Netherlands - Antibodies to bird flu virus found in dairy cow - January 23+ , 2026 - 5 Cows Now Test Positive

[Pathfinder]

Translation Google
Antibodies to bird flu virus found in dairy cow

News item | January 23, 2026 | 6:44 PM

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.

Safety of milk

The risk of the H5N1 avian influenza virus prevalent in Europe spreading from animals to humans is very small. The risk of humans contracting avian influenza by eating chicken, eggs, or beef, or through dairy products, is also very small. Eggs, meat, and milk meet strict requirements. For example, dairy products are heated to a temperature that kills viruses. Furthermore, the milk from the previously infected cow has not been processed for human consumption due to the existing mastitis pattern. However, it is important not to consume raw dairy products from a cow infected with avian influenza.

The bird flu situation in the Netherlands remains worrisome. The situation is being closely monitored, and all stakeholders have been asked to remain alert for any potential signs.

Documents

• Dairy cow with antibodies against bird flu
  
  Dairy cow with antibodies against bird flu
  Parliamentary document: Letter to Parliament | 23-01-2026

https://www.rijksoverheid.nl/minist...istoffen-vogelgriepvirus-gevonden-bij-melkkoe
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See also:

https://flutrackers.com/forum/forum...13-netherlands-kittens-die-from-h5n1-bird-flu

 

[Michael Coston]

Netherlands: NVWA Announcement on Avian Flu Antibodies Detected In Dairy Cow

#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.

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).​

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.

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

A few weeks later, WOAH issued their own statement (see WOAH Statement (Oct 22nd): High Pathogenicity Avian Influenza (HPAI) in Cattle), which closely aligned with the earlier OFFLU report.

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.


https://afludiary.blogspot.com/2026/01/netherlands-nvwa-announcement-on-avian.html
​

 

[Pathfinder]

Hat tip to Michael Coston

More from the Ministry of Agriculture's letter addressed to Parliament:

Translation Google
...
Safety of the milk

The NVWA's Bureau for Risk Assessment and Research (BURO) has previously conducted research at the request of the Ministry of Health, Welfare and Sport into the management of food and feed safety risks of the HPAI virus in milk³. In this research It is confirmed that pasteurizing milk completely inactivates the avian influenza virus present. The milk is then safe for human consumption and poses no risk to public health or the spread of the virus. It is important that raw milk and raw-milk dairy products from cows infected with avian influenza are not consumed.

Monitoring dairy cattle

Individual infection of a dairy cow with avian influenza virus can occur.

It is important to know whether this leads to spread within and between farms. There are currently no indications that this is the case. The basic animal health monitoring program conducts a so-called syndrome surveillance, which involves weekly national and regional monitoring of bulk milk deliveries to determine whether there are any animal health problems in dairy cattle. This is a sensitive tool that is particularly valuable when new conditions arise that do not produce specific or noticeable symptoms. In addition, the basic monitoring program utilizes pathological examination, and unexplained problems can be reported to the Veekijker (Livestock Viewer). This also makes it possible to identify individual suspected cases of avian influenza infection.

To date, the basic monitoring has not found any indications that suggest avian influenza infection in dairy cows. Naturally, I am closely monitoring the situation and have asked all stakeholders to do so. In the short term, I will ask the experts to provide a risk assessment. I will also ask experts to analyze possible infection routes and to assess the effectiveness of HPAI monitoring in cattle. Furthermore, I have informed stakeholders about this new situation and asked them to report any notable findings.

Public health risk

Based on the currently available data, the RIVM (National Institute for Public Health and the Environment) estimates the risk to public health to be very low. Because the other cows on the farm also tested negative in the PCR test, it seems unlikely that the virus could have spread from the cow to the others. Due to the cat that previously tested positive near the farm, people working or living on the farm were already known to the Municipal Health Service (GGD). These people have not shown any symptoms consistent with (avian) flu since then. To be on the safe side, all people exposed to the cow will still be offered testing for an active or past infection.

