Which disease is among the most serious fleas may carry?

• A. Bubonic plague
• B. Typhus
• C. Encephalitis
• D. All of the above

Answer: (A)

Fleas act as disease vectors, transferring infections from infected rodents to people when they bite. Among the diseases listed, bubonic plague is the most serious flea-borne illness. It is caused by Yersinia pestis and can progress to septicemic or pneumonic plague, making it a major concern in pest control and public health. Typhus is commonly spread by lice, with fleas able to carry related organisms only in some cases, and it is generally less severe than plague. Encephalitis is typically transmitted by mosquitoes or ticks, not fleas. So bubonic plague is the best answer because fleas are classically linked to transmitting this highly serious disease.