Oocyst of toxoplasma is found in –
**Core Concept**
Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii, a protozoan that undergoes a complex life cycle involving multiple hosts. The oocyst is a key stage in the life cycle of T. gondii, which is crucial for the transmission and survival of the parasite.
**Why the Correct Answer is Right**
The oocyst of Toxoplasma gondii is formed in the intestinal epithelial cells of cats (definitive hosts), which are the primary hosts for the parasite. The oocysts are shed in the feces of infected cats and can survive in the environment for long periods, contaminating water and food sources. When ingested by intermediate hosts (such as humans, rodents, or birds), the oocysts undergo a process called sporulation, releasing sporozoites that can infect the host's tissues.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the oocyst is not formed in the intermediate hosts, but rather in the definitive hosts (cats).
**Option B:** Incorrect because the oocyst is not found in the cyst stage, which is a different stage of the parasite's life cycle.
**Option C:** Incorrect because the oocyst is not a structure found in the parasite's tissue cysts, which are formed in the intermediate hosts.
**Clinical Pearl / High-Yield Fact**
Toxoplasmosis can be transmitted through contact with contaminated cat feces, contaminated food and water, or organ transplantation from an infected donor. Pregnant women are particularly vulnerable to toxoplasmosis, as the infection can cause congenital toxoplasmosis in the fetus.
**Correct Answer:** D.