A Dog & Cat Flu Review

 

# 9382

 

Until about a decade ago, it was widely (and erroneously) believed that dogs and cats were not generally susceptible to influenza A infections. 

 

That perception began to change in 2004 with two unrelated events; the jump of equine H3N8 influenza from horses to Florida greyhounds, and the infection by avian H5N1 of tigers fed infected chickens in Thailand.

 

While not considered major players (yet) in the spread of human or novel influenza viruses, their role as companion animals make dogs and cats of particular interest to influenza researchers.

 

First a look back at some of the evidence on dogs & cats susceptibility to influenza – then I’ll have a couple of new studies that shed additional light on their ability to contract, and spread, certain subtypes of flu.

 

In 2004, the H3N8 equine influenza – a strain that has been around in horses nearly a half century – was discovered to have jumped, and adapted to dogs, creating a new dog-specific (canine) lineage of H3N8. 

 

Since then, H3N8 has continued to spread among dogs both in North America and around the globe.

While we’ve yet to see any evidence that this equine/canine H3N8 virus can infect humans, there are a number of different H3N8 lineages out there, including the equine, canine, avian, and even a recently discovered Mammalian Adapted H3N8 In Seals.

And a related H3N8 virus is thought to have sparked the 1900 influenza pandemic, giving it a track record in humans, and is considered likely to return someday (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?).

Added to this mix, in 2008 the CDC’s EID Journal carried the following report on a newly emerging canine flu in Korea.

 

Transmission of Avian Influenza Virus (H3N2) to Dogs

Daesub Song, Bokyu Kang, Chulseung Lee, Kwonil Jung, Gunwoo Ha, Dongseok Kang, Seongjun Park, Bongkyun Park, and Jinsik Oh

Abstract

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.

 

In late 2012, in China: Avian-Origin Canine H3N2 Prevalence In Farmed Dogs, we saw a study that found more than 12% of farmed dogs tested in Guangdong province carried a strain of canine H3N2 similar to that seen in Korea.

 

During the 2009 H1N1 pandemic we saw reports of dogs infected, and in the middle of the last decade we saw several reports indicating that dogs were susceptible to the H5N1 bird flu virus (see Study: Dogs And H5N1).

Cats, too, were infected during the 2009 H1N1 pandemic (see Companion Animals And Novel H1N1 & EID Journal: Pandemic H1N1 Infection In Cats), and In 2011, it was announced that Korea’s canine H3N2 had jumped to cats (see Korea: Interspecies Transmission of Canine H3N2).

 

Previously we’d seen reports of cats infected with the H5N1 virus after consuming infected birds.  The following comes from a World Health Organization GAR report from 2006.

H5N1 avian influenza in domestic cats

28 February 2006

(EXCERPTS)

Several published studies have demonstrated H5N1 infection in large cats kept in captivity. In December 2003, two tigers and two leopards, fed on fresh chicken carcasses, died unexpectedly at a zoo in Thailand. Subsequent investigation identified H5N1 in tissue samples.

In February 2004, the virus was detected in a clouded leopard that died at a zoo near Bangkok. A white tiger died from infection with the virus at the same zoo in March 2004.

In October 2004, captive tigers fed on fresh chicken carcasses began dying in large numbers at a zoo in Thailand. Altogether 147 tigers out of 441 died of infection or were euthanized. Subsequent investigation determined that at least some tiger-to-tiger transmission of the virus occurred.

In 2006, Dr. C.A. Nidom demonstrated that of 500 cats he tested in and around Jakarta, 20% had antibodies for the bird flu virus. In 2007 the FAO warned that: Avian influenza in cats should be closely monitored, and in 2012 the OIE reported on Cats Infected With H5N1 in Israel, although so far no sustained virus transmission in cats or from cats to humans has been observed.

 

Contrary to the prevailing scientific opinion until the early 2000’s, dogs and cats are obviously both susceptible to a variety of influenza A viruses. All of which proves that you never know what you are apt to find until you actually start looking for it. 

 

Which brings us to a pair of recently published studies.  The first being on the virulence (or lack, thereof) of H5N1 in dogs and cats, and what that might portend as far as transmission is concerned.

 

Arch Virol. 2014 Nov 22. 

Greater virulence of highly pathogenic H5N1 influenza virus in cats than in dogs.

Kim HM¹, Park EH, Yum J, Kim HS, Seo SH.

Author information

Abstract

Highly pathogenic H5N1 influenza virus continues to infect animals and humans. We compared the infectivity and pathogenesis of H5N1 virus in domestic cats and dogs to find out which animal is more susceptible to H5N1 influenza virus. When cats and dogs were infected with the H5N1 virus, cats suffered from severe outcomes including death, whereas dogs did not show any mortality.

Viruses were shed in the nose and rectum of cats and in the nose of dogs. Viruses were detected in brain, lung, kidney, intestine, liver, and serum in the infected cats, but only in the lung in the infected dogs. Genes encoding inflammatory cytokines and chemokines, Toll-like receptors, and apoptotic factors were more highly expressed in the lungs of cats than in those of dogs.

Our results suggest that the intensive monitoring of dogs is necessary to prevent human infection by H5N1 influenza virus, since infected dogs may not show clear clinical signs, in contrast to infected cats.

An interesting result, considering that last spring  Korea Detected H5N8 Antibodies In asymptomatic Farm Dogs.

The second study, which appears in the December issue of the EID Journal, looks at the ability of cats to contract, and spread a contemporary strain of the equine/canine H3N8 virus.

 

Equine Influenza A(H3N8) Virus Infection in Cats

Shuo Su¹, Lifang Wang¹, Xinliang Fu, Shuyi He, Malin Hong, Pei Zhou, Alexander Lai , Gregory Gray, and Shoujun Li

Abstract

Interspecies transmission of equine influenza A(H3N8) virus has resulted in establishment of a canine influenza virus. To determine if something similar could happen with cats, we experimentally infected 14 cats with the equine influenza A(H3N8) virus. All showed clinical signs, shed virus, and transmitted the virus to a contact cohort.

Conclusions

That cats are susceptible to EIV by direct inoculation is not surprising because infection of cats with various influenza A viruses has been reported. Feline respiratory tract epithelial cells contain sialic acid α-2,3-galactose β-1,3-N-acetyl galactosamine (SA α2,3 gal) receptors for avian and equine influenza viruses and SA α2,6 gal receptors for mammalian influenza virus (13).

