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A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
In this update:
[1] OIE report
[2] Canadian Press report
[3] Veterinary Record report
******
[1] OIE report
Date: Thu 11 Jun 2009
Source: OIE, WAHID (World Animal Health Information Database), weekly
disease information 2009; 22(24)[edited]
Influenza A (H1N1), Canada
--------------------------
Information received on (and dated) 11 Jun 2009 from Dr Brian Evans,
Chief Veterinary Officer, 1400 Merivale Road, Tower 1, Canadian Food
Inspection Agency, Ottawa, Canada
Summary
Report type: follow-up report no. 1
Start date: 21 Apr 2009
Date of 1st confirmation of the event: 1 May 2009
Report date: 11 Jun 2009
Date submitted to OIE: 11 Jun 2009
Reason for notification: emerging disease
Morbidity: 25 percent
Mortality: 0 percent
Zoonotic impact: possible transmission of the novel [influenza A
(H1N1)] virus from humans to pigs [see item 2. - Mod.AS]
Causal agent: novel A/H1N1 2009 influenza virus
Serotype: other
This event pertains to the whole country
Outbreaks: there are no new outbreaks in this report
Epidemiology
Source of the outbreak(s) or origin of infection: possible
transmission from humans to pigs [but see item 2. - Mod.AS]
Epidemiological comments: on 5 May 2009, CFIA [Canadian Food
Inspection Agency] reported that the full sequence of the virus
detected in swine on an Alberta farm confirmed that the virus found
in the pigs was the same as the novel H1N1 influenza A virus causing
illness in humans around the world.
The CFIA developed a strategy/approach/plan to resolve the animal
health issues associated with this farm, in line with the public
health concerns. Public health and animal health authorities,
nationally and internationally, were engaged in discussion. All
groups and organizations supported the "controlled marketing with no
cull" approach, which the CFIA advocated.
Clinical signs of respiratory disease observed in the herd at the
beginning of the outbreak have resolved and hogs in all affected
subpopulations have since recovered. Crowding conditions in the barn
forced a limited cull of approximately 500 mature hogs to alleviate
animal welfare concerns and to allow a period of time to do testing
in the herd. The hogs were humanely destroyed and transported to a
rendering establishment. The rendered material was buried in landfill
due to concerns about negative public perception of incorporating it
into animal feeds.
PCR tests on samples collected on 14 and 25 May [2009] showed
evidence of continued virus presence but at a low prevalence.
Isolating virus from these samples has not been successful, to date.
Research activities to determine the virulence of the novel H1N1
virus for animals and the associated risk have been undertaken. The
preliminary results indicate that the novel virus produces clinical
signs similar to the traditional influenza A viruses in swine.
The initial risk management decisions in this herd were precautionary
due to the lack of information to determine the risk to the swine and
human populations of North America. It was first suggested that a
virus negative test was needed to release movement restrictions.
However, although additional information provided insight to the
lower risk this virus would pose to the human and animal community,
it became difficult to modify the initial precautionary approach and
identify alternate criteria for the release of the quarantine. In
spite of clinical recovery and negative status of market weight
animals, market forces resulted in there being no slaughter facility
willing to receive the animals.
Due to an impending and further overcrowding situation in the barns
and an inability to market the animals following lifting of
restrictions, the owner petitioned the Alberta provincial government
for the destruction of the herd for economic reasons, to allow him to
exit the situation and resume operation with a replacement herd. The
culling of the herd was NOT an ordered destruction as the result of
animal or human disease considerations.
The quarantine will be lifted when appropriate cleaning and
disinfection measures have been completed on the infected premises.
The trace out/trace in investigation is complete. No additional farms
at-risk were identified.
--
Communicated by:
ProMED-mail
******
[2] Canadian Press report
Date: Sun 14 Jun 2009
Source: Edmonton Sun, The Canadian Press report [edited]
Blood tests provide information in pig farm swine flu case
----------------------------------------------------------
Officials have ruled out the prime suspect in the mystery over how a
herd of Alberta pigs was infected with the new swine flu virus
sweeping the globe.
A spokesperson for Alberta Health and Wellness says blood tests have
shown that a carpenter who worked for half a day on the farm before
heading home with flu-like illness did not introduce the virus to the
herd.
"We've determined it wasn't the carpenter," says spokesperson Howard May.
The workman declined to be interviewed about the findings. Previously
he'd said he did not believe he had infected the pigs, which were
raised on a farm near Rocky Mountain House.
[The carpenter] had just returned from a trip to Mexico when he went
to do a job at the farm on 14 Apr 2009. At that point the new H1N1
virus was already circulating in parts of the Mexico, but the world
was not yet aware a new flu virus was on the move.
The World Health Organization declared Thursday [11 Jun 2009] that
the new virus has triggered a pandemic, the 1st in 41 years.
May says provincial health officials are starting to believe they may
never find out how the virus made its way into the herd, the only
pigs anywhere in the world to have tested positive for the new virus
to this point.
