Clinical course of congenital toxoplasmosis in children]

Hundred eleven children with the congenital toxoplasmosis were treated at the Department of Infectious and Parasitic Diseases in Childhood in 1979-1988. Multi-symptomatic toxoplasmosis has been diagnosed in 35 cases, ocular form in 65, oligosymptomatic in 6, and asymptomatic in 5 cases. Clinical symptoms suggesting congenital toxoplasmosis was seen in the majority of children (63 cases) in the first year of life and the disease was diagnosed in 50% of cases (33 children) at this age. Congenital toxoplasmosis in the group of 78 children has been diagnosed later. The majority of cases was ocular form. Diagnosis of the oligo- and asymptomatic congenital toxoplasmosis is possible in the first year of life, only. A titre of antibodies is exclusively an indicator of the immunologic response, not a severity of infection and does not contribute to the prognosis. Antitoxoplasma drugs were administered to 102 children including 33 under the first year of life. Pyrimethamine, sulphonamides, and spiramycin were used in the treatment. Dosage, duration of therapy, and way of administration have been established individually in dependence of patients age and clinical form of the congenital toxoplasmosis. Two out of 35 children with multi-symptomatic congenital toxoplasmosis died whereas 13 demonstrate psychomotor retardation of significant degree despite the fact that 11 of them were treated in the first year of life.     

Congenital transmission of experimental chronic toxoplasmosis in rats.

A 10% transplacental transmission rate was observed in litters from 89 Wistar rats chronically infected with Toxoplasmosis gondii, as judging from bioassays. The rats had been fed T. gondii 2 mo prior to mating. Six of 7 isolates of T. gondii were transplacentally transmitted. The frequency of transmission did not appear to be affected by the strain of T. gondii or the size of the inoculum.     

Observations of children with chorioretinitis in congenital toxoplasmosis]

Hundred eleven children with congenital toxoplasmosis were followed up in the Department of Infectious and Parasitic Diseases in Childhood, Medical Academy in Warsaw, within 1979-1988. Ocular changes found in 91 children including chorioretinitis in 86 microphthalmia in 7, ophthalmic nerve atrophy in 15, vitreous body inflammation in 5, and cataract in 4. Only in 16 children the diagnosis was performed in the first year of life. In 15 children the recurrence of inflammatory process, most frequently in the time of puberty, was noted; twice in 5 of them. It was independent on the treatment which was previously administrated. Serological tests in ocular form of congenital toxoplasmosis do not indicate the dynamic changes in the inflammatory process. It is very important that small children are examined early and the treatment is started in the first year of life.     

Refinement of the mouse model of congenital toxoplasmosis

The goals of the present investigation, focusing on the BALB/c mouse model of congenital toxoplasmosis, were: (1) to find a method to determine pregnancy in the mouse. The method has 100% sensitivity and 72% specificity; (2) to test congenital transmission during the chronic stage of toxoplasmosis. This occurred in 2 of 10 mice tested; (3) to investigate the relationship between the infective dose and the rate of congenital transmission. This was not demonstrated for doses of 10(2) to 10(3) bradyzoites and oocysts of Prugniaud, M3 and M7741 strains, with transmission rates of 3 of 8 to 6 of 10 mice inoculated; (4) to determine homologous and heterologous protection. Homologous protection was demonstrated with Prugniaud cysts, and heterologous protection was found between ME-49 and M3 cysts. This finding is consistent with the uniform natural protection against congenital toxoplasmosis seen in immune women and ewes.     

Western blotting for the diagnosis of congenital toxoplasmosis

Toxoplasmosis is a common congenital infection. It does not usually produce recognizable signs of infection at birth so most infected newborns are not detected by routine clinical examination and remain untreated. Infected children without clinical symptoms should nonetheless be identified and treated as early as possible. Serological diagnosis of congenital toxoplasmosis is quite difficult. The aim of this study was to evaluate the utility of Western blot for the diagnosis of congenital toxoplasmosis. We compared the immunological profiles of mothers and children to differentiate between passively transmitted maternal antibodies and antibodies synthesized by the infants in the first three months of life. The method enabled us to diagnose congenital toxoplasmosis in cases in which the infection had not been detected by classical serology techniques.     

Seasonality of toxoplasmosis]

The indices of seasonal changes in the proportion of population allergopositive to toxoplasmosis were determined by analyzing the results of intracutaneous tests made in 61,324 pregnant women in Novokuznetsk between 1964 and 1974. Indices exceeding the average monthly level were registered in March-July and in September-October. Taking into account the modal term during which allergization develops in a patient from the moment of toxoplasmic invasion, a high risk of toxoplasmosis infection is likely to be present mainly during winter and spring (December-May), as well as summer (July-August) periods. Researchers should pay attention to the nature of the seasonal prevalence of the epidemic process of toxoplasmosis.     

Effect of leucine-enkephalin on the interneuronal transmission of excitation]

In the experiments on non-anesthetized flaxedil-immobilized cats it has been shown that the injection of leucin-enkephalin (1 mg) into the lateral ventricle of the brain is followed by the inhibition of evoked potentials in the ventrolateral columns of the spinal cord and of segmental interneuronal transmission in the spinal cord as well as by the reduction of the amplitude of potentials in the S I zone of the brain cortex induced by the sciatic nerve stimulation. Naloxone (1 mg/kg, i.v.) prevented the effects of leucin-enkephalin. Methysergide pretreatment (2.5 mg/kg, i.p.) led to a decrease of leucin-enkephalin effect on the interneuronal transmission in the spinal cord. Leucin-enkephalin failed to change the amplitude of polysynaptic potentials of glosso-mandibular reflex integrated at the brain stem level.     

Susceptibility of common voles to experimental toxoplasmosis

Common voles (Microtus arvalis) in groups of nine to 10 animals were inoculated per os with a dose of 1, 10, 1x10(2), 1x10(3), and of the K1 strain of Toxoplasma gondii. All the common voles inoculated with 1 to 1 x 10(3) oocysts remained subclinical and survived. Three of the 10 voles inoculated with 1 x 10(4) oocysts died between days 7 and 12 post inoculation (p.i.). Antibodies were demonstrated in all the infected voles killed on day 60 p.i. The highest antibody titres in voles detected by the dye test (DT) and latex agglutination test (LAT) were 1,024 and 1,280, respectively.