At this farm, milk is used only for pasteurized products, meaning any virus present is inactivated and poses no risk of external contamination. Furthermore, the milk from the previously infected cow was not processed for human consumption due to the existing mastitis condition.

This means that there is very little chance that virus from the infected cow has ended up in the milk for human consumption.

In view of the new situation, the RIVM will organize a Zoonosis Response Team (RT-Z) in the short term in line with the existing zoonosis structure, in which Experts from human and veterinary health will make a risk assessment based on the new situation and share it online.

Finally

The avian influenza situation in our country remains worrying. Unfortunately, outbreaks have occurred in recent weeks on both commercial poultry farms and hobby farms. Wild birds are also regularly found infected with avian influenza. The fact that a dairy cow has been infected with the avian influenza virus is therefore consistent with these times of high infection pressure. Nevertheless, this is a worrying development. I will therefore continue to closely monitor this situation and will conduct further research. I will, together with the Minister of Health, Welfare and Sport, inform you of any relevant developments regarding avian influenza and this case.

Yours faithfully,

Femke Marije Wiersma

Minister of Agriculture, Fisheries, Food Security and Nature

​
Parliamentary document: Letter to Parliament | 23-01-2026

​https://open.overheid.nl/documenten/b45c5635-ad86-4948-a225-97941213bd0a/file

 

[Pathfinder]

Detection of avian flu antibodies in Dutch dairy cow: ECDC risk assessment remains unchanged

News
27 Jan 2026

With avian influenza A(H5N1) widely circulating in wild birds and poultry, and repeatedly detected in mammals, Dutch public health authorities report that antibodies indicating past exposure have been identified in milk from a dairy cow in the Netherlands. No other cows on the affected farm have tested positive for the virus and no exposed people have developed symptoms, but investigations are ongoing.

As yet, there have been no confirmed human cases of A(H5N1) in the EU//EEA and ECDC’s risk assessment remains unchanged. The current risk is assessed as low for the general population and low to moderate for people with occupational exposure (e.g. poultry farm workers) or other exposure to infected animals or contaminated environments (e.g. direct contact with infected wild birds).

Transmission of avian influenza from cattle to humans has only been reported in the United States among farm workers exposed to infected cattle or contaminated environments, and such cases remain sporadic and all developed only mild symptoms.

As highlighted in the ECDC/EFSA Scientific Opinion on preparedness, prevention and control of avian influenza, adherence to biosecurity measures is essential, alongside enforcing proper protective measures for people exposed to potentially infected animals and the early detection of animal-to-human influenza transmission.

ECDC has produced a guide for pre-pandemic zoonotic influenza preparedness and response to help European countries respond to possible animal-to-human influenza threats. This guide sets out practical response actions across a range of scenarios.

ECDC is monitoring the situation together with partner organisations in Europe and will continue to update its assessment of the risk for humans in the EU/EEA as new information becomes available. 

Further information


ECDC regularly monitors zoonotic avian influenza strains through its influenza surveillance programme and epidemic intelligence activities in collaboration with the European Food Safety Authority (EFSA) and the EU Reference Laboratory for Avian Influenza to identify significant changes in the virological characteristics and epidemiology of the virus. Together, they produce a quarterly updated report on the avian influenza situation.
​
...

https://www.ecdc.europa.eu/en/publi...-dutch-dairy-cow-ecdc-risk-assessment-remains

 

[Michael Coston]

Netherlands: NOS.NL Reports 5 Dairy Cows Have Now Tested Positive for H5N1

#19,035

Although I have yet to find any official statement posted on a NL government website, NOS (Nederlandse Omroep Stichting) - the Netherland's Public Broadcasting Network - is reporting that last night Agriculture Minister Femke Wiersma notified the House of Representatives that testing now reveals Five cows with antibodies against bird flu in Northeast Friesland.

