EID Journal: Equine H3N8 In Mongolian Bactrian Camel

 

Bactrian Camel – Credit Wikipedia

 

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Mongolia is home to recurring epizootic outbreaks of Equine H3N8 – an avian influenza that jumped to horses about a half century ago, and to dogs a decade ago -  among their horse populations (see Isolation and characterization of H3N8 equine influenza A virus associated with the 2011 epizootic in Mongolia). 

 

These outbreaks, which occur roughly once a decade, not only impact the lives and economy of nomadic Mongolians, it has the potential of exposing other mammals to the virus.

 

While not as plentiful as horses, the Bactrian (two humped) camel is an important domesticated beast of burden for Mongolians, and as such is frequently exposed to both humans and horses.  It is also on the critically endangered list, and may even be extinct in the wild.

 

In the fall of 1979 a severe epizootic influenza broke out among Mongolian camels, which turned out to be a reassortant of the recently re-emerged (1977) H1N1 (aka `Russian flu’) virus, showing that this species of camels was susceptible to at least some strains of influenza.

 

Virology. 1993 Dec;197(2):558-63.

A reassortant H1N1 influenza A virus caused fatal epizootics among camels in Mongolia.

Yamnikova SS¹, Mandler J, Bekh-Ochir ZH, Dachtzeren P, Ludwig S, Lvov DK, Scholtissek C. 

Abstract

In the autumn of 1979 a severe influenza epizootic started among camels in Mongolia (Lvov et al., 1982; Viprosi Virusol. 27, 401-405.) Between 1980 and 1983 13 independent isolates of H1N1 viruses were obtained from diseased camels, which were virtually indistinguishable from the human A/USSR/90/77 strain by serological means. Two hundred and seventy-one samples of camel sera collected between 1978 and 1983 contained antibodies against the human A/USSR/90/77 isolate. After experimental infection of camels with some of these isolates, the animals developed similar symptoms as those found during natural infection: coughing, bronchitis, fever, discharge from nose and eyes. A genetic sequence analysis revealed that among the eight segments (genes) the PB1, HA, and NA genes were almost identical with allelic genes of the USSR/77 strain, and the PB2, PA, NP, M, and NS genes were almost identical with those of the A/PR/8/34 strain.

 

Today the EID Journal carries a report on the detection of the Equine H3N8 influenza virus in a Mongolian Bactrian camel, likely acquired through exposure to infected horses.  First the link and some excerpts from the study, after which I’ll have a bit more:

 

Volume 20, Number 12—December 2014

Dispatch

Equine Influenza A(H3N8) Virus Isolated from Bactrian Camel, Mongolia

Myagmarsukh Yondon, Batsukh Zayat, Martha I. Nelson, Gary L. Heil, Benjamin D. Anderson, Xudong Lin, Rebecca A. Halpin, Pamela P. McKenzie, Sarah K. White, David E. Wentworth, and Gregory C. Gray

ABSTRACT

Because little is known about the ecology of influenza viruses in camels, 460 nasal swab specimens were collected from healthy (no overt illness) Bactrian camels in Mongolia during 2012. One specimen was positive for influenza A virus (A/camel/Mongolia/335/2012[H3N8]), which is phylogenetically related to equine influenza A(H3N8) viruses and probably represents natural horse-to-camel transmission.

CONCLUSIONS

The phylogeny indicates that A/camel/Mongolia/335/2012 probably represents a relatively recent horse-to-camel transmission event. Without additional isolates from camels or corresponding epidemiologic data, and given the close genetic relationship between A/camel/Mongolia/335/2012 and related equine viruses, it is impossible to determine at this time whether the virus has been successfully transmitted from camel to camel.

In recent years, enhanced surveillance has detected influenza A viruses across a wider range of mammalian hosts, including horses, swine, dogs (14), seals (15), cats, and now camels, providing a more complete picture of the ecology of influenza A viruses beyond their presence in birds. How influenza A viruses successfully jump from 1 host species to another, and what the constraints on interspecies transmission are, remain key questions about influenza virus ecology and assessments of pandemic threats. Our findings highlight the need to further elucidate the ecology of influenza viruses and other pathogens in free-ranging camel populations.

