CIDRAP: "Contaminated meat likely source of avian flu that killed bush dogs in UK zoo, preprint suggests"
'Likely' is an interesting choice. Let's take a look at the alternative transmission possibilities noted in the study:
* scavenging of wild bird carcases/sick wild birds landing in the un-netted pen
* indirect contact (e.g., wild bird faeces)
Both of these possibilities can involve bioaerosols
"Wild bird activity was observed on the site during epidemiological investigations"
(Cont.) 🧵
The study's basis for suggesting that it was foodborne includes the speed of onset, but that isn't necessarily an airtight conclusion. Notably, the airways of the dogs were infected, which means airborne transmission was entirely possible. Dogs are also, like many animals, messy eaters, and it is possible that infected particles from scavenged birds -- like fecal aerosols -- were inhaled during the process of consumption
I had the same thought, especially because there were no die-offs noted in the wild bird population where they were shot, but, this threw at least some cold water on the idea:
"Time-resolved phylogenetic and amino acid analysis found that all the sequences from the bush dogs were the result of a single introduction, however whilst there were amino acid substitutions, these do not appear to have been consistently maintained. Taken together, this suggests that transfer between dogs is unlikely, and that a common source of infection is responsible, although it is impossible to definitively conclude whether dog-to-dog transmission occurred. Critically, of the original bush dog population within the enclosure, 5 animals survived remaining clinically normal throughout. This may indicate that these dogs had not received a dose of virus sufficient to drive a productive infection. This is further supported by low level serological responses being detected in two of the animals (cases 11 and 12) that may indicate exposure to antigen or a low-level infection that was cleared by the host immune response."
Also:
"From the perspective of zoonotic risk, the well-established marker of mammalian adaptation (E627K) was detected in all but one of the bush dog sequences generated."
Seems to indicate that the source was likely non-mammalian. But I agree, it's not an airtight case that there was zero mammal to mammal transmission.
Thanks for pointing out the paper! It was a little morbid, but I learned some things.
https://www.biorxiv.org/content/10.1101/2024.04.18.590032v1.full
@BE
I am particularly interested in the fecal aerosol angle lately. It is interesting that there weren't local die-offs. If live, wild birds are -- pardon my language -- shitting and farting everywhere, it seems difficult to rule out the role this route might be playing