Borrelia recurrentis is transmitted by –
**Question:** Borrelia recurrentis is transmitted by -
A. Ticks
B. Mosquitoes
C. Fleas
D. Fleas and ticks
**Correct Answer:** C. Fleas and ticks
**Core Concept:** Borrelia recurrentis is a bacterium that causes relapsing fever, a group of related infections caused by spirochetes. These spirochetes are transmitted by arthropod vectors, which are small, two-legged invertebrates that feed on blood. Two primary vectors for Borrelia recurrentis are fleas and ticks.
**Why the Correct Answer is Right:** Borrelia recurrentis is transmitted by fleas and ticks because:
1. Fleas: Fleas (Ceratophyllus fasciolaris) are small, blood-sucking insects that typically feed on rodents, rabbits, and other mammals. Fleas are known vectors for several pathogens, including Borrelia recurrentis. When an infected flea bites a human, the bacteria can enter the bloodstream and cause relapsing fever.
2. Ticks: Ticks are another group of blood-sucking arthropods that attach to humans and other animals to feed on their blood. Some species of ticks can transmit Borrelia recurrentis to humans, particularly those that feed on rodents, which are reservoirs for the bacterium.
**Why Each Wrong Option is Incorrect:**
A. Mosquitoes (Option B) are responsible for transmitting arboviral diseases like dengue, malaria, and Zika virus. They do not transmit Borrelia recurrentis or any spirochete-related diseases.
B. Fleas (Option A) are vectors for Borrelia recurrentis, as explained above.
C. Fleas and ticks (Option C) are the primary vectors for Borrelia recurrentis, as explained.
D. Fleas and mosquitoes (Option D) are transmitted by different vectors, as explained above. Mosquitoes transmit arboviral diseases, not spirochete-related illnesses.
**Clinical Pearl:** Relapsing fever caused by Borrelia recurrentis is an important differential diagnosis in patients presenting with fever, headache, and joint pain, especially in areas endemic for fleas and ticks. Rapid diagnosis and treatment are crucial to prevent severe complications and ensure patient recovery.