Toxoplasma gondii

MORPHOLOGY
Pseudocytes: intercellular collection of trophozites in macrophages and reticuloendothelial cells in the acute stage of infection.
Trophozites:obligate intracellular parasites,about 6x2mm, crescent shaped with central nucleus and multiply by binary fission formind pseudocytes.

Cysts: collection of trophozites (cystozoites-bradyzoites) enclosed in a true tissue cyst,in chronic stage or latent infection when immunity develops .
Oocysts:oval,10x12mm,contains two sporocysts each containing four sporozoites,and found in stools of infected cats

Life cycle

In cats and other felines when cats ingest pseudocyst,cysts,a cycle of schizogony and gametogony takes place in intestinal epithelium with resultant Formation of oocysts that are excreted in stools

In man and other animals : ingestion of pseudocyst or oocysts does not results in an intestinal cycle ,bit exTraintestinal Development brakes place with formation of pseudocyst and cysts in viscera ,muscles and brain

Human infection takes place

Ingestion of undercooked infection meat cysts and paeudocysts

Contamination of water or food with infected cats feces

Transplacental (congential)

Contamination of mucous memberanes with trophozites (laboratory infection)

Pathogenicity
Chronic toxoplasmosis

The commonest form without symptoms,or with chorioretinitis ; detected by the presence of antibodies in the serum.persons with latent from when subjected to immunosuppression from what ever cause (immunosuppressive therapy or infection as aids)may develop acute symptomatic infection

In woman who are infected for first time in first four months of pregnancy,the fetus may become infected.the baby may be aborted or does shortly after birth.live infants show signs of congenital toxoplasmosis: hydrocephalus, encephalitis, chorioretinitis and cerebral classification. Maternal antibodies when present(acquired before pregnancy)protect the fetus

Acute symptomatic toxoplasmosis may present as
Exanthaematous form:typhus fever with rash and enlarged lyumph nodes
Lymphatic form: enlarged lymph nodes ,liver and spleen similar to glandular fever
Cerebrospinal form: meningoencphalitis.

Diagnosis

Frencel intradermal test
Serological tests
Isolation of parasite by inoculation of laboratory animal with biospy Material

Prevention and control

Through cooking of any type of meat. Freezing of meat to -20degree for 2days may kill the cysts.
Care in handling meat
Care in handling cats
Avoid contamination of food and drink with cat feces.oocyts in cat feces can remain infective for a long period.