Patient was given chloroquine and doxycycline for 7 days. Patients fever decreases in 4 days, but, peripheral smear showed occasional gametocytes of plasmodium falciparum. This type of drug resistance is –
**Core Concept**
Chloroquine and doxycycline are antimalarial drugs used to treat Plasmodium falciparum infections. However, resistance to these drugs can develop, leading to treatment failure and the persistence of gametocytes, which are the transmissible forms of the parasite.
**Why the Correct Answer is Right**
The persistence of gametocytes despite treatment with chloroquine and doxycycline suggests that the parasite has developed resistance to these drugs. This type of resistance is known as gametocytocidal resistance, where the parasite is resistant to the drugs' ability to kill the gametocytes. Chloroquine is a blood schizonticide, which means it primarily targets the asexual stages of the parasite, but it is less effective against gametocytes. Doxycycline also has some activity against gametocytes, but its effectiveness is limited in this context.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the scenario described, as it does not address the specific issue of gametocyte persistence.
* **Option B:** This option is incorrect because it does not accurately describe the type of resistance that occurs when gametocytes persist despite treatment with chloroquine and doxycycline.
* **Option C:** This option is incorrect because it refers to a different type of resistance, which is not relevant to the scenario described.
**Clinical Pearl / High-Yield Fact**
It's essential to recognize that chloroquine resistance can manifest as gametocytocidal resistance, which can lead to the persistence of transmissible gametocytes. This highlights the importance of using combination therapy and monitoring for treatment failure.
**Correct Answer: C. Chloroquine resistance.**