However, our finding of horizontal transmission of EIV among cats is significant. If transmission occurs outside the laboratory, and if the basic reproduction rate is higher than 1.0, then EIV could potentially establish itself and circulate in this new host species. Why it has not yet happened naturally, as it did for canine influenza virus (H3N8), remains to be determined. Possibilities include lower transmission efficiency, lower probability of horse–cat contact, less virus shedding in a laboratory, or feline behavior (less social contact than dogs).

 

These researchers repeated this experiment with an older strain of the equine H3N8 virus, and while some of the cats seroconverted, they all remained asymptomatic. Illustrating the variance of virulence one often finds between clades or strains of the same influenza A subtype.

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In just over a decade we’ve gone from believing that dogs and cats aren’t really susceptible to flu to viewing them as Potential `Mixing Vessels’ For Influenza. 

 

Last summer, in Canine H3N2 Reassortant With pH1N1 Matrix Gene, we looked at this precise scenario. At roughly the same time the American Society for Microbiology issued this warning:

 

Evolution of Equine Influenza Led to Canine Offshoot Which Could Mix With Human Influenza

WASHINGTON, DC – June 19, 2014 – Equine influenza viruses from the early 2000s can easily infect the respiratory tracts of dogs, while those from the 1960s are only barely able to, according to research published ahead of print in the Journal of Virology. The research also suggests that canine and human influenza viruses can mix, and generate new influenza viruses.

(Continue . . . )

 

Although  it’s true that pigs and birds are considered  far superior biological `flu factories’,  any jump of a novel flu virus to a new species is viewed with concern, because it affords the virus new opportunities to acquire host adaptations – or reassort with other viruses – and thereby increases its chances of becoming a human health threat.

While the future role of dogs and cats in the evolution of influenza is subject to debate, for now, your pet is at far greater risk of catching the flu from you, than you are from it (see Companion Animals & Reverse Zoonosis).

Research: Ferret H5N1 Infection Via Consumption Of Infected Chicken

Photo Credit Wikipedia

 

 

# 8704

 

Although we’ve seen numerous warnings from public health agencies about the dangers of consuming undercooked poultry products in those areas of Asia and the Middle East where H5N1 is endemic, most of the evidence for that risk has been anecdotal.   We’ve seen a relatively small number of human H5N1 infections where consumption of undercooked poultry, or raw duck blood pudding, was been strongly suspected as the route of infection. 

 

Poultry and eggs are considered safe if handled and cooked properly.  Consumption of raw blood pudding (duck or pig), a delicacy in Asia, is probably never a good idea as it carries other additional risks, including Strep Suis infection (see A Streptococcus suis Round Up).

.

 

In 2010, we saw a study (see H5N1 Can Replicate In Human Gut) that provided additional evidence that the bird flu virus can thrive in the human gastrointestinal system. Researchers found that Avian Influenza A(H5N1) Viruses Can Directly Infect and Replicate in Human Gut Tissues.

 

We’ve also seen numerous reports over the years of cats infected with the H5N1 virus after consuming infected birds.  The following comes from a World Health Organization GAR report from 2006.

H5N1 avian influenza in domestic cats

28 February 2006

(EXCERPTS)

Several published studies have demonstrated H5N1 infection in large cats kept in captivity. In December 2003, two tigers and two leopards, fed on fresh chicken carcasses, died unexpectedly at a zoo in Thailand. Subsequent investigation identified H5N1 in tissue samples.

In February 2004, the virus was detected in a clouded leopard that died at a zoo near Bangkok. A white tiger died from infection with the virus at the same zoo in March 2004.

In October 2004, captive tigers fed on fresh chicken carcasses began dying in large numbers at a zoo in Thailand. Altogether 147 tigers out of 441 died of infection or were euthanized. Subsequent investigation determined that at least some tiger-to-tiger transmission of the virus occurred.

 

In 2006, Dr. C.A. Nidom demonstrated that of 500 cats he tested in and around Jakarta, 20% had antibodies for the bird flu virus.  And in 2007 the FAO warned that: Avian influenza in cats should be closely monitored, although so far no sustained virus transmission in cats or from cats to humans has been observed.

 

Dogs are not exempt, as in 2006 the EID Journal published a Dispatch Fatal Avian Influenza A H5N1 in a Dog that documented a a fatal outcome following ingestion of an H5N1-infected duck in Thailand in 2004.

 

In 2011 we looked at a study that examined Gastrointestinal Bird Flu Infection In Cats, and as recently as 2012 the OIE reported on Cats Infected With H5N1 in Israel.

 

All of which brings us to a new short report that appears in Veterinary Research, that attempts to quantify the viral dose needed to infect ferrets through ingestion of infected meat.   First the link and abstract (the entire study is available), and an excerpt from the Discussion, then I’ll be back with a little more.

 

High doses of highly pathogenic avian influenza virus in chicken meat are required to infect ferrets

Kateri Bertran and David E Swayne

Author Affiliations

For all author emails, please log on.

Veterinary Research 2014, 45:60  doi:10.1186/1297-9716-45-60

Published: 3 June 2014

Abstract (provisional)

High pathogenicity avian influenza viruses (HPAIV) have caused fatal infections in mammals through consumption of infected bird carcasses or meat, but scarce information exists on the dose of virus required and the diversity of HPAIV subtypes involved. Ferrets were exposed to different HPAIV (H5 and H7 subtypes) through consumption of infected chicken meat.

The dose of virus needed to infect ferrets through consumption was much higher than via respiratory exposure and varied with the virus strain. In addition, H5N1 HPAIV produced higher titers in the meat of infected chickens and more easily infected ferrets than the H7N3 or H7N7 HPAIV.

The complete article is available as a provisional PDF. The fully formatted PDF and HTML versions are in production.

Discussion

In  conclusion,  relatively  high  concentrations  of  H5N1  HPAIV  are  required  to  produce infection  and  death  by  consumption  of  infected  meat  in  ferrets  as  compared  to  respiratory exposure.  Ingestion  of  HPAIV-infected  meat  can  produce  infection  that  primarily  involves  the respiratory tract but can also spread systemically depending on both the virus strain and virus dose received. Although human infections by HPAIV through direct oral contact have  been occasionally reported [12,13], airborne virus or contact with fomites is still considered the main route of exposure in human species [1].

