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toxoplasmosis

د. هديل فاضل فرهود  

I. Identification : Asystemic protozoan disease, infections are frequently asymptomatics or present as an acute disease with only lymphadenopathy , or one resembling infectious mononucleosis ,  with fever ,lymadenopathy and lymphocytosis persisting for days or weeks .

A primary infection during early pregnancy may lead fetal infection with death of the fetus or chorioretenitis , brain damage with intracerebral calcification , hydrocephaly , microcephaly , fever, jaundice , rash , hepatosplenomegaly , xanthochromic CSF & convulsion at birth or shortly thereafter .

Later in pregnancy , maternal infection results in mild or subclinical fetal disease with delay manifestation , such as recurrent or chronic chorioretinitis .

2- Infectious agent : Toxoplasma gondii .

3- Occurrence : world wide in mammals and birds , infection in human is common.

 4- Reservoir: the definitive hosts of T.gondii are cats which acquire infection mainly from eating infected mammals ( especially rodents ) or bird .

The intermediate hosts of T. gondii include sheep, goat, rodents , cattle, chickens & birds .

5- Mode of transmission :

 *transplacental infection in human ,

 *contact with infected cat ( children may become infected by ingesting infective oocyts by playing with cats have defecated )          

* eating raw meat from infected cattle  & drink milk from infected cattle or goats or by ingestion of infective oocytes  in food or water contaminated with cats  feces   .

* rarely be acquired by blood transfusion or organ transplantation from an infected donor .  

6- Incubation period : from 10-23 days in one common source outbreak from ingestion of undercooked meat , 5-20 days in an outbreak associated with cats .

7- Period of communicability : not directly transmitted from person to person except in utero . Oocyte shed by cats feces  and become infective 1-5 days later and may remain infective in water and soil for over a year.

8- Susceptibility and resistance : susceptibility to infection is general , but immunity is readily acquired and most infections are asymptomatic . duration and degree of immunity are unknown but assumed to be long lasting or permanent , antibodies persist for years, probably for life .

Methods of control

A. Preventive measures :

1- Educate pregnant women about these preventive measures :

     a- use irradiated meats or cook them to 150 F( 66 C ) before eating       freezing meat reduces infectivity but does not eliminate it .

     b- should avoid cleaning litter pans and contact with cats of                  unknown feeding history . Wear gloves during gardening and             wash hand thoroughly after work and before eating .

2- feed cats dry, canned or boiled food and discourage hunting .

3- disposal cat feces and litter daily

4- wash hands thoroughly before eating  and after handling raw meat or having contact with soil possibly contaminated with cat feces .

5- control stray cats  and prevent them from gaining access to areas used by children for play .

B- Control of patient, contact and the immediate environment :

1- report to local health authority : not ordinary required .

2- Isolation : none          3- concurrent disinfection : none

4- Quarantine : none      5- Immunization of contacts : none

6- Investigation of contacts and source of infection : in congenital cases , determine antibody titers in mother , in acquired cases , determine antibody titers in members of the household and common exposure to cat feces , soil , raw meat or infected animals .

7- specific treatment :

 Treatment is not routinely indicated for healthy immunocompetent host , except in an initial infection during pregnancy or the presence  of active chorioretinitis , myocarditis , or other organ involvement  .

Pyrimethamine combined with sulfadiazine and folinic acid ( to avoid bone marrow depression ) for 4 weeks is a preferred treatment for those with sever symptomatic disease .

Clindamycine , in addition to these agents , has been used to treat ocular toxoplasmosis .