toxoplasma

Toxoplasma gondii(toxoplasmosis)

Introduction

Morphology

A zoitocyst of Toxoplasma gondii filled with bradyzoites; this zoitocyst is in cardiac muscle(acute stage).

A zoitocyst of Toxoplasma gondii filled with bradyzoites; this zoitocyst is in brain(chronic stage)

Toxoplasmosis oocyst
Tachyzoite stage

Symptoms

Although Toxoplasma infection is common, it rarely produces symptoms in normal individuals. Its serious consequences are limited to pregnant women and immunodeficient hosts. Congenital infections occur in about 1-5 per 1000 pregnancies of which 5-10% result in miscarriage, 8-10% result in serious brain and eye damage to the fetus, 10-13% of the babies will have visual handicaps. Although 58-70% of infected women will give a normal birth, a small proportion of babies will develop active retino-chorditis or mental retardation in childhood or young adulthood.

In immunocompetent adults, toxoplasmosis, may produce flu-like symptoms, sometimes associated with lymphadenopathy. In immunocompromised individuals, infection results in generalized parasitemia involvement of brain, liver lung and other organs, and often death.

Immunology

Both humoral and cell mediated immune responses are stimulated in normal individuals. CMI is protective and humoral response is of diagnostic value.

Diagnosis

Suspected toxoplasmosis can be confirmed by isolation of organism from tonsil or lymph gland biopsy.

Treatment

Acute infections benefit from pyrimethamine or sulphadiazine. Spiramycin is a successful alternative. Pregnant women are advised to avoid cat litter, handle uncooked meat carefully and undercooked meat.