Readers with good memories may recall that in July of 2011, in a blog called Korea: Interspecies Transmission of Canine H3N2, I wrote about a study that reported on a recently emerged canine H3N2 influenza virus that had been observed to infect and sicken domestic cats at an animal shelter in South Korea.
This canine H3N2 was of a different lineage than the human H3N2 we have been dealing with since the late 1960s. It first appeared in Korea in 2007 – and unlike the other canine flu (H3N8) -which jumped from equines to dogs, this strain appears to have emerged directly from an avian source.
Daesub Song, Bokyu Kang, Chulseung Lee, Kwonil Jung, Gunwoo Ha, Dongseok Kang, Seongjun Park, Bongkyun Park, and Jinsik Oh
In South Korea, where avian influenza virus subtypes H3N2, H5N1, H6N1, and H9N2 circulate or have been detected, 3 genetically similar canine influenza virus (H3N2) strains of avian origin (A/canine/Korea/01/2007, A/canine/Korea/02/2007, and A/canine/Korea/03/2007) were isolated from dogs exhibiting severe respiratory disease.
To determine whether the novel canine influenza virus of avian origin was transmitted among dogs, we experimentally infected beagles with this influenza virus (H3N2) isolate. The beagles shed virus through nasal excretion, seroconverted, and became ill with severe necrotizing tracheobronchitis and bronchioalveolitis with accompanying clinical signs (e.g., high fever).
Consistent with histologic observation of lung lesions, large amounts of avian influenza virus binding receptor (SAα 2,3-gal) were identified in canine tracheal, bronchial, and bronchiolar epithelial cells, which suggests potential for direct transmission of avian influenza virus (H3N2) from poultry to dogs.
Our data provide evidence that dogs may play a role in interspecies transmission and spread of influenza virus.
Which brings us today to a new study by the same group of researchers that reported on the initial species jump to cats, that looks at laboratory transmission of the canine H3N2 virus to cats, and to ferrets.
Hyekwon Kim, Daesub Song, Hyoungjoon Moon, Minjoo Yeom, Seongjun Park, Minki Hong, Woonseong Na, Richard J. Webby, Robert G. Webster, Bongkyun Park, Jeong-Ki Kim, Bokyu Kang
Article first published online: 23 MAY 2012
Results The interspecies transmission of CIV H3N2 via airborne was only observed from dogs to cats and not from dogs to ferrets. However, direct intranasal infection of either cats or ferrets with CIV could induce influenza-like clinical signs, viral shedding, and serological responses. Additionally, naïve cats and ferrets could be infected by CIV via direct contact with infected animals of the same species.
Conclusion Cats appear to be another susceptible host of CIV H3N2, whereas ferrets are not likely natural hosts. The molecular-based mechanism of interspecies and intraspecies transmission of CIV H3N2 should be further studied.
CIDRAP NEWS published some details not available in the abstract above in their flu news roundup last night.
Follow the link to read:
In a laboratory study, the canine influenza virus (CIV) H3N2 spread from dogs to cats via respiratory droplets, suggesting that cats could be another host for the virus, according to a report published today in Influenza and Other Respiratory Viruses.
<SNIP details of experiment>
"These data suggest that cats, in addition to dogs, can be another susceptible host of CIV H3N2; ferrets may not be susceptible host but may be susceptible after viral adaptation," the researchers write. They say the transmission of the virus between dogs and cats "underscores the concern that these same viruses might also be able to infect humans who come in contact with the animals."
May 23 Influenza Other Respi Viruses
Many of the common illnesses we think of as `human’ diseases actually began in other species, and only later adapted and migrated to humans.
- The scourge of Tuberculosis, which now infects 1/3rd of humanity, probably jumped to humans when man began to corral and raise its traditional hosts; goats and cattle.
- Measles appears to have evolved from canine distemper and/or the Rinderpest virus of cattle.
- Influenza, as most of you know, is native to aquatic birds – but jumped species thousands of years ago and many strains have adapted to humans, pigs, and other species.
The list of zoonotic diseases (those shared between humans and animals) is long and continually expanding, and includes: SARS, Babesiosis, Borrelia (Lyme), Nipah, Hendra, Malaria, Hantavirus, Ebola, Bartonella, Leptospirosis, Q-Fever, bird flu and many, many others.
So understandably, anytime we see a virus – particularly a flu virus – jump species, it gets our attention.
The good news is that so far, these new canine viruses haven’t shown the ability to infect humans.
But as the author’s of the 2008 EID study pointed out:
Transmission of avian influenza A virus to a new mammalian species is of great concern, because it potentially allows the virus to adapt to a new mammalian host, cross new species barriers, and acquire pandemic potential.
And when they infect companion animals, such as dogs and cats, it becomes of even greater concern because of how closely we humans interact with them.