#19,028
As we've discussed often in the past, there has been a decided lack of testing for avian flu in dairy cattle around the world, despite indications that the American spillover of HPAI H5N1 into dairy cattle might not be an isolated event.
That optimistic assumption was challenged in June of 2024, with a statement from Germany's FLI on the Experimental Infection Of Dairy Cows With European H5N1 Virus, and later by reports of H5N1 antibodies found in Pakistani goats and sheep.Initially, only the North American B3.13 strain was believed capable of infecting cattle, which was reassuring to many countries (see DEFRA Risk Assessment Of HPAI H5N1 Occurring in Cattle In the UK).
A little less than a year ago, another genotype (D1.1) was discovered in dairy cattle in Nevada and Arizona, and more recently in Wisconsin, and over the course of the last year we've seen evidence of HPAI H5 antibodies in a sheep from the UK and from Norway.
Last October - more than 18 months after the first detection of HPAI H5 in U.S. cattle - OFFLU released an 11-page statement (see OFFLU Guidelines for High Pathogenicity Avian Influenza Virus Risk Mitigation in Cattle) which called for sweeping changes, including:
- Implementing risk-based bulk milk surveillance
- Enforcing pasteurization and safe disposal of waste milk
- Applying flexible movement controls with testing and quarantines
- Improved biosecurity & milking practices
- Protecting workers with PPE
Late yesterday, the Netherland's Ministry of Agriculture announced the first known detection of avian flu antibodies in European dairy cows, after test results of an apparently healthy cow came back positive.
Testing was conducted because two cats on that dairy farm fell ill from HPAI H5N1 in December. While no active virus was detected, these findings are indicative of previous infection with HPAI.
For now, there is no evidence of further spread, but additional testing is underway. I've posted the (translated) press release below.
Antibodies to bird flu virus found in dairy cow
News item | 23-01-2026 | 19:01
Avian influenza antibodies have been detected in a dairy cow at a dairy farm in the municipality of Noardeast-Fryslân, province of Friesland. No evidence of active viral circulation of avian influenza among the dairy cows on this farm has been found. There are also no signs of avian influenza spreading to other dairy farms.
On December 24, 2025, the Netherlands Food and Consumer Product Safety Authority (NVWA) received a report of two sick cats. One of these cats tested positive for avian influenza and died two days later ( see the letter to Parliament here). Following this report, the NVWA conducted source and contact tracing. This investigation revealed that the cat came from a dairy farm.
On January 15th, the dairy cattle on that farm were screened with a random sample. There were no sick animals present at that time. Analysis of the milk samples by Wageningen Bioveterinary Research revealed that no active virus was present. The presence of antibodies was also tested, which were found in the milk samples from one cow. This indicates a previous infection with the virus in that cow.
The Netherlands Food and Consumer Product Safety Authority (NVWA) visited the farm again on January 22nd. Blood and milk samples were taken from all cattle present. These showed that there was no avian influenza virus on the farm. The results of the antibody tests are expected next week. This will tell us whether more animals have come into contact with the virus. Other mammals on the farm, such as dogs, cats, and horses, are currently and have not shown any symptoms. The people on the farm and the veterinarian are being tested by the Municipal Health Service (GGD).
As far as we know, antibodies against avian influenza have not previously been demonstrated in dairy cattle in Europe. However, there have been numerous avian influenza outbreaks among dairy cattle in the United States. Individual infection of a dairy cow with the avian influenza virus can occur. It is important to know whether this leads to spread within and between farms. There is no evidence that this has occurred.
Read the full message on the Dutch government website
We get a bit more detail, however, from a letter from the MOA to Parliament, and a separate clarification note/addendum to that letter.
Below you'll find some translated excerpts from that letter, where we find that the cow in question was sick with mastitis and respiratory symptoms in December, and 5 PCR tests must be repeated due to errors in the initial testing.
On December 24, 2025, the Netherlands Food and Consumer Product Safety Authority (NVWA) received a report of two sick cats. One of these cats tested positive for avian influenza. The cat in question died on December 26, 2025. The second cat tested negative and has fully recovered. I informed your House of this in my letter of January 13, 2025, with Parliamentary document 28807, no. 322. Following this report, the Netherlands Food and Consumer Product Safety Authority (NVWA) conducted source and contact tracing. This revealed a relevant contact with a dairy farm; the cat in question originated from this dairy farm.
On January 15th, the dairy cattle on this farm were screened. Milk samples were taken from several of the cows present, and a sample was also taken from the bulk milk. At the time of sampling, no animals showing symptoms of illness were present on the farm. The samples were sent to Wageningen Bioveterinary Research (WBVR) for analysis. The results of the PCR tests, which detect the virus in milk, were negative for both the individual samples and the bulk milk sample. This confirmed that no virus was present in the dairy cattle on the farm,
In addition, the samples were tested for the presence of antibodies. On January 20, the WBVR reported that one cow had antibodies against H5N1 avian influenza. The presence of antibodies indicates a previous infection with the virus. The cow in question had suffered from mastitis and respiratory problems in December.
These are symptoms that can be observed in a dairy cow infected with avian influenza. At the time of sampling, this cow had recovered.
Following this positive antibody test, the NVWA (Netherlands Food and Consumer Product Safety Authority) revisited the farm on January 22nd. During this visit, blood and milk samples were taken from all cattle present. A bulk milk sample was also taken again. Today, January 23, 2026, the PCR results of these tests were received.
All but five samples tested negative for individual PCR tests. The bulk milk was also PCR negative. The five remaining individual milk samples resulted in a test error in the laboratory and will be retested this weekend. Based on the PCR results available so far, from last week and today, there is no indication of active avian influenza virus circulation among the dairy cattle on the farm. The final five PCR results will be available this weekend. If these unexpectedly result in a positive outcome, I will inform Parliament immediately.
While hopefully the remaining tests will continue to show this to be an isolated incident, the fact that symptomatic cattle are still not being routinely tested nearly two years after the first American spillover in Texas is concerning.
Had barn cats not fallen ill, and been serendipitously tested for avian flu, this incident might never have come to light.
The Dutch government has acted swiftly once the initial report was received, but sadly testing - even of symptomatic livestock - remains limited both here in the U.S., and and around the globe.
A tactic that might work in the short term, but carries increasing risks as HPAI H5 continues to hone its skills.
