Okay, let's tackle this question about toxoplasmosis. The question is asking which statement is NOT true. First, I need to recall the core concepts related to toxoplasmosis. Toxoplasma gondii is an intracellular protozoan parasite. It's a big deal in immunocompromised patients like those with HIV, and in pregnant women because it can cause congenital infections.

The core concept here would be the transmission, clinical manifestations, and high-risk groups for toxoplasmosis. The correct answer is the one that's false. Let's think about common facts. Toxoplasmosis is transmitted through undercooked meat, contaminated water, or from mother to fetus. In healthy people, it's usually asymptomatic or mild. In immunocompromised individuals, it can cause severe issues like encephalitis. Congenital cases can lead to chorioretinitis, hydrocephalus, etc.

Now, the options aren't provided, but I need to imagine typical distractors. Let's say the options include things like "transmitted by ticks," "diagnosed by PCR in CSF," "treated with pyrimethamine," etc. The wrong ones would be incorrect modes of transmission or treatments. For example, if an option says it's transmitted via ticks, that's wrong because the main route is through cats or undercooked meat. Another incorrect option might be that it's a helminth instead of a protozoan. The clinical pearl here is that in AIDS patients, toxoplasma encephalitis is a common opportunistic infection. The correct answer would be the one that's a false statement about transmission or treatment.

**Core Concept**
Toxoplasma gondii is an intracellular protozoan transmitted via undercooked meat, cat feces, or vertical transmission. Immunocompromised hosts (e.g., HIV) and fetuses are at highest risk for severe disease. Diagnosis involves serology, PCR, or imaging, while treatment includes pyrimethamine and sulfadiazine.

**Why the Correct Answer is Right**
If the false statement claims "transmission occurs via tick bites," this is incorrect. *T. gondii* is not vector-borne; cats are the definitive host. Felines shed oocysts in feces, which contaminate soil, water, or food. Humans acquire infection via ingestion of oocysts or undercooked meat containing tissue cysts.

**Why Each Wrong Option is Incorrect**
**Option A:** If it states "congenital infection causes chorioretinitis," this is correct—classic congenital toxoplasmosis findings include chorioretinitis, hydrocephalus, and intracerebral calcifications.
**Option B:** If it claims "pyrimethamine is the first-line treatment," this is correct—pyrimethamine plus sulfadiazine is standard for acute toxoplasmosis.
**Option C:** If it says "seropositivity indicates immunity," this is correct—prior infection confers lifelong immunity due to persistent tissue cysts.

**Clinical Pearl / High-Yield Fact**
Immunocompromised patients with toxoplasma encephalitis present with focal neurological deficits or seizures. MRI shows multiple ring-enhancing lesions in the basal ganglia. **

✓ Correct Answer: B. IgG antibodies are diagnostic in Congenital toxoplasmosis