a) Age : In India, polio is essentially a disease of infancy and
childhood. About 50 per cent of cases are reported in infancy.
The most vulnerable age is between 6 months and 3 years.
b) Sex : Sex differences have been noted in the ratio of 3 males to one female.
c) Risk factors : Several provocative or risk factors have been found to
precipitate an attack of paralytic polio in individuals already infected with
polio viruses. The include fatigue, trauma, intramuscular injections, operative
procedures such as tonsillectomy under taken especially during epidemics of
polio and administration of immunizing agents particularly alum containing
DPT.
Environmental factors
Polio is more likely to occur during the rainy season. Approximately
60- per cent of cases recorded in India were during June to September.