This story has also been picked up by AgriHolland and BoerderiJ.​

The last official statement I can find was on January 23rd (see Netherlands: NVWA Announcement on Avian Flu Antibodies Detected In Dairy Cow), after an investigation into 2 sick barn cats (1 died from H5N1) led to the detection of a single dairy cow with antibodies to HPAI.

Initial reports strongly suggested this was an isolated incident, stating `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.'​

Despite this reassuring report, a separate letter to Parliament indicated that 5 tests came back with `errors', and would be repeated (see excerpt below).

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. ​

NOS quotes Minister Femke Wiersma as stating during a debate on zoonoses last night at the House of Representatives; "It now appears, and this is new information, that antibodies have been found in five different cows."

Hopefully we'll get more information in the hours ahead.


https://afludiary.blogspot.com/2026/01/netherlands-nosnl-reports-5-dairy-cows.html
​

 

[sharon sanders]

Please see our Netherlands forum for wild bird, mammal, poultry avian flu reports from the government, WOAH, various news:

https://flutrackers.com/forum/forum/europe/h5n1-tracking/netherlands

 

[Pathfinder]

Translation Google

Five cows tested positive for bird flu antibodies

NewsPoliticsPeter SmitJ anuary 29, 2026 at 8:57 P Mo'clock

At the Frisian dairy farm where avian influenza antibodies were found in one cow last week, a total of five cows have been infected. This is according to additional research conducted at the farm by the Netherlands Food and Consumer Product Safety Authority (NVWA).

Minister of Agriculture Femke Wiersma announced the new cases Thursday evening during a debate on zoonosis and animal diseases. Last Friday, it was announced that a cow on the Frisian farm had antibodies against the bird flu virus, indicating that the cow had been infected with the virus.

It was the first time in Europe that antibodies against avian influenza were found in dairy cattle. This has happened before in the United States. No active virus was found on the Frisian farm, only antibodies. All those who had been in contact with the cows tested negative.

Risk assessment

Blood tests were performed on all animals at the Frisian dairy farm. The Minister expects the results and a risk assessment by experts next week. Whether any measures are necessary – such as monitoring bulk milk – remains to be seen.

When asked whether milk from infected cows is safe to drink, the minister replied that it's not "necessarily unsafe." She pointed out that milk is pasteurized. In that case, she said, the risk of virus transmission is eliminated. Next week, experts are expected to provide more clarity on this, including whether raw milk is safe to drink.

https://www.nieuweoogst.nl/nieuws/2026/01/29/vijf-koeien-positief-op-antistoffen-vogelgriep

 

[Pathfinder]

Translation Google

​
Stenogram:
Two-minute debate on Zoonoses and Animal Diseases (CD 14/1) (uncorrected)
Download
​
https://www.tweedekamer.nl/kamerstukken/detail?id=2026D04429&did=2026D04429

--------------------------------------------------------
An excerpt from page 10 of the document:

The Chairman:

Thank you, Minister Bruijn. We will now move on to Minister Wiersma for the answers to a number of questions and the assessment of the motions.

Minister Wiersma:

Thank you. I believe I have a number of motions to address, but I would like to start with a brief introduction. Last week, together with the Minister of Health, Welfare and Sport, I informed Parliament about the case of avian influenza in dairy cattle. Since this is naturally being referred to in this debate, I would like to provide an update on the situation. We informed your Parliament about this on Friday. I want to emphasize that the test results currently show that no active virus has been found on the farm. All cows have been monitored, and all virus tests of the milk from this farm have fortunately been negative. I also wrote in the letter that a number of cows, five in total, had to be retested. Those results also turned out to be negative. In this case, that is positive. We also reported that the Netherlands Food and Consumer Product Safety Authority (NVWA) has taken samples from all individual cattle on the farm. These are all being tested for antibodies against the avian influenza virus. This is being done by Wageningen Bioveterinary Research. The new information that I would like to share with your Parliament is that it has ultimately become clear that antibodies have been found in five different cows, but, again, no active virus. Blood samples have also been taken from all animals and these are also being tested for antibodies. These investigations take time. Wageningen would like to conduct additional research to be able to provide complete certainty about the results. This is being done in close consultation with the European Reference Laboratory. The people who were exposed to both the cows and the cat that had previously tested positive also all tested negative. Ultimately, I expect that a complete picture with all the test results will be available next week. This is also necessary to provide the experts who deal with this issue and advise the government with a complete picture and to allow them to interpret the situation. My goal is to then take all the information – which includes not only the information from this company, but also the risk assessment from the experts, the possibilities for monitoring, and any measures that may need to be taken – and present it to Parliament in a comprehensive manner.​
...

