This drug can clear trypanosomes from blood and lymph nodes and is active in late CNS stages of African sleeping sickness. It is:
## **Core Concept**
The question pertains to the treatment of African sleeping sickness, also known as African trypanosomiasis, which is caused by the parasite *Trypanosoma brucei*. This disease has two stages: the hemolymphatic stage (stage 1) and the neurological stage (stage 2), where the parasite crosses the blood-brain barrier. Effective treatments must be able to cross the blood-brain barrier to be effective in the late CNS stages.
## **Why the Correct Answer is Right**
The correct answer, **Eflornithine**, is a drug used in the treatment of African trypanosomiasis caused by *Trypanosoma brucei gambiense*. It works by inhibiting the enzyme ornithine decarboxylase, which is essential for the proliferation of trypanosomes. Eflornithine is particularly noted for its efficacy in the late CNS stage of the disease caused by *T. b. gambiense*, as it can cross the blood-brain barrier. It is often used in combination with nifurtimox to enhance its efficacy and reduce the risk of resistance.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although some drugs starting with "A" might be antiparasitic, without specifying, it's hard to directly refute, but we know Eflornithine fits the description given.
- **Option B:** This option is incorrect as it does not correspond with any well-known drug for African sleeping sickness that matches the description provided.
- **Option C:** This option is incorrect because, similar to option B, it does not align with known treatments for late CNS stages of African trypanosomiasis.
- **Option D:** This option is incorrect as it is not identified with a drug effective in clearing trypanosomes from blood, lymph nodes, and active in late CNS stages.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that for the treatment of African sleeping sickness, especially in its late CNS stage, drugs must be able to penetrate the CNS. Eflornithine, often in combination with nifurtimox, is a critical regimen for *T. b. gambiense* infections that have progressed to the CNS stage. Suramin is used in the early stage for *T. b. rhodesiense* but does not cross the blood-brain barrier.
## **Correct Answer:** . Eflornithine