Which disease category has humans as the only known reservoir?

• A. Epidemic
• B. Pandemic
• C. Anthroponoses
• D. Zoonoses

Answer: (C)

Anthroponoses are diseases for which humans are the only known reservoir. A reservoir is the population in which a pathogen normally lives and multiplies; when only humans harbor it, the pathogen is maintained solely through human-to-human transmission, with no non-human hosts required. This makes control rely heavily on interrupting person-to-person spread, through vaccination, case finding, and isolation. Classic examples include measles, rubella, diphtheria, and poliomyelitis; smallpox is another historic case that has been eradicated. In contrast, epidemic or pandemic describes the size of an outbreak, not the reservoir. Zoonoses involve animal reservoirs, meaning non-human hosts are part of the pathogen’s life cycle.