 

[sharon sanders]

As usual some trolls on social media are claiming they "had this story first" but please check the time stamp above in post #1 at January 23, 2026, 07:11 PM for the ministry's announcement.

In reality, the ministry had the story first with their time stamp of "23-01-2026 | 18:44" which is 12:44 ET. link

I don't have the words. Everyone here is a volunteer.

 

[tetano]

Eurosurv. Detection of antibodies against avian influenza in European dairy cattle, the Netherlands, January 2026

Monika Z Ballmann[SUP]1[/SUP] , Luca Bordes[SUP]1[/SUP] , Kim M Bouwman[SUP]1[/SUP] , Marc Y Engelsma[SUP]1[/SUP] , Sandra Venema-Kemper[SUP]1[/SUP] , Sylvia BE Pritz-Verschuren[SUP]1[/SUP] , Rene Heutink[SUP]1[/SUP] , Marit Roose[SUP]1[/SUP] , Marcel AH Spierenburg[SUP]2[/SUP] , Arco van der Spek[SUP]2[/SUP] , Hendrik IJ Roest[SUP]3[/SUP] , Evelien A Germeraad[SUP]1[/SUP] ​

Abstract

In December 2025, highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b genotype DI.2.1 virus was detected in a cat living on a dairy cattle farm. Milk and serum samples from the dairy cattle were tested for avian influenza virus. No viral RNA was detected; however, H5N1-specific antibodies were identified in serum samples from 34 (47.2%) of 72 lactating dairy cows and 24 (63.2%) of 38 youngstock. These demonstrate expansion of the mammalian host range of HPAI H5N1 in Europe.

https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2026.31.25.2600464#html_fulltext


​

 

[Michael Coston]

Eurosurveillance: Detection of antibodies against avian influenza in European dairy cattle, the Netherlands, January 2026

Eurosurveillance: Detection of antibodies against avian influenza in European dairy cattle, the Netherlands, January 2026

#19,221

Last January (see Netherlands: NVWA Announcement on Avian Flu Antibodies Detected In Dairy Cow) we learned of the detection of H5N1 antibodies in a European cow on a Dutch farm following an investigation into 2 sick barn cats, one of which died from H5N1.

A week later, we saw a cryptic report from NOS (Nederlandse Omroep Stichting) - the Netherland's Public Broadcasting Network - indicating that a total of 5 Dairy Cows Had Tested Positive for H5N1 antibodies.​

None of the cows were reported sick, and none tested positive by PCR, suggesting these were past infections, not current (see ECDC Statement On H5N1 Antibodies in Dutch Dairy Cow: ECDC Risk Assessment Remains Unchanged).

Since then, we've heard very little about this apparent outbreak.​

Yesterday, the ECDC Journal Eurosurveillance published the first detailed account of the investigation, where we learn that - on this one farm - there were literally scores of animals with detectable H5N1 antibodies, not five.

Reassuringly, `oropharyngeal swabs collected from members of the farmer's family tested negative for avian influenza virus', but there is only a narrow window (which had likely passed) where PCR tests would be useful in detecting the virus.

If antibody testing was performed on the family, it wasn't reported in this study. Notably, there is also no mention of testing of livestock on any surrounding farms. Hopefully there are other studies in the pipeline.​

The bottom line is that more than half the livestock tested on this one farm carried antibodies for H5N1, and the source of their infection, and the mode of in-farm transmission, remain murky.


