The etiological agent causing endemic typhus is

The etiological agent causing endemic typhus is

• A. Rickettsia prowazekii
• B. Rickettsia rickettsii
• C. Yersinia pestis
• D. Vibrio cholerae

Answer: (A)

Endemic typhus is caused by a Rickettsia species transmitted to humans by fleas that feed on rodents. The specific agent is Rickettsia typhi, which cycles between rats and rat fleas and can infect people. This is different from epidemic typhus, which is caused by Rickettsia prowazekii and spread by body lice. Among the listed organisms, the one associated with typhus in general is a Rickettsia, but the exact agent for endemic typhus is typhi, not prowazekii. The other organisms correspond to entirely different diseases: Rickettsia rickettsii causes Rocky Mountain spotted fever; Yersinia pestis causes plague; Vibrio cholerae causes cholera. The key point is distinguishing the two typhus forms by their vector and their specific Rickettsia species.

Endemic typhus is caused by a Rickettsia species transmitted to humans by fleas that feed on rodents. The specific agent is Rickettsia typhi, which cycles between rats and rat fleas and can infect people. This is different from epidemic typhus, which is caused by Rickettsia prowazekii and spread by body lice. Among the listed organisms, the one associated with typhus in general is a Rickettsia, but the exact agent for endemic typhus is typhi, not prowazekii. The other organisms correspond to entirely different diseases: Rickettsia rickettsii causes Rocky Mountain spotted fever; Yersinia pestis causes plague; Vibrio cholerae causes cholera. The key point is distinguishing the two typhus forms by their vector and their specific Rickettsia species.