The bacterium Bordetella pertussis.
Pertussis (whooping cough) is a highly contagious acute bacterial disease involving the respiratory tract. It is transmitted by direct contact with airborne discharges from the respiratory mucous membranes of infected individuals.
Nature of the disease
Typical manifestations include severe cough of several weeks’ duration with a characteristic whoop, often with cyanosis and vomiting. In young infants, the cough may be absent and disease may manifest with spells of apnoea. Although pertussis can occur at any age, most serious cases and fatalities are observed in early infancy and mainly in developing countries. Major complications include pneumonia, encephalitis and malnutrition (due to repeated vomiting). Vaccination is the most rational approach to pertussis control.
WHO estimated that about 16 million cases of pertussis occurred worldwide in 2008, 95% of which were in developing countries, and that some 195 000 patients died from this disease.
Risk for travellers
Unprotected young infants are at highest risk of severe pertussis, but older children, adolescents and adults may also contract the disease (often in mild and atypical form) if they are not fully immunized. Exposure to pertussis is more frequent in developing countries.