At this point in time, there are as many unknowns as knowns regarding the currently circulating highly pathogenic avian influenza virus (HPAI) H5N1 strain.
The unknowns have fostered much speculation. Some of the speculations are rational, plausible scenarios and can guide us to answers – but ultimately they are “good guesses” until proven or disproven.
A known is that millions of wild and domestic birds have been infected with the virus all around the world and many have died. In January 2024, researchers discovered that some Falkland Islands penguins were infected and several died. This raised concerns for the various species that inhabit Antarctica.
At the same time, scientists tested 16 penguins on Beagle Island in the Antarctic peninsula. Seven were positive. As of early March, the penguins were alive and foraging normally two months later. The concern is that these penguins could be asymptomatic spreaders of the virus that could kill other species.
Bear in mind, the aforementioned penguins are not the same species. The Falkland Islands penguins are Gentoo. The Beagle Island penguins are Adélie.
Another known is that many mammalian species have contracted the virus and died. The main route of known transmission is fairly obvious: consumption of and exposures to infected birds, their feces, or carcasses. However, as the British Antarctic Survey put it, “Cases have also been noted in some marine mammals where this mode of transmission would not apply.” The same goes for the transmission of H5N1 amongst dairy cattle.
So, the primary unknowns right now are if and how the virus is circulating amongst mammals within the same species or others and the environment with the additional variables of:
- route of transmission;
- genotype of virus;
- current diseases or infections that compromise the immune system;
- the overall environment;
- amount of exposure in terms of time and contact; and,
- cleanliness.
Case in point, the second diagnosed human case in the United States was in a farm worker who had prolonged exposure to H5N1-infected dairy cattle and a developing case of conjunctivitis. However, the Centers for Disease Control & Prevention (CDC) will not definitively say the cows spread it to the worker or vice versa. The agency needs more evidence.
The CDC noted: “The PB2 of the human specimen had a change of PB2 E627K compared to the PB2 genes of viruses available from USDA detections in Texas dairy cattle and typically found in A(H5N1) viruses circulating in wild birds. This mutation is, however, commonly found in humans and other mammals that are infected with HPAI A(H5N1) viruses and is understood to be associated with mammalian adaptation because it improves RNA polymerase activity and replication efficiency in mammalian cells; based on experimental studies in mice, guinea pigs and ferrets, it has the potential to impact pathogenesis or transmission in infected mammals. Despite previous identification of PB2 E627K in human cases of HPAI A(H5N1) virus, there is no evidence of onward transmission among humans after infection with viruses containing this mutation. It is important to note that this substitution has not been seen in available PB2 genes from viruses circulating in wild birds and poultry or in the recently described cattle viruses detected in Texas, suggesting the mutation may have been acquired in the patient during the development of conjunctivitis.”
While the CDC, World Organisation for Animal Health (WOAH), United States Department of Agriculture (USDA) and the other agencies are busy studying it all, we will continue to focus on prevention of H5N1 in companion pets.
Indeed, sick and H5N1-infected cats were found at farm facilities by the Texas Department of State Health Services.
Transmission of H5N1
It is known that infected birds transmit avian flu through:
- Saliva
- Mucous
- Feces
- Body (i.e. when a cat eats a bird)
H5N1 Symptoms in Cats and Dogs
- Listlessness
- Loss of appetite
- Depression
- Fever
- Difficulty breathing
- Neurological disease
- Respiratory and gastrointestinal signs
- Jaundice
- Death
Prevention
The best course of action at this time is to limit exposure.
- Avoid contact between pets (e.g., pet birds, dogs and cats) with wild birds.
- Do not allow your companion dog to eat bird or goose feces.
- Try to limit an indoor/outdoor cat’s territory to a fenced-in backyard. Before letting cats or dogs out, check the fenced-in area for any sick or dead birds, and follow the guidelines below.
- 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).
- Avoid touching your mouth, nose, or eyes after contact with birds or surfaces that may be contaminated with saliva, mucous, or feces from wild or domestic birds.
- Wash your hands with soap and warm water for at least 30 seconds after touching birds or other sick animals – just like you should do for exposure to SARs-CoV-2/COVID-19.
- Change your clothes after contact with wild birds, poultry and sick animals.
Additional References
Dodds, Jean. What We’re Watching: Highly Pathogenic Avian Influenza Virus H5N1, Hemopet, 13 May 2023, https://hemopet.org/what-were-watching-highly-pathogenic-avian-influenza-virus-h5n1/.
GF-Tads Meeting: Detection of HPAI in Ruminants and Humans in the USA, World Organisation for Animal Health, 5 Apr. 2024, https://rr-americas.woah.org/en/news/gf-tads-meeting-detection-of-hpai-in-ruminants-and-humans-in-the-usa/.