**Question:** Ovoviviparous parasite which is associated with autoinfection -

A. Schistosoma
B. Plasmodium
C. Trypanosoma
D. Leishmania

**Correct Answer:** B. Plasmodium

**Core Concept:**
Autoinfection in parasites refers to the process where the parasite infects a new host from within the original host. In the context of the question, we are discussing a parasite that exhibits autoinfection during its life cycle. Ovoviviparous reproduction is a reproductive strategy where the female parasite develops its offspring within its body, while the male parasite remains external.

**Why the Correct Answer is Right:**
Plasmodium is a genus of protozoan parasites that are responsible for causing malaria in humans. The life cycle of Plasmodium involves the transmission from an infected mosquito to the human host, followed by sexual reproduction (ovoviviparous) within the human liver and red blood cells. Autoinfection occurs when the parasite releases sporozoites into the bloodstream, which then invade the liver and multiply, eventually forming merozoites. These merozoites invade red blood cells, where they multiply and cause symptoms of malaria.

**Why Each Wrong Option is Incorrect:**

A. Schistosoma: This refers to a group of parasitic flatworms causing schistosomiasis, which is a distinct disease caused by a different type of parasite. Schistosoma does not exhibit ovoviviparous reproduction nor is it associated with autoinfection.

C. Trypanosoma: Trypanosoma is a group of protozoan parasites causing diseases like African sleeping sickness and Chagas disease. Trypanosoma does not involve ovoviviparous reproduction or autoinfection.

D. Leishmania: Leishmaniasis is caused by Leishmania parasites. Leishmania undergoes amitosis (a form of asexual reproduction) and does not exhibit ovoviviparous reproduction or autoinfection.

**Clinical Pearl:**
Understanding the reproductive strategies and life cycles of parasites is crucial for diagnosing and treating infections. Malaria is a notorious example of a parasitic disease caused by Plasmodium species, which exhibits ovoviviparous reproduction and autoinfection, making Plasmodium the correct answer.