate commerce. Furthermore, if milk from cows showing symptoms of illness or exposed to those infected with avian influenza, is intended to be used to feed calves or other animals, FDA strongly encourages that it be pasteurized or otherwise heat treated to kill harmful bacteria or viruses, such as influenza, before calf feeding. Food safety information from FDA, including information about the sale and consumption of raw milk, can be found here.
Milk loss resulting from symptomatic cattle to date is too limited to have a major impact on supply and there should be no impact on the price of milk or other dairy products. Further, the U.S. typically has a more than sufficient milk supply in the spring months due to seasonally higher production.
Federal agencies are also working with state and industry partners to encourage producers and veterinarians to report cattle illnesses quickly so that we can monitor potential additional cases and minimize the impact and risk to farmers, farmworkers, consumers and other animals. Producers are urged to work with their veterinarian to report cattle illnesses quickly and practice enhanced biosecurity measures. More information on biosecurity measures can be found here.
While hopefully only symptomatic dairy cows are carrying the HPAI virus, until wider testing is conducted, that assumes facts that are not yet in evidence. And even if non-dairy cows aren't being infected today, that provides no guarantees for the future.
Two weeks ago - despite evidence to the contrary - it was widely assumed that cattle were not susceptible to HPAI (or any influenza A viruses). As a result, it took weeks before anyone thought to test sick dairy cows for avian influenza.
Which means we don't really know how long the virus has been infecting cattle, or how widespread it has become. In the same vein, yesterday's announced (mild) human infection would likely have gone undiagnosed if the alert hadn't been issued a week ago.
In a few southern states some county and state fairs are already underway, with agricultural exhibits of both cattle and swine being well attended events. Those numbers will increase over the summer and fall.
While most fairs require the screening and barring of `sick animals' from exhibition, over the years we've learned that many pigs may be infected asymptomatically (see EID Journal: Flu In Healthy-Looking Pigs and Transmission Of Swine H3N2 To Humans At Agricultural Exhibits - Michigan & Ohio 2016).
It is unknown if HPAI in exhibition cattle will pose a similar risk, but the possibility can't be ignored. It is also reasonable that if cattle and goats are being infected via wild birds, that pigs may be at risk as well.
While large scale testing of cattle or pigs may be impractical, pre-screening of animals prior to exhibition - including the use of RIDTs (Rapid Influenza Detection Tests) - may be worth serious consideration.
Otherwise we risk finding out the hard way that HPAI is more entrenched in livestock than we think.
