-------- Original Message --------
Subject: PRO/AH/EDR Influenza A (H1N1), "swine flu": animal health
Date: Tue, 28 Apr 2009 22:11:16 -0400 (EDT)
From: ProMED-mail promed@promed.isid.harvard.edu
Reply-To: promedNOREPLY@promed.isid.harvard.edu
To: promed-ahead-edr@promedmail.org
INFLUENZA A (H1N1), "SWINE FLU": ANIMAL HEALTH
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A ProMED-mail post
http://www.promedmail.orgProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org[1] Defra
[2] OIE
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[1] Defra
Date: Mon 27 Apr 2009
Source: Defra, Global Animal Health - International Disease
Monitoring. Preliminary Outbreak Assessment. Ref VITT 1200 H1N1
Influenza from humans [edited]
http://www.defra.gov.uk/animalh/diseases/monitoring/pdf/h1n1-090427.pdfRisk of introducing H1N1 "North American influenza" to the UK pig population
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Introduction
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There is concern that a new strain of human influenza A type H1N1 has
been circulating in Mexico since mid-March 2009. It has now spread
further within North America and is under investigation elsewhere. It
has been suggested that this strain of influenza virus may have
originated from pigs. However the virus has not been isolated from
pigs and there have been no reports of unusual disease in pig herds.
This report provides general information on swine influenza and trade
in pigs and pig products. Information is also provided on this
outbreak of influenza in humans. Unlike avian influenza, swine
influenza is not a notifiable or statutory disease and it is not
listed by the World Organisation for Animal Health (OIE). Pig keepers
and their veterinarians are therefore responsible for dealing with
outbreaks of influenza in pigs to safeguard the welfare and
productivity of their animals. Studies have shown that the previous
swine flu H1N1 strain is common throughout pig populations worldwide,
with around 25 percent of animals showing evidence of past exposure
to infection.
Swine influenza surveillance
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Swine influenza is a disease of pigs caused by a virus (influenza
virus). Influenza viruses exist as various types and the principal
type found in pigs is type A. The virus is present in all pig
producing countries, including the UK. Clinical signs of the disease
may include dullness, fever, coughing, and breathlessness with often
a rapid recovery. Swine influenza is often seen in combination with
other diseases (Defra, 2009).
When current strains of influenza infect pigs, the virus remains
within the respiratory tract and does not spread to other parts of
the body. Carcase meat should therefore not be contaminated with
virus and international standards for trade in animals and animal
products do not impose any restrictions in respect of influenza virus
infection for the protection of either animal or human health. There
is no obligation under international rules to carry out surveillance
for swine influenza so the level of information available varies
between different countries.
H1N1 and H3N2 swine flu viruses are endemic among pig populations in
many countries and something that the industry deals with routinely.
Outbreaks among pigs normally occur in colder weather months (late
fall and winter) and sometimes with the introduction of new pigs into
susceptible herds. In the US studies have shown that between 30 and
50 percent of the pig population has been exposed to H1N1 infection
at some time (CDC, 2009).
Mexico does not routinely report swine influenza so there is some
uncertainty regarding the situation in that country. Canada has
reported no signs of increased disease or mortality in Canadian
swine. The Canadian veterinary authorities are urging pig owners to
report any signs of respiratory disease in pigs (Canadian Food
Inspection Agency, 2009).
The UK and some other members of the European Union undertake
surveillance to help detect the presence of animal diseases,
including novel strains of influenza viruses, which are not normally
present in the country/EU. The tests used in the UK would be capable
of detecting this new variant of H1N1 but no cases have been
identified.
Trade in pigs and pig products from North America
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EU rules restrict trade from North America, not because of influenza
but in order to prevent the introduction of notifiable diseases in
animals. The following are permitted, provided that all the necessary
health conditions are met:
Country / live swine / fresh pig meat / cooked pig meat / porcine
semen and embryos
Mexico / no / no / no / no
USA / no / yes / yes / yes
Canada / yes / yes / yes / yes
Human influenza situation report
--------------------------------
Since March 2009, Mexico reported an increase in the number of cases
of severe respiratory infection in humans. Cases were reported from
24 out of 32 states in Mexico. In April [2009] the USA reported 2
cases of human influenza in California. Currently cases have been
confirmed in New York, California, Texas, Kansas, and Ohio. In Canada
there are 4 confirmed cases in children returning from holiday in
Mexico. Suspect cases are being investigated in Spain, New Zealand,
and the UK (PAHO, 2009).
