Trench fever is caused by: September 2004
**Core Concept**
Trench fever, also known as five-day fever, is a disease caused by a specific bacterium. The underlying principle being tested here involves the identification of the causative agent of this condition, which is transmitted by the **body louse**. This disease is characterized by recurring episodes of fever.
**Why the Correct Answer is Right**
Although the exact answer choice is not provided, the correct answer is **Bartonella quintana**. This bacterium is the causative agent of trench fever, and its transmission is facilitated by the **body louse** (Pediculus humanus), which acts as a vector. The disease manifests with symptoms such as fever, headache, and pain in the legs.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not the causative agent of trench fever.
**Option C:** Incorrect as it does not correlate with the transmission or causation of trench fever.
**Option D:** Incorrect because it is unrelated to the disease in question.
**Clinical Pearl / High-Yield Fact**
Trench fever is a classic example of a vector-borne disease, where the **body louse** plays a crucial role in transmission. Remembering the association between **Bartonella quintana** and the **body louse** is key to diagnosing and understanding the epidemiology of this condition.
**Correct Answer:** **B. Bartonella quintana**