Pertussis is an acute infectious disease of young children, caused by B. pertussis. It is characterized by mild fever and an irritating cough with a characteristic ‘whoop’. Chinese call it a ‘Hundred Day Cough’.
Agent: Causative agent is a bacteria named Bacillus pertussis. The bacteria elaborates an exotoxin and endotoxin.
Source of Infection: B pertussis infects only man. Source of infection is a case of pertussis. Chronic carrier state does not exist.
Infective Material: the bacteria occurs in nasopharyngeal and bronchial secretions and freshly contaminated objects are also infective.
Period of Infectivity: one week after exposure to about three weeks.
Age and Sex: it is a disease of infants and preschoolers. Highest incidence is found in children below 5 years of age. Infants below 6 months are at risk of mortality. The disease is known affect females more than males.
Immunity: recovery from infection and immunization provides adequate immunity. Infants are susceptible to infection right from birth as maternal antibody does not provide protection.
Pertussis occurs throughout the year, but seasonal variations are seen with higher incidence in winter and spring months due to overcrowing. Socio-economic conditions and way of life also play a role in the occurrence of pertussis.
The disease is spread mainly by droplet infection and direct contact. The bacilli are sprayed in air when the infected person coughs, sneezes, or talks. The role of fomites is very small unless freshly contaminated.
Incumbation Period: 7 to 14 days, but not more than 3 weeks
Cases and Carriers: early detection, isolation, treatment of the cases and disinfection of discharges from nose and throat help in control. Infants and young children should be kept away from infected person.
Active Immunization: Immunization against pertussis with DPT is an effective means of control and prevention of the disease.