“Endemic” typhus is transmitted by:
**Core Concept**
Endemic typhus, also known as murine typhus, is a zoonotic disease caused by the bacterium *Rickettsia typhi*. It is transmitted through the bites of infected fleas, typically those found on rodents and other small mammals.
**Why the Correct Answer is Right**
The correct answer is related to the primary vector responsible for transmitting endemic typhus. The bacterium *Rickettsia typhi* is ingested by the flea while feeding on an infected host, and then the bacteria multiply within the flea's midgut. When the infected flea defecates on a new host, the bacteria are regurgitated and enter the host through a bite wound, causing infection. This mechanism highlights the importance of fleas as vectors in the transmission of endemic typhus.
**Why Each Wrong Option is Incorrect**
**Option A:** Ticks are vectors for other tick-borne diseases such as Lyme disease and Rocky Mountain spotted fever, but they are not primarily associated with endemic typhus.
**Option B:** Mosquitoes are vectors for various diseases like malaria and dengue fever, but they are not involved in the transmission of endemic typhus.
**Option C:** Mites can transmit diseases like scrub typhus, but they are not the primary vectors for endemic typhus.
**Clinical Pearl / High-Yield Fact**
Endemic typhus is often confused with other rickettsial diseases, but it is typically characterized by a more gradual onset of symptoms and a higher incidence in the summer months. The disease is also known as murine typhus due to its association with rodents.
**Correct Answer: C. Lice.**