ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Fri 26 Jun 2009
Source: DEFRA, Global Animal Health - International Disease Monitoring.
Preliminary Outbreak Assessment.Reference: VITT 1200 / H1N1 Influenza A in
Argentina pigs [edited]
A novel influenza A/H1N1 in pigs in Argentina
--------------------------------------------
1. Introduction
---------------
Argentina has reported an outbreak of influenza A/H1N1 in a commercial pig
farm in the Buenos Aires region [a map is included at the above URL]. The
authorities have qualified this outbreak as "a new emerging disease" in the
report. Introduction of the infection was attributed to human to animal
transmission from workers at the farm who showed flu signs between 7 and 9
Jun 2009. According to the report, the farm was restocked from their own
restocking system in July 2008. The infected pigs showed clinical signs up
to 24 Jun 2009 and have now recovered. The report states that in a total
population of over 5500 pigs (mixed ages) there was 30 percent morbidity
but no mortality (OIE, 2009).
2. Situation assessment
-----------------------
This is only the 2nd time that a report to OIE qualified findings of
influenza A/H1N1 in domestic pigs as "a new emerging disease". The 1st
report related to a pig population in Canada in April 2009. Influenza A in
pigs usually has a relatively short period of incubation (most often days,
rather than weeks). Given the company restocking system and that restocking
took place in mid-2008, it would be highly unlikely that this virus was
present in this pig population before and remained undetected. The World
Health Organisation (WHO) declared recently that novel influenza A/H1N1 has
reached phase 6 of global pandemic status. To date, there have been nearly
60 000 laboratory confirmed human cases and 263 deaths reported.
Confirmation of the virus in a relatively limited number of humans was
reported from 105 countries. A limited number of these countries have
reported deaths in humans, mainly in people with underlying health
conditions (WHO, 2009).
The World Organisation for Animal Health (OIE) maintains that previous
recommendations for OIE member countries remain valid. Namely, to monitor
animal populations for signs of clinical diseases in animals; that pork and
pork products handled hygienically are not a source of infection; that
there is no justification for any ban on pigs and pig products; culling
pigs is not recommended for animal health reasons and, if so, that any
culling should be carried out according to international animal welfare
standards (OIE, 2009a).
An EU study group coordinated by the Veterinary Laboratories Agency,
Weybridge, UK, (VLA) has completed preliminary tests on the infection of
pigs with a human-derived strain of the new variant H1N1 influenza virus.
Briefly, naive pigs, inoculated intranasally, shed virus (orally and
ocular) for between 1 and 10 days post-infection (dpi) with a peak at 3-5
dpi. No rectal shedding or viraemia was detected. Uninfected pigs
introduced to these infected animals also became infected after contact.
All infected pigs developed mild to moderate clinical and pathological
signs only. (EU Study, 2009).
Accumulated evidence so far suggest that the new variant Influenza A/H1N1
continues to be primarily a human-to-human transmissible infection which
generally causes mild disease in infected people. Experimental data on pig
infections with this strain indicate that infection is localised to
respiratory tract and that viraemia is highly unlikely to be of any
significance as one of the feature of the disease. Infection also causes a
relatively mild disease in pigs. In a separate study turkeys directly
challenged with the virus did not apparently become infected. Argentina is
not an approved country for export of pigs or pig products to the EU.
The Pig Veterinary Society has published advice to pig keepers on
protecting their herds from the risk of introducing new variant Influenza
A/H1N1 (Pig Veterinary Society, 2009).
3. Conclusions
--------------
On the basis of available information, we currently consider that there
would be a negligible risk of introducing this Influenza A/H1N1 from
Argentina to the UK by the legal import of pigs or pig products because
such imports are not allowed. As this latest report may indicate, another
possible route for disease introduction into pig herds in the UK would be
people that may be infected and have direct or indirect contact with a pig
farm. Therefore, it is important to continue to monitor for, and report and
submit samples from suspected influenza signs in pigs (according to
appropriate case algorithms) to relevant authorities, and maintain
appropriate biosecurity measures at pig farms at all times. We will
continue to review the situation.
4. Authors
----------
Dr Mirzet Sabirovic
Dr Helen Roberts
5. References
-------------
- EU Study (2009)
Accessed 26 Jun 2009.
- OIE (2009) Immediate Notification report Reference ARG-26-06-09.
Accessed 26 Jun 2009.
- OIE (2009a) Novel influenza A/H1N1 pandemic: the OIE maintains its
recommendations to animal health authorities worldwide.
- Pig Veterinary Society (2009) Novel Influenza A H1N1 Virus protecting
pigs, protecting people.
- WHO (2009) Laboratory-confirmed cases of new influenza A(H1N1) as
officially reported to WHO by States Parties to the International Health
Regulations (2005)
--
communicated by:
Myrtle O'Keefe (FFG)
myrtle.o'keefe@defra.gsi.gov.uk
[As this is the first recorded transmission of the 2009 (swine origin) A
(H1N1) influenza virus from humans to pigs, these observations need to be
substantiated by a molecular comparison of viruses recovered from the two
hosts. As recorded in the ProMED-mail references listed below the origin of
the A (H1N1)virus infecting pigs in a Canadian farm is unknown. Initially
it was infered that the virus had been transmitted via a farm worker
recently returned from Mexico. Subsequently it was established that the
farm worker was not infected and the origin of the Canadian outbreak
remains unresolved. - Mod.CP
Though the facts in the above analysis by DEFRA's GAH experts have already
been available to ProMED-mail's subscribers, it seemed to us worthwhile
posting the review as an all-round, documented update. - Mod.AS]
[see also:
Influenza A (H1N1) - worldwide (78): Tamiflu resistance, DK 20090630.2359
Influenza A (H1N1): animal health (16), Argentina, swine, OIE 20090626.2322
Influenza A (H1N1): animal health (15), Egypt, pig cull 20090617.2241
Influenza A (H1N1): animal health (14), EU preparedness, Egypt 20090615.2220
Influenza A (H1N1): animal health (13) swine, Canada, origin, RFI
20090615.2215
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 (08), food safety, FAO/OIE/WHO 20090507.1710
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
Influenza A (H1N1): animal health (03), Egypt, pig cull 20090502.1649
Influenza A (H1N1): animal health 20090430.1637
Influenza A (H1N1), "swine flu": animal health (02), Egypt, prevention
20090429.1623
Influenza A (H1N1), "swine flu": animal health 20090428.1604]
.................cp/arn/ejp/sh
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