"Since serological (blood) tests indicated the carpenter had not had
H1N1, someone else must have brought it in, but it is unlikely we
will ever be able to pinpoint exactly who," says May.
Officials had earlier said several members of the family that owned
the farm were sick a couple of days before [the carpenter] worked
there briefly.
Others fell ill after the pigs started to display signs of being
sick, leading authorities to suggest the virus may have gone from a
person to pigs and back to people. Nasal swabs taken from people on
the farm tested negative, but blood samples were taken to look for
antibodies to the virus.
Whether that work is completed and what the tests showed if it is,
hasn't been made public.
Recently the farmer who owned the herd announced he had destroyed his
pigs, because he could not sell the animals. The farm had been under
quarantine since late April [2009], when the outbreak first came to
the attention of the Canadian Food Inspection Agency [CFIA].
Sporadic tests continued to find evidence of possible ongoing
circulation of virus in the herd, says Dr Jim Clark, the national
manager for disease control for CFIA's animal health division.
Over the course of the weeks of quarantine, testing found diminishing
but still present viral DNA, which may or may not have meant
infectious viruses were still spreading among the pigs, Clark says.
He says the CFIA's lab in Winnipeg was only able to isolate live
viruses from the pigs when they were sampled at the beginning of the
investigation. Genetic sequencing of those viruses showed they are
virtually identical to the swine flu viruses circulating in humans.
Clark says CFIA would like to be able to determine how the pigs got
infected. But he says the agency isn't getting much co-operation from
human health counterparts responsible for testing the people involved.
"So far we haven't been able to get a whole lot of information from
them," he says, adding that while he's not sure why that is, privacy
concerns may play a role.
"There's a need to know from a scientific perspective, to try and I
guess to get a complete understanding of the epidemiology behind
this, but at the same time not wanting to put this (farm) family
under any more duress than they've already suffered."
Clark says he expects there will be other opportunities to learn
about how this virus behaves when it gets into pig populations. With
continued spread around the world, he suggests, "it's invariably
going to result in the exposure of pigs in other countries and in
other places."
But whether farmers will admit to it is another issue. The family who
owned the Alberta herd has reportedly paid a heavy price, financially
and personally. Pork sales are down, even though health officials
have repeatedly stressed people can't get swine flu from eating pork.
Though the CFIA has asked swine producers and veterinarians to be on
the lookout for possible infection in herds and to submit any unusual
flu viruses for further testing, "very little" is coming forward,
Clark admits.
"As soon as there's a disease outbreak, everybody gets real nervous
about what might be happening," he says.
The lengthy quarantining of the Alberta farm -- and the unfortunate
outcome -- may discourage farmers from reporting flu-like symptoms in
their pigs. There are a variety of influenza virus subtypes that
infect pigs and outbreaks, while common, are not a long-term threat
to the health of pigs.
"I think right now the production community is looking and saying
'OK, when you can tell us what you specifically want to do about the
situation, then we might be in a situation to want to submit samples
to find out what's going on,'" says Clark, who admits he has some
sympathy for that position.
"From a purely scientific perspective, I'd love all the samples in
the world to be coming in and get as much background information as
we can about where this virus may currently be occurring anywhere in
the swine population," he says.
"On the practical side, without having a clearly defined policy that
is able to get us out of the situation as quickly as possible and
define all the risk factors, I'm saying 'Well, maybe I don't really
want to know about too many things that are going on right now until
we can get more definitive information about what we need to be
concerned about.'"
[Byline: Helen Branswell]
--
Communicated by:
ProMED-mail Rapporteur Mary Marshall
******
[3] Veterinary Record report
Date: Sat 13 Jun 2009
Source: The Veterinary Record 2009 164: 760-1; letters [abridged
Mod.AS, edited]
(requires paid subscription)
Influenza A (H1N1) infection in pigs
------------------------------------
[From the letter above to Vet Rec, we present a copy of the
concluding, results passage. For the full text, in particular the
details of the experimental design and performance, subscribers are
referred to the URL above. Preliminary data were already included in
ProMED-mail postings 20090605.2088 and 20090604.2067. - Mod.AS]
Results of our preliminary analyses of the clinical, pathological,
shedding, and transmission data from the 1st 14 days of the study
have shown that pigs are susceptible to infection with influenza A
(H1N1) virus, which results in the induction of detectable levels of
clinical disease, virus shedding, and respiratory tract pathology in
an experimental setting. Furthermore, while variations in the range,
pattern and severity of clinical signs and morbidity were observed
between individuals and infected groups, these remained typical of
influenza A infections in pigs.
Importantly, mortality was not a feature, and infected animals were
able to transmit the virus to naive contact pigs successively for at
least 3 cycles of transmission, suggesting the virus could become
established in susceptible pig populations if introduced, with
consequent impacts. To date, reverse zoonosis has been reported to
have occurred naturally on one occasion in Canada (OIE 2009) [but see
item 2 above and commentary further. - Mod.AS], and we have now
demonstrated the potential for this phenomenon experimentally.