 

Essentially researchers used 9 ferrets per virus tested, dividing them into three groups; low dose, medium dose, and high dose. They then compared morbidity, and mortality, seroconversion rates, and finally necropsy and histopathology test results to determine which viruses were able to infect via the oral consumption route, their effects, and how much of a viral load was required.

 

H5N1 viruses tended to replicate to higher titers in poultry meat than did the H7 viruses tested, and therefore were more infectious. 

 

Interestingly (but not surprisingly), there was a good deal of variability in the ferret outcomes between the two HPAI H5N1 strains (Mong/05 & VN/04) tested. None of the Mong/05 infected ferrets died, and most showed little or no signs of illness. Seven of nine seroconverted. Two of the VN/04 infected ferrets died, while two other seroconverted.

 

As this study illustrates, different clades of the H5N1 virus often demonstrate different degrees of virulence, something we looked at back in 2012 in Differences In Virulence Between Closely Related H5N1 Strains.

 

With the caveat that it is always a bit perilous to transpose animal study results to humans, this study supports the notion that consumption of improperly cooked avian-flu-infected poultry products could be reasonably assumed to pose a health risk.  

 

The good news, at least for ferrets, is that it takes a fairly large helping, and  the `right’ strain of virus, to prove fatal.

PHE: Transmission Of Bovine TB From Felines To Humans - UK

 

 

# 8410

 

Readers with good memories will recall that back in 2010 I wrote a blog called Badgers? We Don’t Need No Stinkin’ Badgers!, that looked at a controversial plan to cull badgers in the UK in an attempt to reduce the wildlife reservoir of Mycobacterium bovis which is the cause of tuberculosis in cattle (known as bovine TB).

 

M. bovis is also capable of infecting humans (mainly through unpasteurized milk), although famers in contact with infected cattle are at risk as well.

 

In fact, of the three type of Tuberculosis bacteria (Mycobacterium bovis, M. avium, and M. tuberculosis – the most prevalent strain in humans), M. bovis has the largest host range – being capable of infecting just about all warm-blooded vertebrates.

 

Last year, a study appeared in the CDC’s EID Journal that attempted to estimate the global burden of M. bovis infection in humans (see Zoonotic Mycobacterium bovis–induced Tuberculosis in Humans), and found that while the number was small (roughly 1 per 100,000 pop.) - it was not insignificant – particularly in areas of the world where unpasteurized milk is still widely consumed.

 

DEFRA calls Bovine TB one of the biggest challenges facing UK cattle industry, and cites the following key facts:

• 5.5 Million – total number of TB tests on cattle in England in 2011.
• 28,000 – approximate number of cattle slaughtered for TB control in England in 2012.
• 3,900 – approximate number of new TB incidents in 2012 (herds where at least one animal tests positive for bovine TB, when the herd had previously been TB free).
• 11.5% of cattle herds in England were under cattle movement restrictions at some point in 2011 (the 2012 statistics will be published once additional quality assurance checks have been completed).
• 23.6% of cattle herds in the South-West were under cattle movement restrictions at some point in 2011 (the 2012 statistics will be published once additional quality assurance checks have been completed).
• £500 million – the amount it has cost the taxpayer to control the disease in England in the last 10 years.
• £1 billion – estimated cost of TB control in England over the next decade without taking further action.
• £34,000 – the average cost of a TB breakdown on a farm, of which around £12,000 falls to the farmer.

 

While many farmers see badgers as the primary source of their bovine TB woes, and blame them for reintroducing the disease into their herds each year, conservation and animal rights groups strongly disagree, and argue that the badger is the victim here.

 

They maintain that cow-to-cow transmission is the primary route of infection, and that badgers usually get the disease from cattle – not the other way around.

 

Four years, and a pilot culling program later, and the controversy still reigns. Recent media coverage has run the gamut from TB strategy about much more than badger culling – Paterson -Farmers Guardian to MPs vote overwhelmingly to halt badger cull in England – The Guardian.

 

Adding a new dynamic to an already complex and contentious debate, yesterday Public Health England released a report on two rare human infections with M. bovis – both associated with an outbreak in cats – which likely became infected via contact (directly or indirectly) with badger setts (dens). 

 

The feline outbreak is described in a letter published in the BMJ’s Veterinary Journal called Mycobacterium bovis infection in cats by Nigel Gibbens, which prompted a full epidemiological investigation.  A brief excerpt:

 

BETWEEN December 2012 and March 2013, a veterinary practice in Newbury (west Berkshire) diagnosed nine cases of Mycobacterium bovis infection in domestic cats. In seven of those cases the diagnosis was confirmed by bacteriological culture. The nine affected cats belonged to different households and six of them resided within a 250 metre radius. The animals presented with mycobacterial disease of variable severity including anorexia, non-healing or discharging infected wounds, evidence of pneumonia and different degrees of lymphadenopathy. The latest information is that six of the cats have been euthanased or have died. The three surviving animals are undergoing treatment and are reported to be responding. At the time of writing, no new cases had been detected in local cats since March 2013.

 

PHE published the following press release on their website yesterday regarding the epidemiological investigation that turned up two probable cases where humans contracted M. bovis from cats.

 

Cases of TB in domestic cats and cat-to-human transmission: risk to public very low

Published 27 March 2014

Two people in England have developed tuberculosis after contact with a domestic cat infected with ‘Mycobacterium bovis’ (‘M. bovis’), Public Health England (PHE) and the Animal Health and Veterinary Laboratories Agency (AHVLA) have announced.’‘M. bovis’ is the bacterium that causes tuberculosis (TB) in cattle (bovine TB) and in other species.

Nine cases of ‘M. bovis’ infection in domestic cats in Berkshire and Hampshire were investigated by AHVLA and PHE during 2013. PHE offered TB screening to 39 people identified as having had contact with the infected cats as a precautionary measure. 24 contacts accepted screening. Following further investigations, a total of 2 cases of active TB and 2 cases of latent TB were identified. Latent TB means they had been exposed to TB at some point but they did not have active disease. Both cases of active TB disease have confirmed infection with ‘M. bovis’ and are responding to treatment.

