Toxoplasmosis during Pregnancy

Toxoplasmosis during Pregnancy

  Autor Aqua Materna Data: 16.05.2005

Toxoplasmosis during Pregnancy
Toxoplasmosis is a zoonosis caused by the protozoan Toxoplasma gondii, and which has two forms is humans: 
  • congenital (severe, with neurological, visual and visceral damages) 
  • acquired (ganglionic, septicemic, visual or even invisible) 
Toxoplasma gondii is part of the genus Toxoplasma, which exists as:
  • trophozoite (invasive, responsible of acute symptoms of the disease) 
  • cyst (responsible for the persistent and latent infection) 
  • oocyst (this exists only in cats, the only animal where the parasite lives a complete life cycle) 
It is sensitive to heat (it dies in 10 minutes at 56 C degrees), to cold (at -20C), it is destroyed by alcohol, phenol, formalin, acids, strong bases).The infection reservoir, the definitive hosts are: the cats which secrete through feces oocysts which become infectious in 5 days, being like this for more months in the wet soil or in the water; the intermediary hosts are: mammals and birds, where the parasites are encysted in different tissues, especially in the muscles and in the brain of the sick human, only in case of placental transmission. 
Digestive transmission: by eating pork, mutton, beef, poultry which contain toxoplasma cysts, or other food contaminated with oocysts eliminated by cats, or contaminated as a result of direct contact with cat feces (dirty hands), or by air (contaminated air), and through placenta: if the infection occurs during pregnancy, through blood or organs transplant. The disease is more frequent in people who work in a zootechnical environment. It has two forms: acquired (adults) and congenital. 

Acquired toxoplasmosis: Most times the disease is latent, and has benign symptoms frequently: cervical, sub-occipital, supraclavicular, axillary, inguinal (small, firm or soft, mobile, unpainful, without puss lymphs); fever, muscle pains, joints pain, headache, rashes; the severe forms usually occur in organism with weakened immunity and they manifest as severe infections with high fever, general bad mood, joint pain, skin rashes, meningoencephalitis, pleuropneumonia, myocarditis, hepatitis. In people with AIDS there might occur a diffuse encephalitis with fast evolution and exitus in a few days. 

Congenital toxoplasmosis. In case the mother gets infected during pregnancy, the infections reaches the placenta and then into the fetal blood. During the first pregnancy trimester the infection is rare but severe, often leading to miscarriage; in the third trimester the infection is frequent but benign. Is the baby is born alive, the disease might be latent, severe or mild. The severe forma manifeststhrough: multi-organs infection, hemorrhagic syndrome, jaundice, hepatosplenomegaly, encephalopathy and fast death or involutive sequelae of a fetal disease with hydro or microcephalus, intracranial calcification. The mild forms are: visual (microphtalmia, cross eye), neurological (hypotonia, transitory drowsiness), liver diseases (jaundice after a few weeks); during the neonatal period, the latent disease manifests later through psychomotor retardation, convulsions, hydroenchephalus. Lab diagnosis. Parasite isolation: from the body fluids, show the acute phase of the disease, while the isolation of the cysts in the tissues, obtained by biopsy is the evidence of a previous infection. 

Dye test (Sabin-Feldman) measures the lgG especially, being sensitive andtypical.
The immunofluorescence indirect reaction measures the same antibodies as the dye test and is largely used in practice. The antibodies which are detectable through these reactions occur in 1-2 weeks after the contamination, reach high titers in 6-8 weeks and decrease after a few months. The low titers may last for a lifetime. The RIF test (Remington) detects the lgM antibodies, it is used for the diagnose of acute infection. The lgM antibodies occur in he first 5 days from contamination and disappear early. Some people who suffer from immunosuppression and from acute toxoplasmosis may not have lgM antibodies, detected by the RIF test. 
ELISA method detects both the lgM and the lgG antibodies. The IDR test with toxoplasmine shows the delayed hypersensitivity reaction; this becomes positive in 3-4 weeks from the contamination and stays like this for the rest of life.  
A dye test or RIF test with titre over 1/1000, a RIF-IgM titre over 1/80 or ELISA IgM over 1/256 detects a recently acquired infection. The diagnosing in pregnant women. The RIF-lgM test or the ELISA lgM are 
done, and if they are positive it means there is an acute infection present. If this is absent, the RIF lgG is done, and repeated after 3 weeks if it is over 1/1000 ; if it is stable, it means the infection is older  than 8 weeks and the risk for the newborn is low. The toxoplasma antigens may also be detected in the amniotic fluid. 

How can we prevent the infection? 
The infection may be prevented by avoiding the contact with pools, dirty soil, by cooking the meat, by washing the hands after touching raw meat, by washing the fruits and vegetables. It is very important to detect the disease in pregnant women, especially in the acute phase. In case of acute infection in the first three months of pregnancy, the surgical abortion is recommended, and after three months, the prevention treatment contains sulfonamides and spiramycin (21 days). 

Toxoplasmosis treatment 
The association of pyrimethamine with sulfadiazine, for a cure of 4-6 weeks in adults with a dose of 100-200 mg of Pyrimetamine in the first day, and 2mg/kg in children for the first 2-3 days; the maintenance dose is of 1 mg/kg, maximum 25 mg per day, taken at every 3-4 days because the Pyrimetamine may cause bone marrow depression, it is associated with folic acid in doses of 6-10 mg per day; the sulfadiazine is taken in doses of 50- 75 mg/kg/per day, in 4 doses. You must ensure a good diuresis to prevent kidney disorders as the side effects are severe; the treatment must be done under medical supervision. 

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