It is also important to note that the observed levels of morbidity
and mortality in a field setting may differ depending on a number of
factors, including the age of the pig, immune status to endemic swine
influenza viruses and, in particular, the role of other intercurrent
disease and/or pig husbandry and management factors that could result
in differing clinical and economic impacts to the pig industry.
A key aim of this study is the timely provision and dissemination of
critical data relating to the outcomes of infection with this novel
influenza A H1N1 virus in pigs to interested parties, including
veterinary surgeons, industry, and other stakeholders, and to also
provide a robust scientific evidence base to inform veterinary and
public health risk assessments and decision makers.
Further information and details relating to these preliminary
analyses can be found on the VLA [Veterinary Laboratories Agency]
website at
In addition, over the coming weeks and months further work and
analyses relating to this study are planned, and will be conducted by
all members of this EU study consortium. Updates will continue to be
provided through a variety of media, including websites (European
Commission, DG SANCO [Health and Consumer Protection Directorate
General of the European Commission,
VLA, Defra), and peer-reviewed and other publications.
References
----------
1. Irvine RM, Brown IH (2009): Novel H1N1 influenza in people: global
spread from an animal source? Veterinary Record 164, 577-8 [available
from
2. OIE (2009) World Organisation for Animal Health, WAHID Weekly
Disease Information, 22(19), 7 May 2009 [A/H1N1 influenza, Canada:
immediate notification
Accessed 28 May 2009
[Byline:
- Sharon M Brookes, Richard M Irvine, Alejandro Nunez, Derek
Clifford, Steve Essen, Ian H Brown, Community Reference Laboratory
for Avian Influenza and Newcastle Disease, VLA - Weybridge, New Haw,
Addlestone, Surrey KT15 3NB, United Kingdom
- Kristien Van Reeth, University of Ghent, 9820 Merelbeke, Belgium
- Gaelle Kuntz-Simon, Agence Francaise de Securite Sanitaire des
Aliments, LERAPP, Zoopole Les Croix, BP 53, 22440 Ploufragan, France
- Willie Loeffen, Central Veterinary Institute, Lelystad, PO Box 65
8200 AB Lelystad, The Netherlands
- Emanuela Foni, Istituto Zooprofilattico Sperimentale della
Lombardia e dell'Emilia Romagna, Sezione di Parma, 43100 Parma, Italy
- Lars Larsen, National Veterinary Institute, Technical University of
Denmark, 1790 Copenhagen V, Denmark
- Mikhail Matrosovich, Institute of Virology, Philipps University,
35043 Marburg, Germany
- Michel Bublot, Merial, 69007 Lyon, France
- Jaime Maldonado, Laboratorios HIPRA, 17170 Amer Girona, Spain
- Martin Beer, Friedrich-Loeffler-Institute, Federal Research
Institute for Animal Health, 17493 Greifswald-Insel Riems, Germany
- Giovanni Cattoli, Istituto Zooprofilattico Sperimentale Padova,
35020 Legnaro, Padova, Italy]
--
Communicated by:
Shamsudeed Fagbo
[The initial report from the Canadian animal-health authorities about
the event on the Alberta pig farm indicated that the transmission of
the novel A (H1N1) influenza virus from humans to pigs was
"possible". This, justifiably cautious, notification was based upon
circumstantial evidence and the identification of the novel A (H1N1)
influenza virus in the pigs; results from the person involved --
whose testing was addressed by a separate State agency -- were
pending. The current information, saying that the said person (a
carpenter returning from Mexico) has been eventually found
serologically negative for the novel A (H1N1) influenza virus, may
indicate that this was not a case of reverse zoonosis; alternatively,
if a human vector was involved, he/she has yet to have been
discovered. In any event, an official confirmation of the negative
test results of the carpenter is anticipated with interest.
This leaves us with 2 unavoidable questions: first, where did it come
from, and second, was this a solitary, single infection on a
Canadian/North American pig farm? A serosurvey on other pig farms
could provide the answer. As already apparent from the experimental
infection trials carried out in Europe and in Canada, the new virus
behaves in pigs like other strains of the common swine influenza
virus (SIV). The complexity and ramifications of such surveillance in
commercial pigs are described in item 2 above. - Mod.AS]
[see also:
Influenza A (H1N1): animal health (12) swine trial inf. 20090605.2088
Influenza A (H1N1): animal health (11) swine trial inf. 20090604.2067
Influenza A (H1N1): animal health (10) swine, Canada, cull 20090514.1813
Influenza A (H1N1): animal health (09), swine, Canada 20090513.1790
Influenza A (H1N1): animal health (07), swine, Canada, OIE 20090506.1691
Influenza A (H1N1): animal health (06), Canada, OIE 20090505.1683
Influenza A (H1N1): animal health (05), swine, Canada, FAO 20090505.1680
Influenza A (H1N1): animal health (04), infected swine, Canada 20090502.1653]
...................................arn/mj/lm
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