Laboratory analysis of 2 virus isolates from cases in the USA
confirmed the presence of influenza virus type A strain H1N1. The
genetic sequence indicated recombination of North American swine
influenza, North American avian influenza, human influenza virus, and
Eurasian swine influenza. This is a new recombination of virus
strains, not previously isolated.
Reports of disease consistent with an epizootic of influenza have not
been reported in swine in these countries and there are no
indications that human disease has arisen from contact with pigs
(PAHO, 2009). Further investigations into the epidemiology of the
disease are underway in Mexico and the USA, which may help confirm
the source of infection. However all reports suggest the virus is
transmitting directly from human to human and there is no evidence
that pigs are involved in disease spread at present. If any evidence
arises of infection of pigs, we will re-assess the risk.
Conclusions
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We consider there is a negligible likelihood of introducing human
influenza strain H1N1 to the UK by the legal import of pigs or pig
products from North America. There is no evidence that meat or other
products would be contaminated with currently known strains of virus.
Current EU trade rules for live pigs and pig products are considered
appropriate to control this situation. Nevertheless, if future
surveillance indicates that pigs are involved in transmission of
disease or are reported to be infected, these rules can be
re-visited. Trade in live pigs is permitted from Canada and this
could possibly introduce a new strain of swine influenza virus to
European pig populations if Canadian pigs are infected. It is also
possible that an infectious human, returning to the UK, could
introduce a new strain to the pig population. In either case, pig
keepers are responsible for assuring themselves of the health status
of animals they buy. They are also responsible for implementing
biosecurity measures to safeguard their own livestock. However, there
is no obligation to report swine influenza so there is considerable
uncertainty as to the true situation in pigs. We will continue to
work with international organisations to understand whether there is
any unusual disease in pigs and whether any action to restrict trade
would be appropriate.
We will continue to review the situation.
References
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1. Canadian Food Inspection Agency (2009): Swine Influenza - Advice
for Veterinarians and Swine Producers. Available from
http://www.inspection.gc.ca/english/anima/disemala/swigri/swigrifse.shtml Accessed 27 Apr 2009.
2. CDC (2009): Key Facts about Swine Influenza (Swine Flu). Available from
http://www.cdc.gov/swineflu/key_facts.htm. Accessed 27 Apr 2009.
3. Defra (2009): Swine Influenza. Available from
http://www.defra.gov.uk/animalh/diseases/vetsurveillance/az_index.htm#s.
Accessed 27 Apr 2009
4. PAHO (2009): Influenza-like illness in the United States, Mexico.
Available from
http://new.paho.org/hq/index.php?option=com_content&task=view&id=1268&Itemid=327.
Accessed 27 Apr 2009.
--
Communicated by:
Sabine Zentis
Castleview Pedigree English Longhorns
Gut Laach
52385 Nideggen
Germany
http://www.cvlonghorns.decvlonghorns@aol.com
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[2] OIE
Date: Mon 27 Apr 2009
Source: OIE Press release [edited]
http://www.oie.int/eng/press/en_090427.htmA/H1N1 influenza like human illness in Mexico and the USA: OIE statement
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A virus circulating in Mexico and the USA and involving
person-to-person transmission appears to cause in some cases severe
disease in certain people infected by this virus. There is no
evidence that this virus is transmitted by food.
It is not a classical human influenza virus called seasonal
influenza, which causes every year millions of human cases of
influenza worldwide but a virus which includes in its characteristics
swine, avian, and human virus components.
Any current information in influenza-like animal disease in Mexico or
the USA could support a link between human cases and possible animal
cases including swine. The virus has not been isolated in animals to
date. Therefore, it is not justified to name this disease swine
influenza. In the past, many human influenza epidemics with animal
origin have been named using their geographic name, such as, Spanish
influenza or Asiatic influenza, thus it would be logical to call this
disease "North-American influenza."
Urgent scientific research must be started in order to know the
susceptibility of animals to this new virus, and if relevant to
implement biosecurity measures including possible vaccination to
protect susceptible animals. If this virus would be shown to cause
disease in animals, virus circulation could worsen the regional and
global situation for public health.
Currently, only findings related to the circulation of this virus in
pigs in zones of countries having human cases would justify trade
measures on the importation of pigs from these countries. The OIE
will continue its alert function and will publish in relation with
its members, reference laboratories, and collaborating centres all
appropriate information in real time.
