Which disease is transmitted by fleas?

• A. Dengue fever.
• B. Plague.
• C. Leishmaniasis.
• D. Malaria.

Answer: (B)

Fleas transmit plague. The bacterium Yersinia pestis uses fleas as a vector; after feeding on an infected rodent, bacteria multiply in the flea’s gut and often cause a blockage. The blocked flea bites more aggressively and can regurgitate infected material into the next host, spreading plague to humans. The other diseases are carried by different insects: dengue fever and malaria are spread by mosquitoes (Aedes for dengue, Anopheles for malaria), and leishmaniasis by sandflies. Plague can present as bubonic, septicemic, or pneumonic forms, and public health measures focus on reducing rodent and flea exposure and ensuring rapid antibiotic treatment when needed.