Toxoplasma

Toxoplasma: Its Life Cycle, Symptoms, and Prevention

Life cycle

 Definitive Host: Domestic cats and other felines.

 Intermediate Hosts: Humans and other mammals.

Cycle in Cats:

1. Cats ingest cysts (e.g., from raw meat like mice).

2. Cysts release bradyzoites in the small intestine.

3. Bradyzoites infect mucosal cells and differentiate into gametocytes.

4. Gametocytes fuse to form oocysts.

5. Oocysts are excreted in cat feces.

Human Infection:

1. Ingestion of cysts via:

    Undercooked meat

    Accidental contact with cat feces

2. Cysts rupture in the small intestine, releasing forms that invade the gut wall.

3. Forms differentiate into tachyzoites (rapidly multiplying trophozoites).

4. Tachyzoites infect various tissues (e.g., brain, muscle).

5. Tachyzoites transform into bradyzoites, forming tissue cysts.

Transmission:

 Contaminated soil with cat feces ingested inadvertently.

 Consumption of undercooked meat from animals grazing in contaminated soil.

 

Laboratory Diagnosis

 Acute and Congenital Infections:

   Immunofluorescence Assays:

     Detect IgM antibodies.

   IgG Antibody Tests:

     Diagnose acute infections by observing a significant rise in antibody titer in paired sera.

 Microscopic Examination:

   Giemsa-stained preparations may reveal:

     Crescent shaped trophozoites during acute infections.

     Presence of cysts in tissues.

Treatment

 Congenital Toxoplasmosis:

   Drugs: Combination of sulfadiazine and pyrimethamine.

   Also used for disseminated disease in immunocompromised patients.

 Acute Toxoplasmosis:

   Immunocompetent Individuals:

     Typically resolves spontaneously.

   Complications (e.g., chorioretinitis):

     Requires treatment.

Prevention

 General Measures:

   Thoroughly cook meat.

   Pregnant women should:

     Avoid undercooked meat.

     Avoid contact with cat feces.

     Refrain from emptying cat litter boxes.

   Do not feed cats raw meat.