A paper in December’s Emerging Infectious Diseases (Marinova-Petkova et al. 2016) follows up on last year’s outbreak of avian influenza (H7N2) in cats in a New York shelter and one associated human infection (the findings were also summarized in a post from earlier this year). This paper describes investigation of the virus from the infected person and from a cat at the shelter.
The take home message is that the virus from the person and the cat were almost identical, meaning it’s pretty certain that the person was infected by an animal at the shelter. The study also showed that the virus was very similar to a low pathogenicity avian flu strain that was circulating in the US in the early 2000s.
Presumably, this strain is still circulating in birds, and it happened to spill over into a cat (outdoor cats that hunt are at risk of exposure). Then, an infected cat (during the short period it was infectious) happened to enter the shelter, have contact with other cats (again, during that short period when it’s infectious), with transmission to more cats and ultimately a person working with them.
It’s an interesting scenario, for sure. However, it’s not overly concerning.
- We know various flu viruses can periodically infect cats.
- This outbreak burned itself out pretty quickly.
- There was just one known human infection, and it was in someone with close contact with the cats.
- The fact that a cat could get infected, go into a shelter and have contact with other cats in the shelter during what is likely a window of just a few days when it’s infectious is pretty unlikely. Often, strange disease events are “perfect storm” manifestations like this. The odds of any given cat carrying influenza virus at any time are exceptionally low.
This is a good reminder of the potential for inter-species transmission of influenza virus and the potential for pets to act as disease bridges between wildlife and humans. However, it’s important to keep things in context and realize this is an oddball scenario, not a sign of a new serious problem