Dogs are known to be susceptible to influenza A viruses, but information on influenza D virus in canines is limited. Influenza D viruses historically primarily affect cattle with spillover to other animals, but are not known to cause illness in humans.
A new study published in Emerging Infectious Diseases finds that household dogs are exposed to influenza D virus, potentially acting as a source of infection for humans.
The study investigated the seroprevalence of influenza D in 426 dogs in the Apulia region of Italy during 2016 and 2023. A total of 14 samples were positive for Influenza D antibodies, suggesting exposure to Influenza D virus in dogs.
Influenza D virus was first identified from swine exhibiting influenza-like symptoms in 2011 in the United States. Related RNA or antibodies have been detected worldwide in several animal hosts, including cattle, swine, small ruminants, camelids, and wild ungulates, although cattle are the main reservoir.
The study authors conclude that the possibility that some influenza D strains may acquire the ability to evolve and adapt in the human host should not be discounted. This potential risk could be higher in settings where there is more viral pressure, such as in groups with occupational exposure.
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Influenza D virus poses a zoonotic risk to cattle-exposed workers, based on detection of high seroprevalence. Whereas it is still unknown whether IDV causes disease in humans, these studies indicate that the virus may be an emerging pathogen among cattle-workers. (Science Direct)
Influenza D virus infection in feral swine populations, United States
During 2012–2013, study evaluated feral swine populations in 4 US states; of 256 swine tested, 57 (19.1%) were IDV seropositive. Among 96 archived influenza A virus–seropositive feral swine samples collected from 16 US states during 2010–2013, 41 (42.7%) were IDV seropositive. Infection studies demonstrated that IDV-inoculated feral swine shed virus 3–5 days postinoculation and seroconverted at 21 days postinoculation; 50% of in-contact naive feral swine shed virus, seroconverted, or both. (Emerging Infectious Diseases)
Influenza D in domestic and wild animals
Animals associated with humans and susceptible to IDV infection include camels, pigs, small ruminants, and horses. Notably, high seroprevalence towards IDV, apart from cattle, is also observed in camels, potentially constituting a reservoir of the virus. Among wild and captive animals, IDV infections have been confirmed in feral pigs, wild boars, deer, hedgehogs, giraffes, wildebeests, kangaroos, wallabies, and llamas. The transmission potential and host range of IDV may contribute to future viral differentiation. It has been confirmed that influenza D may pose a threat to humans as a zoonosis, with seroprevalence noted in people with professional contact with cattle. (Viruses)