 

As noted before, anytime an influenza virus jumps to a new host, we tend to take notice.  Influenza viruses as a rule are promiscuous, but until 2003 when it jumped to dogs, the H3N8 virus had only impacted birds and horses.

 

Last week, in Study: Dogs As Potential `Mixing Vessels’ For Influenza, we looked at a study that examined the susceptibility of canine tracheal cells to infection by canine, equine, and human influenza strains – including equine H3N8.

 

Any species that is susceptible to multiple, and diverse, flu strains has at least the potential to serve as a `mixing’ vessel for viral reassortment. Dogs, given their massive numbers and close contact with humans, are a far greater concern in this regard than Mongolian camels.

 

While the discovery of a single equine H3N8 virus among Bactrian camels may seem like an obscure, perhaps even insignificant bit of research, it reveals another piece of the influenza puzzle.

 

Learning how influenza viruses jump and adapt to new species – even among relatively small population of animals in a remote areas of the world – may very well lead to a better understanding of how the next pandemic (or epizootic) virus will emerge.

Western Australia’s Equine Mystery

 

Credit WA Horse Alert Brochure

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Overnight Crof picked up a report from ProMed Mail concerning Australia: Mysterious new horse disease may have been passed to humans with details provided by The Australian (full story behind a wall).

 

While still unidentified, the good news is that Hendra – a bat borne virus that occasionally infects horses (see Australia: Hendra Vaccine Hurdles) and has killed at least 4 people over the years – has been ruled out.

 

A quick look at Western Australia’s State Health Department website turned up nothing, but I was able to find the following statement (dated July 8th) on the WA Department of Agriculture & Food website.

 

Updated horse health information

The Department of Agriculture and Food is continuing to test samples to identify the cause of mouth papules (small, solid rounded lumps) in horses on three properties in the South-West. There have been horse or equipment movements identified as potential links between the affected properties.

 

The papules were reported by a private veterinarian attending to the horses. Testing has already ruled out the main virus of concern, vesicular stomatitis. Preliminary testing suggests the lumps might be a response to a viral infection. The department is continuing to work with the veterinary clinic involved to finalise a diagnosis.

 

The horses reported have mild signs and it is likely people examining normal healthy horses’ mouths may see small lumps that are not necessarily of concern. The black tongue reported on Facebook may be due to staining from treatment or feed and is not related to the condition.

 

The Department of Agriculture and Food reminds horse owners to contact their local veterinarian if they notice unusual signs in their horses.

 

There are no restrictions on horse movement in WA or on events. The department’s standard horse biosecurity recommendations are that only healthy horses should attend events and they should not share feed, water, or tack and equipment with other horses.

 

There have also been reports that some humans who have had contact with affected horses have developed similar lesions in their mouths, although they remain generally well. The Department of Health has been assisting with the investigation of these cases. At this stage, it is not clear if there is a relationship between the lesions reported in horses and people, and testing has not revealed a cause for the lesions in either horses or people.

 

The Department of Health advises that people handling affected horses should take general precautions, such as wearing disposable gloves and a face mask, and washing their hands well after contact with affected horses. If they are concerned about their health they should consult a general practitioner.

 

For more information about horse biosecurity, visit agric.wa.gov.au and search ‘horse alert’.

 

The earliest report I’ve been able to find on this outbreak was from June 26th, in the RWWA website.

 

Department of Agriculture and Food Horse Health Information

The Department of Agriculture and Food has taken samples to identify the cause of mouth papules (small solid rounded bumps) in horses on one property in the South West after being contacted by a private veterinarian attending to the horses.

 

Testing has already ruled out the main virus of concern, vesicular stomatitis, and further testing is underway to determine the cause of the papules.

 

The department reminds horse owners if they do notice unusual signs in their horses to contact their local veterinarian.

 

There are no restrictions on horse movement in WA. As generally recommended, horse owners should be mindful of horse biosecurity. Only take healthy horses to events and do not share feed, water, or tack and equipment with other horses.

 

While this may sound like a minor health concern (and it may very well turn out to be), Australia’s equine community is still reeling from a major outbreak of Equine Influenza in 2007, which infected 10,000 properties, and more than 76,000 horses.

 

Monetary loses were calculated at AUD$363 million ($100 million in direct response costs and $263 million in government ssistance to the horse industry) – Cite HORSE ALERT

 

For more on horse biosecurity concerns, you may be interested in the following 74 page brochure produced by various agencies of the Australian government.