I've only posted the link, and some excerpts, from the study. Follow the link to read it in its entirety.

Detection of antibodies against avian influenza in European dairy cattle, the Netherlands, January 2026
Monika Z Ballmann1 , Luca Bordes1 , Kim M Bouwman1 , Marc Y Engelsma1 , Sandra Venema-Kemper1 , Sylvia BE Pritz-Verschuren1 , Rene Heutink1 , Marit Roose1 , Marcel AH Spierenburg2 , Arco van der Spek2 , Hendrik IJ Roest3 , Evelien A Germeraad1​

Since March 2024, a large-scale outbreak of highly pathogenic avian influenza (HPAI) H5N1 virus has affected dairy cattle in the United States (US) [1]. In contrast, no evidence of HPAI H5N1 infection in dairy cattle associated with the European genotype DI.2.1 has been reported up to date. Here we describe a case investigation and a farm-level survey that resulted in the first reported detection of antibodies against HPAI H5N1 in dairy cattle in Europe.

Case description and virological investigation of the cat

On 24 December 2025, nasal, rectal and conjunctival swabs were collected and submitted for diagnostic testing from a 4-month-old domestic cat living on a dairy cattle farm and exhibiting clinical signs, lethargic and respiratory signs, consistent with HPAI virus infection. The cat died 2 days later. All three swab samples tested positive for influenza A virus by RT-qPCR [2], and the virus was identified as HPAI H5N1 clade 2.3.4.4b genotype DI.2.1 using Illumina whole genome sequencing [3]. Phylogenetic analysis demonstrated that the virus clustered with HPAI H5N1 viruses associated with outbreaks among wild and domestic birds across Europe since October 2025 (Figure 1).​

The HPAI H5N1 virus detected in the cat did not contain the PB2 M631L substitution that has been frequently reported in the B3.13 genotype in the US, infecting dairy cattle. The PB2 E627K substitution, a well-characterised marker of mammalian adaptation, was present. Furthermore, the PB2 I292V substitution, which was rarely observed in earlier European HPAI H5N1 viruses, but now predominantly identified in the DI genotypes, was detected. No other previously identified genetic markers known to influence virulence, host specificity or binding of host proteins were identified in the cat sequence.​

Investigation of dairy cattle and milk​

Following the detection of HPAI H5N1 virus in the cat, dairy cattle from the same farm were tested for avian influenza viruses and antibodies as part of an epidemiological investigation. On 15 January 2026, 20 individual milk samples (midstream milk from all four udder quarters in a single tube) and a bulk tank milk sample were collected. No viral RNA was detected in any of the milk samples by RT-qPCR targeting the matrix gene (M-PCR) [2]. However, antibodies against influenza A virus were detected in nine individual milk samples and the bulk tank milk sample with nucleoprotein (NP)-ELISA (ID Screen Influenza A Antibody Competition Multispecies, Innovative Diagnostics (ID), Grabels, France).​

The farm was revisited on 22 January 2026: individual milk (n = 70) and serum (n = 72) samples were obtained from all lactating dairy cows and serum samples from the 38 youngstock (aged 1–2 years)​

(SNIP)​

Discussion​

Since March 2024, a large-scale outbreak of HPAI H5N1 clade 2.3.4.4b viruses belonging to the B3.13 and D1.1 genotypes has been reported in dairy cattle in the US [1]. While Eurasian-lineage HPAI H5N1 clade 2.3.4.4b viruses have infected multiple mammalian species [6], including cattle under experimental conditions [7,8], to our knowledge, we report the first detection of H5N1-specific antibodies in European dairy cattle.

