Cats As Potential Vectors/Mixing Vessels for Novel Flu
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In 2006, virologist C. A. Nidom of the Institute of Tropical Disease, Airlangga University demonstrated that of 500 cats he tested in and around Jakarta, 20% had antibodies for the H5N1 bird flu virus. Findings that prompted the FAO in 2007 to warn that: Avian influenza in cats should be closely monitored.
In 2012 the OIE reported on Cats Infected With H5N1 in Israel, in 2015 we saw the Guangxi Zoo Reports 2 Tiger Deaths Due To H5N1 and reports of Fatal H5N6 Avian Influenza Virus Infection in a Domestic Cat and Wild Birds in China.
In late 2016 we saw an epidemic of avian H7N2 sweep through several New York City animal shelters, infecting hundreds of cats, and infection several staff members (see J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016).
More recently we've seen scattered reports of cats infected with HPAI H5N1 (see here, here, and here), along with two high profile outbreaks last summer - in Poland and in South Korea. While the South Korea outbreak was quickly traced to locally produced cat food, we've heard very little from Poland's investigation.
You can find a more comprehensive history of avian influenza in A Brief History Of Avian Influenza In Cats.
Yesterday Utrecht University published plans to conduct a serosurvey of cats this winter (see below) in order to gauge how prevalent spillover of the virus to cats is in the Netherlands. Results are expected next summer.
First their announcement, then I'll return with a bit more after the break.
Research into the risks of bird flu in domestic cats
1 november 2023
The Faculty of Veterinary Medicine is conducting a study on behalf of the Ministry of Agriculture, Nature and Food Quality into the presence and risks of bird flu in domestic cats. Given the possible zoonotic risks, Minister Adema believes it is important to gain more insight into this.
For the time being, the risk of bird flu transmission between animals and humans is low. There are no known cases of people becoming infected through contact with a cat. There have also been no reports of sick or dead cats with bird flu in the Netherlands so far.
However, the ministry would like to gain more insight into infections in domestic cats, precisely because these cats come into very close contact with people. The research is conducted under the supervision of Josanne Verhagen of the Virology department and Els Broens of the Veterinary Microbiological Diagnostic Center (VMDC) of the Faculty of Veterinary Medicine. Els Broens, head of the VMDC: “We ask veterinary practices with which we work to send blood samples from domestic cats that come outside. Of course, this only happens with the owner's permission.
If outdoor cats catch birds with bird flu, there is a chance that they will become infected. We are particularly interested in cats from wetland areas with many wild birds.” In the coming months, the researchers want to examine 200 to 300 samples for antibodies against the bird flu virus.
Previous research
Previous research by the Faculty of Veterinary Medicine among 1,500 cats in the period 2020-2023 found cats with antibodies against the bird flu virus. This mainly concerns stray cats (without owners). During a castration project, these cats were examined for antibodies against various viral infections, including bird flu. The stray cats came from 72 different locations.
Of the 701 stray cats examined, 83 stray cats were found to have antibodies against the bird flu virus. A number of the stray cats examined had mild symptoms, but not specifically for bird flu. Eating infected dead birds is a likely route of infection for these stray cats. An analysis of various risk factors showed that stray cats from nature reserves had, on average, more antibodies against the bird flu virus than stray cats from other habitats, such as a livestock farm, holiday park or industrial area.
In domestic cats, 4 of the 814 blood samples examined had antibodies against the bird flu virus. The blood samples from the domestic cats were sent to the Faculty for blood testing for various reasons. These were therefore not part of the castration project, but were added to this part of the study as a control group. Among domestic cats, there was an overrepresentation of cats from urban areas in the Randstad and it is not known whether these cats came outside and therefore possibly had contact with (wild) birds. The faculty wants to gain more insight into this with the new research into domestic cats that come outside. The study is expected to be completed by mid-2024.
Stay alert
In three Polish cities, cats died in the spring of 2023 with symptoms consistent with bird flu. Polish authorities have indicated that 35 cats have tested positive for highly pathogenic bird flu (HPAI) virus, type H5N1. Although the viruses from different cats were closely related in genetics, no common source of infection has been found. Some of the dead Polish cats did not go outside, which makes contamination by wild birds unlikely. In recent times, infections in cats have also been reported in other countries, such as France, Italy, Canada and South Korea.
Although there have been no reports of sick or dead cats with bird flu in the Netherlands to date, it is important for owners of outdoor cats to remain alert around contact with sick birds. The Ministry of Agriculture, Nature and Food Quality advises cat owners to go to the vet if symptoms of illness occur. Information for owners about bird flu in cats can be found on the government website .
While the risks of pet owners contracting avian flu from their cat (or dog) is very low, it is not zero. The CDC maintains a website for pet owners which has the following advice.
If your domestic animals (e.g., cats or dogs) go outside and could potentially eat or be exposed to sick or dead birds infected with bird flu viruses, or an environment contaminated with bird flu virus, they could become infected with bird flu. While it’s unlikely that you would get sick with bird flu through direct contact with your infected pet, it is possible.
For example, in 2016, the spread of bird flu from a cat to a person was reported in NYC The person who was infected [2.29 MB, 4 pages] was a veterinarian who had mild flu symptoms after prolonged exposure to sick cats without using personal protective equipment.
If your pet is showing signs of illness compatible with bird flu virus infection and has been exposed to infected (sick or dead) wild birds/poultry, you should monitor your health for signs of fever or infection.
Take precautions to prevent the spread of bird flu.
As a general precaution, people should avoid direct contact with wild birds and observe wild birds only from a distance, whenever possible. People should also avoid contact between their pets (e.g., pet birds, dogs and cats) with wild birds.
Don’t touch sick or dead birds, their feces or litter, or any surface or water source (e.g., ponds, waterers, buckets, pans, troughs) that might be contaminated with their saliva, feces, or any other bodily fluids without wearing personal protective equipment (PPE). More information about specific precautions to take for preventing the spread of bird flu viruses between animals and people is available at
Additional information about the appropriate PPE to wear is available at Backyard Flock Owners: Take Steps to Protect Yourself from Avian Influenza
