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Key Facts on the Outbreaks of Pandemic Influenza A/H1N1 2009 (29 September 2009)

Human cases of pandemic influenza A/H1N1 virus were identified in North America in April, and have now been detected worldwide.

This is a human health matter. The Department of Health & Children (and its agencies) is the lead Department.  For updates on the situation and human health advice you are directed to the following websites:

Department of Health and Children

Health Protection and Surveillance Centre

Health Services Executive

World Health Organisation

European Centre for Disease Control

DG SANCO Public Health

Key facts about the disease:

  1. This strain of influenza A/H1N1 virus had not been detected in pigs or in humans before 14 April 2009.
  2. The virus contains genes from pigs, birds and humans.
  3. The virus is mainly transmitted human-to-human, but some human-to-pig transmission has occurred.
  4. The virus was confirmed in Northern Ireland for the first time on 16 September and in Ireland on 29 September 2009.
  5. The virus causes mild clinical disease in the pigs.
  6. The FAO, WHO and OIE issued a joint statement on 7 May 2009: "In the ongoing spread of influenza A (H1N1), concerns about the possibility of this virus being found in pigs and the safety of pork and pork products have been raised. Influenza viruses are not known to be transmissible to people through eating processed pork or other food products derived from pigs."
  7. A Code of Practice has been produced by the Department of Agriculture in conjunction with the pig industry, to assist herd owners in managing the disease when pigs are suspected or confirmed to be infected with the pandemic strain of influenza A/H1N1 (see below).

Swine influenza in pigs:

Swine influenza is a disease of pigs caused by a virus (influenza virus). Influenza viruses exist as various types and the most common type found in pigs is Type A. The virus is present in all pig producing countries, including Ireland. Type A strains can also infect other species, including people, although the strains of virus involved are usually different. However pigs have been described as 'mixing vessels' for the various influenza virus strains (including the strains causing avian influenza). This means that they may have a role in the spread of influenza viruses between species or in the development of new strains of virus.

Swine influenza in Ireland:

This disease is a scheduled and notifiable disease in Ireland.  Two types of virus have been isolated in Ireland - a H1N1 was isolated for the first time in November 1991, and H3N2 was isolated for the first time in June 1993. The H1N1 that has circulated in Ireland since 1991 is different from the strains circulating in Europe and elsewhere, and probably represents a separate introduction of an avian strain into Irish pigs. The pandemic strain of H1N1 2009 was detected for the first time on 29 September 2009.

Although some swine influenza vaccines are available, these are not normally used in Ireland, and current vaccine strains will not protect pigs against the pandemic strain of H1N1.

Code of Practice for pandemic influenza A/H1N1 in pigs:

The most likely way that this new strain of influenza A/H1N1 could be introduced into pigs is via an infected person or by the movement of pigs from an infected herd. In order to reduce this possibility, reinforcement of the following normal biosecurity measures on pig farms should be employed. A Code of Practice for Pandemic Influenza A/H1N1 in Pigs has been drawn up. This contains details of how to prevent the introduction of the virus and how to manage the disease if it is confirmed in a herd.

Clinical signs of influenza in pigs:

Sudden onset of fever, depression, coughing, ocular and/or nasal discharge, sneezing, difficulty breathing, conjunctivitis, reduced feed consumption and abortion.

Clinical signs of influenza in humans:

Fever, cough or runny nose, sore throat and sometimes body aches, headache, chills, fatigue, vomiting and diarrhoea.