There have been no further cases of TB in cats reported in Berkshire or Hampshire since March 2013. PHE has assessed the risk of transmission of ‘M. bovis’ from cats to humans as being very low.

Dr Dilys Morgan, head of gastrointestinal, emerging and zoonotic diseases department at PHE, said:

“It’s important to remember that this was a very unusual cluster of TB in domestic cats. ‘M. bovis’ is still uncommon in cats - it mainly affects livestock animals. These are the first documented cases of cat-to-human transmission, and so although PHE has assessed the risk of people catching this infection from infected cats as being very low, we are recommending that household and close contacts of cats with confirmed ‘M. bovis’ infection should be assessed and receive public health advice.”

The findings of the animal health aspects of this investigation are published in The Veterinary Record today, 27 March 2014.

 

Molecular analysis at AHVLA showed that ‘M. bovis’ isolated from the infected cats and the human cases with active TB infection were indistinguishable, which indicates transmission of the bacterium from an infected cat. In the other cases of latent TB infection, it is not possible to confirm whether these were caused by ‘M. bovis’ or the source of their exposure.

 

Transmission of ‘M. bovis’ from infected animals to humans can occur by inhaling or ingesting bacteria shed by the animal or through contamination of unprotected cuts in the skin while handling infected animals or their carcasses.

 

Professor Noel Smith, Head of the Bovine TB Genotyping Group at AHVLA, said:

“Testing of nearby herds revealed a small number of infected cattle with the same strain of ‘M. bovis’ as the cats. However, direct contact of the cats with these cattle was unlikely considering their roaming ranges. The most likely source of infection is infected wildlife, but cat-to-cat transmission cannot be ruled out.”

Cattle herds with confirmed cases of bovine TB in the area have all been placed under movement restrictions to prevent the spread of disease.

 

Local human and animal health professionals are remaining vigilant for the occurrence of any further cases of disease caused by ‘M. bovis’ in humans, cats or any other pet and livestock animal species.

(Continue . . . )

 

The PHE also released a HAIRS Risk Assessment, where they characterized the risk to public health as:

 

A Very low risk of transmission of M. bovis from cats to humans.

 

Although the risk of acquiring TB from a domestic cat in the UK is exceedingly low, and even less likely here in the United States, this report illustrates how animals – both wild and domestic – can carry and transmit zoonotic infections to humans.

 

This intersection of man and other species, and their sharing of viruses (zoonotic transmission), has increasingly been recognized as a driving factor in emerging infectious diseases, and even the creation of pandemics.

 

The age of emerging infectious diseases in humans really began in earnest about 10,000 years ago when humans began to domesticate – and live in close proximity to – other animals (see The Third Epidemiological Transition).

   

Measles probably evolved from canine distemper and/or the Rinderpest virus of cattle. Tuberculosis, which now infects 1/3rd of humanity, likely jumped from domesticated goats and cattle.  And influenza’s all seem to have an origin in waterfowl.

 

Other zoonotic nasties include Babesiosis, Borrelia (Lyme), Nipah, Hendra, Malaria, Hantavirus, Ebola, Leptospirosis, Q-Fever, bird flu . . . the list is long and growing.

 

Roughly 70% of the infectious diseases that afflict man today are believed to have begun in some other species, and new ones (think MERS-CoV, H7N9, H5N1, SFTS, etc. ) continue to show up each year. We live in an amazingly complex and interconnected world, where what happens in a live poultry market in China, a camel stable in Saudi Arabia, or a pig farm in Mexico can ultimately impact the health of people around the world.

 

So we watch these spillovers of diseases from animals to humans – no matter how rare, or small they may be – with considerable interest.

Interspecies Transmission Of Canine H3N2 In The Laboratory

 

 

# 6343

 

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.

 

In 2008 the CDC’s EID Journal carried the following report on this newly emerging canine flu.

 

Transmission of Avian Influenza Virus (H3N2) to Dogs

Daesub Song, Bokyu Kang, Chulseung Lee, Kwonil Jung, Gunwoo Ha, Dongseok Kang, Seongjun Park, Bongkyun Park, and Jinsik Oh

Abstract

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.

 

Inter- and intraspecies transmission of canine influenza virus (H3N2) in dogs, cats, and 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

DOI: 10.1111/j.1750-2659.2012.00379.x

ABSTRACT (excerpts)

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.

(Continue . . . )

 

CIDRAP NEWS published some details not available in the abstract above in their flu news roundup last night.

 

Follow the link to read:

Study: Canine influenza H3N2 can spread to cats

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

abstract

 

 

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. 

Israel: Cats Infected With H5N1

 

 

UPDATED:  The Jerusalem Post is now carrying this story with advice to their readers to avoid contract with stray cats in the area.

 

Three stray cats die of avian flu in Eilat

By JUDY SIEGEL-ITZKOVICH

LAST UPDATED: 03/15/2012 18:58

Three stray cats found by the Veterinary Service and Health Ministry inspectors at Shalva and Holit in southwest Israel were confirmed as having died from eating poultry infected with avian flu.

 

 # 6225

 

 

Last week Israel reported to the OIE a couple of bird flu outbreaks (H5N1) in turkeys in Hadarom.  Israel has seen limited outbreaks in poultry in the past, and so this was not exactly a huge story. 

But today the story takes a bit of a turn as we learn from a fresh OIE report that several cats have died after ingesting infected turkey carcasses (a hat tip goes to Giuseppe Michieli on FluTrackers for posting this report.)

 

While we’ve seen reports of cats infected with the H5N1 virus in the past, it is a fairly uncommon occurrence, particularly over the past few years.

 

First some details from today’s report, then I’ll return with more.

 

 

H5N1 was diagnosed in turkeys on 8 March 2012. On 9 March 2012, just before the culling of the birds, cats were seen eating carcasses. On 14 March 2012, 4 cats were found dead around the affected pen and some showed clinical signs such as respiratory signs and weakness. On 15 March 2012, the authorities succeeded to catch 16 cats roaming around the infected pen and euthanized them.

 

 

We’ve a number of reports over the years of cats infected with the H5N1 virus after consuming infected meat, the most famous being the deaths of scores of tigers kept in zoos in Thailand.

 

The following comes from a World Health Organization GAR report from 2006.

