Human Swine Flu

An influenza (flu) pandemic is a flu outbreak that occurs worldwide when:

  • A new strain of flu virus emerges, to which no-one is immune
  • The virus causes disease in humans
  • The virus is easily spread between humans

A new influenza strain can spread rapidly across the globe with high numbers of cases and deaths.

New influenza viruses may originate from influenza viruses that cause illness in pigs or birds.

H1N1 Influenza 09 (Human Swine Flu)

In 2009 the World Health Organisation (WHO) declared the first global influenza pandemic in 41 years and raised the alert level to Phase 6. This phase is characterised by community level outbreaks in at least one other country, in a different region from the source country.

  • Swine influenza, or "swine flu", is a highly contagious acute respiratory disease of pigs, caused by one of several swine influenza A viruses
  • Outbreaks in pigs occur year round with increased incidence in autumn and winter in temperate zones
  • Morbidity tends to be high and mortality low (1-4%). Many countries routinely vaccinate swine populations against swine influenza
  • The virus is spread among pigs by aerosols, direct and indirect contact, and asymptomatic carrier pigs