**Core Concept**
Tick-borne relapsing fever (TBRF) is a vector-borne infectious disease caused by various species of Borrelia bacteria, transmitted to humans through the bites of infected soft ticks (genus Ornithodoros). The disease is characterized by recurring episodes of fever, headache, and muscle pain.

**Why the Correct Answer is Right**
Borrelia duttonii is one of the primary causative agents of TBRF in Africa and Asia. The bacteria are transmitted to humans through the bites of infected soft ticks, which feed on the blood of small mammals and humans. The spirochetes multiply in the tick's midgut and are then transmitted to the host through the tick's saliva during feeding. The infection causes a relapsing fever, with recurring episodes of fever and other symptoms, due to the periodic release of spirochetes from the host's tissues.

**Why Each Wrong Option is Incorrect**
**Option A:** Borrelia recurrentis is the causative agent of louse-borne relapsing fever (LBRF), not tick-borne relapsing fever. LBRF is transmitted through the bites of infected human body lice (Pediculus humanus).
**Option C:** Borrelia burgdorferi is the causative agent of Lyme disease, a different tick-borne illness, not relapsing fever.
**Option D:** While multiple Borrelia species can cause TBRF, the question specifically asks for the correct answer, which is Borrelia duttonii.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that TBRF is a zoonotic disease, meaning it can be transmitted from animals to humans, and that the soft ticks that transmit the disease are typically found in areas with high rodent activity.

**✓ Correct Answer: B. Borrelia duttonii**