Bordetella pertussis. B.paratussis causes parapertussis.
5 - 21 days (average 7 days)
From catarrhal stage till 3 weeks after onset of typical paroxysm in patients not treated with antibiotics. If antibiotic therapy initiated, period of infectiousness is usually 5 days or less after onset of therapy. A highly contagious disease with an 80% attack rate in non-immune persons.
Via respiratory droplets or direct contact with nasal or throat secretions of an infected person. Adolescents and adults with unrecognized pertussis are a reservoir of infection for infants and children.
- The disease is far more severe in children and may be fatal in infants. The highest incidence continues to be in infants (<6 months) who are either unimmunised or incompletely immunised with the primary course of vaccination.
- Increasing incidence in adolescents and adults (with occasional community and school outbreaks) noted in many industrialised countries due to waning vaccine immunity. The true disease burden is however under-estimated due to low recognition, reporting and limitations in diagnostic testing.
- In Singapore, a sharp increase in the incidence of pertussis from an annual average of 4 laboratory confirmed cases to 38 cases was reported in 2007. The highest incidence rate was observed in children under 6 months of age. Among the three major ethnic groups, Malays had the highest incidence rate followed by Chinese and Indians. Only nine cases had at least one dose of DTP vaccination prior to onset of illness.