 

 

And in a slightly related story, back in 2010 I posted a fascinating article by Morens and Taubenberger: A New Look At The Panzootic of 1872 where they looked back at a wave of (presumably) equine influenza that swept across North American, infecting much of the horse population from Canada to Mexico – and killing up to 10%.

 

While the symptoms of this equine disease appear to be relatively mild in both horses and humans – over the past 30 years an estimated 70% of all emerging infectious diseases have originated from other animal species (see Woolhouse and Gowtage-Sequeria EID Journal 2005).

 

Which is why anytime what is perceived to be an animal disease jumps to humans, we tend to pay close attention.

Morens and Taubenberger: A New Look At The Panzootic Of 1872

 

 

 

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One of the most fascinating events in relatively modern infectious disease history occurred in the fall of 1872, when a massive wave of (presumably) equine influenza swept across North American, infecting much of the horse population from Canada to Mexico – and killing up to 10%.

 

You’ll find an excellent history of this outbreak from Horsetalk.co.nz.

 

How equine flu brought the US to a standstill

A Boston fire wagon without its horses.

September 26, 2007

 

Australia's equine flu outbreak may have crippled the racing industry, but an 1872 outbreak in North America brought the entire US economy to a virtual standstill.

(Continue . . .)

 

 

This was at a time in history when horses were the primary means of transportation, and the economic effects of this months long epizootic were substantial, and some have suggested it contributed to the economic Panic of 1873 the following year.

 

Ian York author of the Mystery Rays blog wrote about this incident back in December of 2009 in a blog called Influenza before 1918, part II: 1872.  A brief excerpt:

 

Without horses, business slammed to a halt; the mail didn’t run, groceries didn’t reach the cities, crops weren’t harvested or transported.  After a few weeks, most of the horses recovered and business followed, but the epizootic swept across the country (intensely tracked by the newspapers of the day, warning each city in turn that it was going to be attacked), finally fizzling out the following summer in British Columbia.

 

Little remembered today, this was a huge story in 1972.  The assumption has been that this was sparked by some drift or shift in an already existing equine influenza.

 

But David Morens and Jeffrey K. Taubenberger of the NIH bring us tantalizing details of a concurrent outbreak of poultry deaths across the country, and that raises some interesting questions.

 

Without the ability to analyze and identify pathogens from that era, researchers are understandably hampered in their understanding of what exactly what transpired 140 years ago.  

 

But Taubenberger and Morens discuss a plausible scenario where a highly pathogenic avian virus may have jumped species and infected horses, pigs, deer, and in some cases, even humans.

 

My thanks to mixin on FluTrackers for posting this link.

 

Morens and Taubenberger (2010) An avian outbreak associated with panzootic equine influenza in 1872: an early example of highly pathogenic avian influenza? Influenza and Other Respiratory Viruses 4(6), 373–377.

Abstract

Background An explosive fatal epizootic in poultry, prairie chickens, turkeys, ducks and geese, occurred over much of the populated United States between 15 November and 15 December 1872. To our knowledge the scientific literature contains no mention of the nationwide 1872 poultry outbreak.

Objective To understand avian influenza in a historical context.

Results The epizootic progressed in temporal-geographic association with a well-reported panzootic of equine influenza that had begun in Canada during the last few days of September 1872. The 1872 avian epizootic was universally attributed at the time to equine influenza, a disease then of unknown etiology but widely believed to be caused by the same transmissible respiratory agent that caused human influenza.

Conclusions Another microbial agent could have caused the avian outbreak; however, its strong temporal and geographic association with the equine panzootic, and its clinical and epidemiologic features, are most consistent with highly pathogenic avian influenza. The avian epizootic could thus have been an early instance of highly pathogenic avian influenza.

 

 

Jeffrey  K. Taubenberger and David Morens are, of course,  familiar names to followers of influenza and virology.

 

Both are researchers at NIAID. Taubenberger, quite famously, was the first to sequence the the genome of the 1918 Spanish Flu virus while David Morens is a prominent medical historian and professor.

 

Both are extensively published, and have collaborated often in the past.

 

As this report is too good to try to summarize, I’ll simply suggest you follow this link and read it in its entirety.