 

H5N1 avian influenza in domestic cats

28 February 2006

(EXCERPTS)

Several published studies have demonstrated H5N1 infection in large cats kept in captivity. In December 2003, two tigers and two leopards, fed on fresh chicken carcasses, died unexpectedly at a zoo in Thailand. Subsequent investigation identified H5N1 in tissue samples.

 

In February 2004, the virus was detected in a clouded leopard that died at a zoo near Bangkok. A white tiger died from infection with the virus at the same zoo in March 2004.

 

In October 2004, captive tigers fed on fresh chicken carcasses began dying in large numbers at a zoo in Thailand. Altogether 147 tigers out of 441 died of infection or were euthanized. Subsequent investigation determined that at least some tiger-to-tiger transmission of the virus occurred.

 

In 2006, Dr. C.A. Nidom demonstrated that of 500 cats he tested in and around Jakarta, 20% had antibodies for the bird flu virus.  

 

In 2007 the FAO warned that:

 

Avian influenza in cats should be closely monitored

So far no sustained virus transmission in cats or from cats to humans

 

For an overview of a number of other cases involving cats, see Apparently They Didn't Get The Memo.  But reports such as these have become less common over the past couple of years.

 

Last November we saw a study in the Journal of Virology that looked at an unusual route of infection  - and resultant pathogenesis – of the H5N1 virus in cats.

 

The study is called:

Marked endotheliotropism of highly pathogenic avian influenza virus H5N1 following intestinal inoculation in cats.

November 2011, doi: 10.1128/​JVI.06375-11

Reperant LA, van de Bildt MW, van Amerongen G, Leijten LM, Watson S, Palser A, Kellam P, Eissens AC, Frijlink HW, Osterhaus AD, Kuiken T.

 

Endotheliotropism is simply a 12-dollar word meaning an affinity for endothelial cells which are the cells that line the interior surface of blood vessels throughout the body.

 

From the abstract (the entire study is behind a pay wall), we learn that researchers gave cats enteric coated capsules containing H5N1 infected chicken liver in order to deliver the virus directly to the intestine.

 

(EXCERPT)

Intestinal inoculation of HPAIV H5N1 resulted in fatal systemic disease. The spread of HPAIV H5N1 from the lumen of the intestine to other organs took place via the blood and lymphatic vascular systems but not via neuronal transmission.

 

Remarkably, the systemic spread of the virus via the vascular system was associated with massive infection of endothelial and lymphendothelial cells, resulting in widespread hemorrhages.

 

As the abstract points out, this resulted in a disease process similar to what is seen in terrestrial poultry, and differs greatly from the pathogenesis normally seen from respiratory tract infection.

 

The authors conclude that:

 

The marked endotheliotropism of the virus following intestinal inoculation indicates that the pathogenesis of systemic influenza virus infection in mammals may differ according to the portal of entry.

 

The surprise here isn’t that cats (and other mammals) can acquire the H5N1 virus via a non-respiratory route (we’ve known that for some time), it is the discovery of the manner in which the virus spread systemically; via massive infection of endothelial and lymph endothelial cells.

 

Another example of how H5N1 behaves in unexpected ways, and further evidence that we are just scratching the surface in our exploration and understanding of this remarkable virus.

Gastrointestinal Bird Flu Infection In Cats

 

 

 

# 5969  

 

 

An intriguing study from the Journal of Virology this morning that looks at an unusual route of infection  - and resultant pathogenesis – of the H5N1 virus in cats (My thanks to Tetano on FluTrackers for posting this link).

 

The study is called:

 

Marked endotheliotropism of highly pathogenic avian influenza virus H5N1 following intestinal inoculation in cats.

November 2011, doi: 10.1128/​JVI.06375-11

Reperant LA, van de Bildt MW, van Amerongen G, Leijten LM, Watson S, Palser A, Kellam P, Eissens AC, Frijlink HW, Osterhaus AD, Kuiken T.

 

 

Endotheliotropism is simply a 12-dollar word meaning an affinity for endothelial cells which are the cells that line the interior surface of blood vessels throughout the body.

 

 

Photo Credit – Wikipedia

 

From the abstract (the entire study is behind a pay wall), we learn that researchers gave cats enteric coated capsules containing H5N1 infected chicken liver in order to deliver the virus directly to the intestine.

 

(EXCERPT)

Intestinal inoculation of HPAIV H5N1 resulted in fatal systemic disease. The spread of HPAIV H5N1 from the lumen of the intestine to other organs took place via the blood and lymphatic vascular systems but not via neuronal transmission.

 

Remarkably, the systemic spread of the virus via the vascular system was associated with massive infection of endothelial and lymphendothelial cells, resulting in widespread hemorrhages.

 

As the abstract points out, this resulted in a disease process similar to what is seen in terrestrial poultry, and differs greatly from the pathogenesis normally seen from respiratory tract infection.

 

The authors conclude that:

 

The marked endotheliotropism of the virus following intestinal inoculation indicates that the pathogenesis of systemic influenza virus infection in mammals may differ according to the portal of entry.

 

 

The surprise here isn’t that cats (and other mammals) can acquire the H5N1 virus via a non-respiratory route (we’ve known that for some time), it is the discovery of the manner in which the virus spread systemically; via massive infection of endothelial and lymph endothelial cells.

 

While anything that betters our understanding of the H5N1 virus is a good thing, this discovery may eventually have practical applications as well. 

 

Should an outbreak occur, gastrointestinal H5N1 infection (with its atypical pathogenesis) may require a different treatment regimen than is currently used with a respiratory infections.

 

An oral route of infection from the H5N1 virus has been suggested over the years, with several human cases being linked to the consumption of infected poultry.

 

One of the earliest indications that H5N1 could bind and flourish in the human gastrointestinal tract comes from this study involving the deaths of a brother and sister in Vietnam in 2004.

 

Fatal avian influenza A (H5N1) in a child presenting with diarrhea followed by coma.

de Jong MD, Bach VC, Phan TQ, Vo MH, Tran TT, Nguyen BH, Beld M, Le TP, Truong HK, Nguyen VV, Tran TH, Do QH, Farrar J.

 

 

In June of 2007, we got a report (see Atypical Presentations of H5N1)  out of Indonesia, of a child infected with H5N1 but that presented without respiratory symptoms.