In the US, HPAI virus infection in dairy cattle appeared to be mostly asymptomatic or associated with non-specific clinical signs, mastitis, a rapid decline in milk production, reduced feed intake and rumination, lethargy and mild elevation in body temperature [9]. In our report, one lactating cow had clinical mastitis in all four udder quarters. Although the observed clinical signs were consistent with HPAI virus infection, no samples from the symptomatic animal at the time of clinical manifestation were available for testing for influenza virus; therefore, the involvement of other pathogens cannot be excluded.​

During the investigation, antibodies were detected in more than 50% of the animals suggesting a predominantly subclinical presentation and highlights that infection in dairy cattle may remain undetected without targeted surveillance. While milk is a sensitive matrix for detecting HPAI virus during acute infection in dairy cattle [10], our results indicate that serum could be more suitable for serological surveillance, as antibody titres were higher in serum (VNT titres > 2,048 and up to 40 by HI) than in milk (VNT titres up to 128 and HI titres 0) from the same individual. This finding is consistent with findings from a previous study indicating VNT titres up to 813 in serum and up to 512 in milk [7]. Antibody waning may occur at different rates in serum and milk over time, which may explain the relatively large difference in VNT and HI titres observed in this investigation, but longitudinal studies assessing antibody waning in both serum and milk are currently lacking.

The exact source and route of virus introduction in the cat and cattle remain unclear. The farm is in an area frequented by overwintering birds that grazed on the same grasslands as the cattle. Increased wild bird mortality was observed in the area during October and November 2025. Bird carcasses were removed from the grassed pastures by the farmer but not submitted for virological testing. Around the last weekend of November 2025, dairy cattle and youngstock were moved indoors for the winter, while the cat continued to have access to the fields. The cat may have acquired the virus through consumption of an infected bird or contaminated milk from infected cattle. Cattle exposure may have occurred via contaminated environment, feed or direct contact with wild birds.​

The high proportion of dairy cows and youngstock with antibodies suggests either a high level of primary exposure or the possibility of cow-to-cow transmission. Further investigation is required to clarify transmission dynamics.

In this study, oropharyngeal swabs collected from members of the farmer's family tested negative for avian influenza virus. Although, since the onset of the outbreak of HPAI H5N1 virus in cattle in the US, occasional human infections have been reported. To date, no sustained human-to-human transmission has been documented. Current public health assessments consider the risk of clade 2.3.4.4b H5N1 viruses to the general population to be low, with human cases limited to sporadic infections following close contact with infected poultry or dairy cattle [11,12]. Consumption of raw milk or unpasteurised dairy products may also pose a risk of virus exposure [13].​

Conclusion​

We report detection of antibodies in Europe against the Eurasian lineage of H5N1 virus in dairy cattle, identified after a cat living on the same farm tested positive. Infection of a mammalian livestock species with frequent human contact warrants continuous attention, as it increases opportunities for virus transmission and subsequent adaptation and underscores the importance of integrated surveillance on the animal-human interface.​

(Continue . . . )



Despite the aggressive spread of H5N1 in dairy cattle in the United States since 2024, livestock surveillance in Europe remains limited, based (in part) on the belief that the B3.13 genotype in North America was somehow unique in its ability to infect cattle (see DEFRA Risk Assessment Of HPAI H5N1 Occurring in Cattle In the UK).

This, despite the fact that over the summer of 2024 the FLI successfully infected cattle with a contemporary European H5N1 virus, finding it replicated efficiently in bovine mammary tissue and could produce adaptive mutations (PB2 E627K) during replication, and the 2025 discovery that genotype D1.1 could also infect cattle.​

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

A few weeks later, WOAH issued their own statement (see WOAH Statement (Oct 22nd): High Pathogenicity Avian Influenza (HPAI) in Cattle), which closely aligned with the earlier OFFLU report.

How diligently these guidelines are now being followed in Europe - and the rest of the world - is unknown.​

This report should be (another) wake up call that livestock outside of the United States can no longer be assumed to be somehow immune to H5N1, and that bulk milk testing may not be sensitive enough to reliably detect the virus in dairy cows.

Assuming anyone is listening, that is.

https://afludiary.blogspot.com/2026/06/eurosurveillance-detection-of.html


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