Which of the following is a mode of transmission for Yersinia pestis?

Which of the following is a mode of transmission for Yersinia pestis?

• A. Ingestion of contaminated water
• B. Sexual transmission
• C. Flea bite
• D. Person-to-person casual contact

Answer: (C)

Yersinia pestis is transmitted to humans primarily through the bite of an infected flea that has fed on an infected rodent reservoir. The bacterium colonizes the flea’s gut and can form a blockage, causing the flea to regurgitate bacteria into the bite site during feeding, which initiates infection. The other routes listed aren’t typical means of acquiring plague—ingestion of contaminated water isn’t a characteristic transmission pathway, sexual transmission isn’t described for Y. pestis, and casual person-to-person contact isn’t the usual route (though pneumonic plague can spread by respiratory droplets between people in close contact). Thus, the flea bite is the correct mode of transmission.

Yersinia pestis is transmitted to humans primarily through the bite of an infected flea that has fed on an infected rodent reservoir. The bacterium colonizes the flea’s gut and can form a blockage, causing the flea to regurgitate bacteria into the bite site during feeding, which initiates infection. The other routes listed aren’t typical means of acquiring plague—ingestion of contaminated water isn’t a characteristic transmission pathway, sexual transmission isn’t described for Y. pestis, and casual person-to-person contact isn’t the usual route (though pneumonic plague can spread by respiratory droplets between people in close contact). Thus, the flea bite is the correct mode of transmission.