 

A year later, in a large review of Chinese bird flu patients (see Clinical Case Review Of 26 Chinese H5N1 Patients), we find several mentions of gastrointestinal involvement as well.

 

Diarrhea was present in only two H5N1 cases at admission, but developed in a quarter of cases during hospitalization. Diarrhea was a common presenting symptom among H5N1 cases in Vietnam  and Thailand , but was reported infrequently among cases in Hong Kong SAR, China and Indonesia.

 

H5N1 virus and viral RNA have been detected in feces and intestines of human H5N1 cases. Whether the gastrointestinal tract is a primary site for H5N1 virus infection is currently unknown.

 

In 2010, we saw a study (see H5N1 Can Replicate In Human Gut) that provided even more evidence that the bird flu virus can thrive in the human gastrointestinal system.

 

We’ve also seen numerous reports over the years of cats infected with the H5N1 virus after consuming infected birds.  The following comes from a World Health Organization GAR report from 2006.

 

 

H5N1 avian influenza in domestic cats

28 February 2006

(EXCERPTS)

Several published studies have demonstrated H5N1 infection in large cats kept in captivity. In December 2003, two tigers and two leopards, fed on fresh chicken carcasses, died unexpectedly at a zoo in Thailand. Subsequent investigation identified H5N1 in tissue samples.

 

In February 2004, the virus was detected in a clouded leopard that died at a zoo near Bangkok. A white tiger died from infection with the virus at the same zoo in March 2004.

 

In October 2004, captive tigers fed on fresh chicken carcasses began dying in large numbers at a zoo in Thailand. Altogether 147 tigers out of 441 died of infection or were euthanized. Subsequent investigation determined that at least some tiger-to-tiger transmission of the virus occurred.

 

In 2006, Dr. C.A. Nidom demonstrated that of 500 cats he tested in and around Jakarta, 20% had antibodies for the bird flu virus.  

 

In 2007 the FAO warned that:

 

Avian influenza in cats should be closely monitored

So far no sustained virus transmission in cats or from cats to humans

 

For an overview of a number of other cases involving cats, see Apparently They Didn't Get The Memo.

 

And it isn’t just the H5N1 virus which as shown some propensity for gastrointestinal involvement.

 

Seasonal A & B Influenza viruses, along with the 2009 H1N1 virus, have been looked at for exhibiting unusual gastrointestinal symptoms, albeit nowhere near as severe as described in today’s study.   

 

In January of 2010, in Influenza’s Gastrointestinal Connection, I wrote about a study that appeared in BMC Infectious Diseases, that looked at seasonal flu in pediatric patients. 

 

 

Influenza virus infection among pediatric patients reporting diarrhea and influenza-like illness

The detection of influenza viral RNA and viable influenza virus from stool suggests that influenza virus may be localized in the gastrointestinal tract of children, may be associated with pediatric diarrhea and may serve as a potential mode of transmission during seasonal and epidemic influenza outbreaks.

 

And lastly, during the 2009 pandemic, the CDC’s Interim guidance on Infection Control for the pandemic H1N1 Virus, warned:

 

Transmission of influenza through the air over longer distances, such as from one patient room to another, is thought not to occur. All respiratory secretions and bodily fluids, including diarrheal stools, of patients with 2009 H1N1 influenza are considered to be potentially infectious.

 

 

More evidence (as if we needed it) to show that influenza is a far more complex, and fascinating, virus than most people give it credit for.

Korea: Interspecies Transmission of Canine H3N2

 

 

 

# 5669

 

Many of the common illnesses we think of as `human’ diseases actually began in other species, and only later migrated to humans. The age of emerging infectious diseases in humans really began in earnest about 10,000 years ago when man began to domesticate – and live in close proximity to – other animals.   

 

• The scourge of Tuberculosis, which now infects 1/3rd of humanity, probably jumped to humans when man began to coral 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.

 

Yet despite these disease overlaps, viruses generally adapt to a fairly narrow range of species. 

 

Horse viruses generally attack equines, and not say, cats and dogs.   Cat viruses tend to attack felines, and not birds.  Bird viruses usually only infect avian species.

 

The species that a virus will infect is known as its host range.  And while usually limited, it isn't always the case.

 

Rabies is a good example of a virus that can infect an extraordinarily wide range of species.

 

 

 

We know that every once in awhile, viruses will suddenly jump to a new species. A couple of recent examples include:

 

The H5N1 bird flu virus, which has been unusually promiscuous: showing up in cats (including tigers), dogs, martens, civets, and of course humans. Researchers have successfully infected cattle with the H5N1 virus, along with ferrets and mice for testing.

 

H3N8 Canine influenza, which only showed up in dogs in 2004, had been known to infect horses for the past 40 years.

 

 

All of which serves as prelude to a report that appears in the latest edition of the Journal of General Virology, that finds a recently emerged canine H3N2 influenza virus common in Korea has now adapted to infect domestic cats.

 

 

Interspecies transmission of the canine influenza H3N2 virus to domestic cats in South Korea, 2010

D.S. Song, D.J. An, H.J. Moon, M.J. Yeom, H.Y. Jung, W.S. Jung, S.J. Park, H.K. Kim, S.Y. Han, J.S. Oh, B.K. Park, J.K. Kim, H. Poo, R.G. Webster, K. Jung and B.K. Kang

Abstract

In the last 4 years, incidences of endemic or epidemic respiratory diseases associated with canine influenza H3N2 virus in Asian dogs have been reported in countries such as South Korea and China. Canine species were considered to be the new natural hosts for this virus.

However, at the beginning of 2010, influenza-like respiratory signs, such as dyspnea, were also observed among cats as well as in dogs in an animal shelter located at Seoul, South Korea. The affected cats showed 100% morbidity and 40% mortality.

We were able to isolate a virus from the lung specimen of a dead cat that had suffered from the respiratory disease, in embryonated chicken eggs. The 8 viral genes isolated were almost identical to those of the canine influenza H3N2 virus suggesting interspecies transmission of canine influenza H3N2 virus to the cat.

Moreover, 3 domestic cats infected with intranasal canine/Korea/GCVP01/07 (H3N2) all showed elevated rectal temperatures, nasal virus shedding, and severe pulmonary lesions, such as suppurative bronchopneumonia.

