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What is Incubation period of pertussis is – and explain in detail?
Pertussis 
After an incubation period of about 1-2 weeks, the disease takes a protracted course comprising three stages, - the catarrhal, paroxysmal and Convalescent - each lasting approximately two weeks.

B. pertussis infection
              ↓
Incubation period (1-2 weeks)
             ↓
Catarrhal stage (1-2 weeks)
             ↓
Paroxysmal stage (2-4 weeks)
            ↓
Convalescent stage (1-2 weeks but may last 1 to 3 months)
Remember

Catarrhal stage is the stage of maximum infectivity.
Maximum complications occur in Paroxysmal stage.