OIE and FAO underline the great value of the influenza veterinary
laboratory network called OFFLU [joint OIE-FAO network of expertise
on avian influenza], in charge of the surveillance of the evolution
of influenza viruses in animals. There is a strong need to reinforce
this network whose members are urged to put immediately in the public
domain any genetic sequence of influenza virus they obtain.
This influenza event underlines in all countries the crucial
importance of maintaining worldwide veterinary services able to
implement in animals early detection of relevant emerging pathogens
with a potential public health impact. This capacity is fully linked
with veterinary services good governance and their compliance with
OIE international standards of quality.
--
Communicated by:
Nati Elkin
E-mail nati@poultrymed.com
[The reservations above from naming the current A (H1N1) influenza
epidemic, which started, most probably, in March 2009 in Mexico, as
"swine influenza," seem to the undersigned as fully justified.
Influenza A viruses include the avian, swine, equine, and canine
influenza viruses, as well as the human influenza A viruses. They can
cause disease in birds, swine, horses, ferrets, dogs, cats, mink,
seals, whales, and other species.
Avian influenza viruses mainly infect birds, but some strains can
also infect and/or cause disease in mammals, including humans (such
as, H5N1), without further spread among humans. Poultry can develop
serious or mild disease, depending on the subtype and strain of virus.
Equine influenza viruses mainly affect horses, donkeys, and mules;
they have also been reported in zebra. Antibodies to the equine H3N8
viruses have been reported in humans. An H3N8 equine influenza virus
appears to have jumped into dogs.
Canine influenza viruses have been seen only in dogs. To date, there
have been no infections reported in other species, including humans.
"Swine influenza" (hog flu, pig flu) in senso stricto is an animal
disease, caused by a specific porcine virus, namely swine influenza
virus (SIV). SIV's are very contagious, mainly affecting pigs, but
can sporadically cause disease in turkeys and humans. Such an
interspecies infection, when occurring, is not followed by further
spread in the affected populations ("dead end" hosts). Experimental
infections have been established in cattle, dogs, and humans.
The current A (H1N1) influenza virus spreads readily among humans
without any known involvement of, or contact with pigs; when and
where its initial reassortment took place is not (yet?) known. Such
information is, apparently, not relevant anymore to the dynamics of
the epidemic: the causative virus can persist among humans
independently of animal involvement.
As rightly remarked by my colleague, Mod.CP, in the case of the
pandemic flus, it has been the region of origin of the outbreak that
had the honour -- H1N1 in 1918 was Spanish flu, followed by Asian flu
(H2N2) in 1957, Hong Kong flu (H3N2) in 1968, and reappearance of
H1N1 (as Russian flu) in 1977. Hence, the current epidemic, even if
becoming a pandemic, deserves the name "Mexican flu" (or, as
suggested by the OIE, "North American flu"), rather than swine flu.
The designation as "swine flu" is misleading and has already led
consumers to undue concerns and several countries to impose
restrictions on the movement of animals, their products and -- at
least in one case -- other agricultural products of plant origin as
well. - Mod.AS]
[ProMED is using the term "swine flu" (in quotation marks) until a
better nomenclature is established and in order to be consistent with
common usage in the media and with CDC, other ministries of health
and WHO. We recognize that the virus has not been isolated from
swine and no evidence exists linking the current human outbreak with
exposure to swine. - Mod.LM]
[see also:
Influenza A (H1N1) "swine flu" (02): worldwide 20090427.1586
Influenza A (H1N1) "swine flu": Worldwide 20090427.1583
Influenza A (H1N1) virus, human: worldwide 20090426.1577
Influenza A (H1N1) virus, human - New Zealand, susp 20090426.1574
Influenza A (H1N1) virus, human - N America (04) 20090426.1569
Influenza A (H1N1) virus, human - N America (03) 20090426.1566
Influenza A (H1N1) virus, human - N America (02) 20090425.1557
Influenza A (H1N1) virus, human - N America 20090425.1552
Acute respiratory disease - Mexico, swine virus susp 20090424.1546
Influenza A (H1N1) virus, swine, human - USA (02): (CA, TX) 20090424.1541
Influenza A (H1N1) virus, swine, human - USA: (CA) 20090422.1516
Influenza A (H1N1) virus, swine, human - Spain 20090220.0715
2008
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Influenza A (H1N1) virus, swine, human - USA (TX) 20081125.3715
2007
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Influenza A (H2N3) virus, swine - USA 20071219.4079
2006
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Influenza, swine, human - USA (IA): November 2006 20070108.0077]
...................................arn/mj/lm
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