Our study for the first time shows that cats are susceptible to canine influenza H3N2 infection, suggesting that cats may play an intermediate host role in transmitting the H3N2 virus among feline and canine species, which could lead to the endemic establishment of the virus in companion animals.

Such a scenario raises a public health concern, as the possibility of the emergence of new recombinant feline or canine influenza viruses in companion animals with the potential to act as zoonotic infection cannot be excluded.

 

 

The canine H3N2 virus only just appeared in Korea in 2007, and unlike the canine H3N8 virus seen in the United States, appears to have jumped directly from an avian source.

 

In 2008 the CDC’s EID Journal carried the following report on this newly emerging canine flu.

 

Transmission of Avian Influenza Virus (H3N2) to Dogs

Daesub Song, Bokyu Kang, Chulseung Lee, Kwonil Jung, Gunwoo Ha, Dongseok Kang, Seongjun Park, Bongkyun Park, and Jinsik Oh

Abstract

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.

 

 

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 EID study above point 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.

 

Companion animals, such as dogs and cats, are of particular concern because of how closely humans interact with them.

 

While pigs might be biologically better suited as a `mixing vessel’ for influenza (see The (Swine) Influenza Reassortment Puzzle), there are far more opportunities for transmission between humans and their pets.

 

In terms of their potential to spread rapidly among humans, and cause significant morbidity and mortality, few viruses can compete with influenza. As we saw in 2009, a new influenza virus can jump species and spread around the globe in a matter of months.

 

A recurring theme in this blog is that nature’s bio lab is open 24/7, and that it is constantly trying out new genetic combinations looking for an evolutionary advantage. 

 

And for a virus, jumping to a new, immunologically naive species is like hitting the jackpot; a fresh supply of hosts and an opportunity to adapt further.

 

Which is why we watch these species jumps with more than a passing interest.

Companion Animals And Novel H1N1

 

 

# 5315

 

 

Colorized transmission electron micrograph (TEM) of HN1 virus – Credit CDC PHIL) 

 

Unlike `normal’ strains of human-adapted seasonal influenza - which are thought to rarely (if ever) infect dogs, cats, and other companion animals - the 2009 H1N1 virus has been observed a number of times in pets over the past 18 months.

 

Given that relatively few companion animals get tested for the H1N1 virus, and the likelihood that some animals only experience mild or sub-clinical symptoms of infection, the true prevalence of H1N1 infection among household pets is unknown. 

 

Yesterday, another veterinary industry alert was issued by IDEXX Laboratories - a company that produces a veterinary influenza test kit - regarding the first known H1N1 infection of 2011 in a domestic cat.

 

First some excerpts from the press release, then I’ll be back with more on pets and influenza.

 

 

First confirmed 2011 case of H1N1 influenza virus infection reported in a domestic cat

February 14, 2011

One cat with severe respiratory disease from Wisconsin has tested positive for the H1N1 influenza virus with the IDEXX H1N1 Influenza Virus RealPCR™ Test.

 

Two cats from the same household presented to a veterinary emergency hospital in respiratory distress. The owners reported to have been suffering from the flu themselves at the time the cats developed severe respiratory signs.

 

After intensive supportive care that included ventilator support, the 6-year-old male domestic shorthair (DSH) was euthanized. The IDEXX Feline Upper Respiratory Disease (URD) RealPCR™ Panel was performed using fluid obtained at the time of intubation for ventilation and was positive for the H1N1 influenza virus. The second cat, a 10-year-old female DSH, originally responded to supportive therapy but relapsed and was euthanized 8 days after presentation.

 

An oropharyngeal swab was obtained at the time of euthanasia for testing, but it was negative for H1N1 influenza virus. Given the strong-positive quantitative real-time PCR result in the first cat, the H1N1 influenza virus is still the presumptive cause of respiratory disease in the second cat. The shedding period of influenza viruses is short, which may have been responsible for the negative PCR result.

(Continue . . .)

 

The AVMA (American Veterinary Medical Association), which represents 80,000 Veterinarians around the nation, understandably keeps track of these cases.

 

They also maintain several  FAQs on H1N1 and pets.

 

» Veterinarians 2009 H1N1 FAQs

» Pet owners 2009 H1N1 FAQs

» General 2009 H1N1 FAQs

» Pandemic preparedness for veterinarians

 

 

Over the past year or so, we’ve seen ample evidence of non-human infection by the novel H1N1 virus (e.g.  turkeys, swine, ferrets, dogs, cats . . . even a cheetah).

 

This influenza’s propensity to cross species has also been observed with the H5N1 bird flu virus as well.

 

A few past blogs on the unusually promiscuous nature of the swine H1N1 influenza strain include:

 

US: Dog Tests Positive For H1N1

US: Turkey Farm Reports H1N1

Study: H1N1 And Birds

Cat Got Your Virus?

 

Cats seem to be more severely affected than dogs, at least based on the limited number of cases detected. Of eleven known feline cases, only 4 have recovered.

 

Last October we saw a study (see  EID Journal: Pandemic H1N1 Infection In Cats) that looked at the pathogenesis of novel H1N1 in domestic felines.

 

Experimental Pandemic (H1N1) 2009 Virus Infection of Cats

DOI: 10.3201/eid1611.100845
van den Brand JMA, Stittelaar KJ, van Amerongen G, van de Bildt M, Leijten LL, Kuiken T, et al. Experimental pandemic (H1N1) 2009 virus infection of cats. Emerg Infect Dis. 2010 Nov; [Epub ahead of print]

Conclusions

Intratracheal infection of domestic cats with pandemic (H1N1) 2009 virus resulted in mild-to-moderate clinical signs and virus replication throughout the respiratory tract that caused diffuse alveolar damage.

 

Pathogenic changes in the respiratory tract in cats were similar to those that occur in humans, macaques, and ferrets (7,11–13). Seroconversion of sentinel cats indicated cat-to-cat transmission.

 

The full study runs about 4 pages, with heavy emphasis on the necropsy and histological examination of these laboratory cats several days post infection.

 

Those discomforted by such details might want to skip the full paper.

 

While usually producing less dramatic symptoms, cats infected with the pandemic H1N1 virus showed similar pathogenic processes to cats infected with the HPAI H5N1 bird flu virus.

 

None of this is to suggest that your pet presents a serious H1N1 infection risk to you or your family.  Quite the opposite, in fact.

