Plan for pandemic "Swine Flu'

1.1 Influenza

Influenza virus can infect both human beings and animals notably pigs, birds, horses etc. Three types of influenza viruses are known, namely A, B and C. While humans may be affected by all the three influenza viruses, in lower animals and birds, influenza A viruses are of primary concern. Influenza A virus causes infection in humans all round the year and is responsible for most of the seasonal epidemics and pandemics. Influenza B causes sporadic and less severe outbreaks whereas the type C causes mild respiratory illness.

Influenza A viruses are divided into subtypes based on two glycoproteins (haemagglutinin and neuraminidase antigens) present on the surface of the virus. There are 16 haemagglutinin (H) antigens (1 to 16) and 9 neuraminidase (N) antigens (1 to 9). The viruses can have different combinations of H and N antigens. While all 16 haemagglutinin subtypes of influenza A viruses readily infect the birds, viruses having any of the H1, H2 or H3 haemagglutinin antigens and any of the N1 or N2 neuraminidase antigens only affect the humans usually. In fact, H1N1, H2N2, and H3N2 subtypes of influenza A virus have been associated with most of the widespread epidemics and all the pandemics of the past.

1.2 Influenza A H1N1

Influenza A H1N1 is a circulating seasonal influenza virus that caused pandemic in 1918-1919. The present pandemic is being caused by a new sub type of Influenza A H1N1 which has re-assorted with antigenic segments from American swine, Eurasian Swine, avian and human influenza virus. The majority of these cases have occurred in otherwise healthy young adults. The incubation period is from 1-7 days. The virus is spreading from human to human through droplet infection. The period of communicability is from 1 day before to 7 days after the onset of symptoms. It may be longer in children (up to 3 weeks) The virus is currently sensitive to Oseltamivir.

1.3 Global Scenario

This sub type of Influenza A [H1N1], was first reported in Mexico on 18th March, 2009 and then spread to neighbouring United States and Canada. As on 8th June, 2009, World Health Organization has reported 25,288 laboratory confirmed cases of influenza A/H1N1 infection with 139 deaths from 73 countries spread over America, Europe, Asia and Australian continent.


1.4 Situation in India

As on 29.052009 there is one imported case that came from U.S.A. There has been no secondary spread from that index case. However, with efficient human to human transmission established and more than 48 countries involved, it is a matter of time that this pandemic strain would come to India. The behavior of this mutant virus among the Asian population cannot be predicted. The virus has the potential to mutate further and become a lethal virus .

1.5 Current WHO phase of Pandemic Alert
World Health Organization has officially designated the present outbreak as public health emergency of international concern and has raised the pandemic alert phase to level -5 implying widespread human transmission. WHO has stated that containment may not be possible at this stage and is advocating mitigation measures. It has recommended against closing borders and restricting or banning air travel from affected countries.