Main period of communicability of whooping cough?
Incubation period
Paroxysmal stage
Catarrhal stage
Convalescent stage
Ans. is 'c' i.e.,Catarrhal stage Peussis, also called '100 day cough', is caused by Bordetella peussis (only 5% cases are caused by B. parapeussis).there is no cross immunity between B. peussis and B. parapeussis.Period of infectivity (communicability) extends from a week after exposuse to about 3 weeks after the onset of paroxysmal stage. Catarrhal stage is most infective. Secondary attack rate is high, i.e. 90%.