Chronic carriers are typically associated with dissemination of which organism?

• A. Bordetella pertussis
• B. Campylobacter jejuni
• C. Salmonella Typhi
• D. Yersinia pestis

Answer: (C)

Chronic carriers are people who continue to harbor and shed the organism after apparent recovery, allowing ongoing spread to others. Salmonella Typhi is the classic example because many individuals who recover from typhoid fever can persist in the gallbladder and biliary system for years, shedding bacteria in bile and stool. This enables person-to-person transmission through contaminated food or water, driving sustained outbreaks even when active illness isn't evident in those who ingest the bacteria.

Bordetella pertussis causes whooping cough and is mainly spread during the acute illness, not from long-term asymptomatic carriage. Campylobacter jejuni typically causes short, self-limited illness with limited long-term carriage contributing to widespread dissemination. Yersinia pestis relies on flea vectors and environmental reservoirs for transmission, not chronic human carriers disseminating the organism.