Other Important Facts on Whooping Cough
During 2001-2003, the highest average annual whooping cough incidence was among infants younger than 1 year of age (55.2 cases per 100,000 population), and particularly among children younger than 6 months of age (98.2 per 100,000 population). In 2002, 24 percent of all reported cases were in this age group.
However, in recent years, adolescents (11-18 years of age) and adults (20 years and older) have accounted for an increasing proportion of cases. During 2001-2003, the annual incidence of whooping cough among people aged 10-19 years increased from 5.5 per 100,000 in 2001, to 6.7 in 2002, and 10.9 in 2003. In 2004, approximately 60 percent of cases were among people 11 years of age and older.
Increased recognition and diagnosis of whooping cough in older age groups probably contributed to this increase of reported cases among adolescents and adults.