Etiologic Agent Bordetella pertussis , a gram-negative coccobacillus. This disease results in high morbidity and mortality in many countries every year. In the United States, 5000-7000 cases are reported each year. Incidence of pertussis has increased steadily since the 1980s. Complications Major complications are most common among infants and young children and include hypoxia, apnea, pneumonia, seizures, encephalopathy, and malnutrition.
Most deaths occur among unvaccinated children or children too young to be vaccinated.
Transmission Occurs through direct contact with discharges from respiratory mucous membranes of infected persons. Risk Groups Children who are too young to be fully vaccinated and those who have not completed the primary vaccination series are at highest risk for severe illness. Adolescents and adults become susceptible when immunity wanes. Trends Pertussis is an endemic illness. In the United States epidemics occur every 3-5 years.