A man present with fever, chills 2 weeks after a louse bite. There was maculopapular rash on the trunk which spread peripherally. The cause of this infection can be –
**Core Concept**
The patient's symptoms, including fever, chills, and a maculopapular rash spreading peripherally, are characteristic of a tick-borne or vector-borne infection. In this case, the louse bite suggests a zoonotic disease transmitted by an ectoparasite.
**Why the Correct Answer is Right**
The patient's symptoms are likely due to **Borrelia recurrentis**, the causative agent of Louse-borne Relapsing Fever (LBRF). This spirochetal infection is transmitted through the bite of an infected human body louse (Pediculus humanus corporis). The bacteria multiply in the louse's gut and are then regurgitated into the human host's bloodstream, causing fever, chills, and a maculopapular rash that spreads peripherally.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because **Borrelia burgdorferi** is the causative agent of Lyme disease, which presents with a different set of symptoms, including a characteristic "bull's-eye" rash.
* **Option B:** This option is not only incorrect but also irrelevant, as it mentions **Leptospira**, the causative agent of Leptospirosis, which is a water-borne disease.
* **Option C:** This option is incorrect because **Rickettsia rickettsii** is the causative agent of Rocky Mountain Spotted Fever (RMSF), which presents with a different set of symptoms, including a characteristic rash and fever.
**Clinical Pearl / High-Yield Fact**
In cases of suspected vector-borne disease, it's essential to consider the patient's travel history, exposure to ticks or lice, and the time of year when the infection is most common. Additionally, a thorough physical examination, including a search for ticks or lice, can help guide diagnosis.
**Correct Answer: B. Borrelia recurrentis**