SWINE FLU - PAST AND A CONCERN FOR FUTURE

Dr. Anil M. Mane*

ABSTRACT

Influenza viruses are viruses which cause mild to severe respiratory infections. They belong to the family Orthomyxoviridae and are classified into three types, A, B, and C, based on the variation in the structure of their surface proteins. Influenza A infects many mammals and aquatic birds and is the most common and the most severe pathogen among the three types. Influenza B is almost exclusively a human pathogen, whereas Influenza C causes milder disease and is less common than the other types. Influenza A viruses are further classified into subtypes based on the surface glycoproteins hemagglutinin (1-16 subtypes of HA) and neuraminidase (1-9 subtypes of NA). At a given time, the most common subtypes circulating in' human populations are H1N1 and H3N2. The last century witnessed three Influenza pandemics - the Spanish Flu caused by H1N1 (1918-1920), the Asian Flu caused by H2N2 (1957-1958), and the Hong Kong Flu caused by H3N2 (1968-1969).

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