 

Your pet is far more likely to contract the virus from  you or other members of your household.

 

But promiscuous flu viruses - those capable of expanding their host range to other species - are a bit more worrisome because they have more opportunities to mutate, reassort, or evolve.

 

So we watch for signs of species jumping of any influenza with considerable interest.

EID Journal: Pandemic H1N1 Infection In Cats

 

Note: Today is my last full day in St. Augustine, I’ll be back on the road home tomorrow. I expect to resume my full blogging schedule on Monday.

 

 

# 4953

 

Different viruses have an affinity for different types of cells.  That is why most viruses are selective as to what organ systems they attack, or even what species are susceptible.

 

This explains why a virus might affect a dog, or a cat, or a bird, yet not affect humans.  This species selectivity is known as a `host range'.

 

Most viruses generally have a fairly narrow host range (there are exceptions, of course.  Like rabies).

 

One of the surprises coming out of the emergence of the 2009 H1N1 pandemic virus was its ability to infect wide range of species.

 

This wasn’t completely unprecedented with flu viruses, since we’ve seen this kind of pattern with the H5N1 bird flu  – but it is unusual for a `humanized’ influenza virus.

 

Cats, which normally are not susceptible to human influenza viruses, were reportedly stricken in a number of households (see  H1N1 Infected Cat Dies In Oregon).

 

Which serves as prelude to a study that appears ahead-of-print in the CDC’s EID Journal titled:

 

Experimental Pandemic (H1N1) 2009 Virus Infection of Cats 

DOI: 10.3201/eid1611.100845
van den Brand JMA, Stittelaar KJ, van Amerongen G, van de Bildt M, Leijten LL, Kuiken T, et al. Experimental pandemic (H1N1) 2009 virus infection of cats. Emerg Infect Dis. 2010 Nov; [Epub ahead of print]

Conclusions

Intratracheal infection of domestic cats with pandemic (H1N1) 2009 virus resulted in mild-to-moderate clinical signs and virus replication throughout the respiratory tract that caused diffuse alveolar damage.

 

Pathogenic changes in the respiratory tract in cats were similar to those that occur in humans, macaques, and ferrets (7,11–13). Seroconversion of sentinel cats indicated cat-to-cat transmission.

 

 

The full study runs about 4 pages, with heavy emphasis on the necropsy and histological examination of these laboratory cats several days post infection.

 

Those discomforted by such details might want to skip the full paper.

 

While producing less dramatic symptoms, cats infected with the pandemic H1N1 virus showed similar pathogenic processes to cats infected with the HPAI H5N1 bird flu virus.

 

Again, from the study:

 

Histopathologic and immunohistochemical findings in lungs of cats infected with these viruses coincided, which indicated a similar pathogenetic process and increased severity in cats infected with HPAI virus (H5N1).

However, in contrast to HPAI virus (H5N1), pandemic(H1N1) 2009 virus does not cause extrapulmonary lesions in infected cats.

 

Promiscuous viruses - those capable of expanding their host range - are a bit more worrisome because they have more opportunities to mutate, reassort, or evolve. 

 

And the more diverse their host range, the better the chance that the virus can find a way to  survive long term.

 

We’ve seen reports of swine, ferrets, turkeys, cats, and dogs infected with H1N1 virus over the past year, and similar reports for the H5N1 avian flu over the past decade as well.

 

A few essays on these include:

 

Mixing Vessels For Influenza

US: Dog Tests Positive For H1N1

US: Turkey Farm Reports H1N1

Cat Got Your Virus?

 

While none of this necessarily represents a clear and present danger to humans, it does illustrate how much more we have to learn about how influenza viruses work.

China Reports 2 Dogs With H1N1

 

 

# 4091

 

A little over 2-weeks ago we saw a video report from CCTV (China Central Television) news that voiced concerns over the H1N1 virus species jumping to pigs, cats, and according to that report . . . even dogs (see China Worries Over Species Jumping H1N1).

 

Dogs are not normally thought of as able to contract `human flu’ – although if you blog about influenza long enough, you learn not to discount something simply because its never been seen before . . .

 

Cats, after all, we were not thought likely to be susceptible to the novel H1N1 virus  either . . .  until, that is, reports of infected cats began to come in a little over a month ago.

 

Followers of the avian influenza story, of course, know that dogs and cats have both been infected by the H5N1 virus.  

 

Dr. C.A. Nidom demonstrated in 2006 that of 500 cats he tested in and around Jakarta, 20% had antibodies for the bird flu virus.   For an overview of a number of other cases, see Apparently They Didn't Get The Memo.

 

We’ve not heard of dogs being infected by the H1N1 virus before, although there have been reports of dogs being infected by the H5N1 avian flu.   See also Study: Dogs Can Shed H5N1 Virus.

 

Of course, H5N1 is avian flu, with different receptor binding domains than human flu. 

 

Six months ago, many scientists would probably have opined that dogs could not catch this `human flu’.  With the recent discovery of the virus in cats, some veterinarians and scientists have modified that stance to it being `unlikely’ that dogs would be susceptible.

 

Those with a more cautious bent, however, have simply have stated that there’s been `no evidence of human-to-dog transmission of the H1N1 virus’.

 

Well . . . not until now, anyway.

 

Today, at least according to Chinese state run media, we’ve what appears to be confirmation of reports of dogs infected with the novel H1N1 virus, with this story (hat tip Treyfish on FluTrackers) from Xinhua news.

 

Which proves . . . when it comes to influenza, one is wise to never say never.

 

 

 

China urges intensified supervision on A/H1N1 flu in animals

 

www.chinaview.cn  2009-11-28 09:43:42

BEIJING, Nov. 28 (Xinhua) -- China's Ministry of Agriculture has called for intensified monitoring and investigation of A/H1N1 flu in animals after two samples from sick dogs were tested positive for the virus.

 

The veterinary clinic of College of Veterinary Medicine at the China Agricultural University reported Wednesday that two out of 52 samples from sick dogs were tested positive for A/H1N1 flu virus, the ministry said late Friday.

 

Analysis of genetic composition found the virus detected in the samples and those found on human A/H1N1 flu cases were 99 percent homologous, it said.

 

The ministry urged local authorities to further enhance prevention and control, intensify monitoring and investigation in animal cases of A/H1N1 flu and closely watch the virus mutation situation in animals.