Epidemiology
Diphtheria Epidemiology
Reservoir
human carriers
usually asymptomatic
Transmission
respiratory
skin and fomites rarely
Temporal pattern
winter and spring
Communicability
without antibiotics, seldom more than 4 weeks
Occurrence
Diphtheria occurs worldwide, particularly in tropical countries. Diphtheria is a rare disease in industrialized countries including the United States. In the United States during the pre-vaccine era, the highest incidence was in the Southeast during the winter.
Reservoir
Human carriers are the reservoir for C. diphtheriae and are usually asymptomatic. In outbreaks, high percentages of children are found to be transient carriers.
Transmission
Transmission is most often person-to-person spread from the respiratory tract. Rarely, transmission may occur from skin lesions or articles soiled with discharges from lesions of infected persons (fomites).
Temporal Pattern
In temperate areas, diphtheria most frequently occurs during winter and spring.
Communicability
Transmission may occur as long as virulent bacilli are present in discharges and lesions. The time is variable, but without antibiotics, organisms usually persist 2 weeks or less and seldom more than 4 weeks. Chronic carriers may shed organisms for 6 months or more. Effective antibiotic therapy promptly terminates shedding.