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EFFECT OF PREVENTIVE MEASURES: The development of reliable routine serology tests and the demonstration of the high prevalence of toxoplasmosis in France led to mandatory prospective screening of pregnant women in 1978, followed by prenatal screening in 1985. In addition, in utero diagnosis, first on fetal blood and now with the reliable and safe method using polymerase chain reaction on amniotic fluid, formally identifies the parasite. THE SITUATION TODAY: A comparison of the experience of a specialized center in Paris during three different periods over the last 40 years showed that currently 71% of all cases of congenital toxoplasmosis are infraclinical at birth and only 5% are severe. Mean incidence of seroconversion during pregnancy is 1.48%, with a 40% risk of fetal contamination if no treatment is given. The risk of overt fetopathy predominantly concerns maternal infections occurring prior to 26 weeks gestation. IN UTERO TREATMENT: Positive PCR diagnosis on amniotic fluid imposes serial ultrasound examinations to identify any fetopathy and an in utero treatment by giving the mother the pyrimethamine-sulfadiazine combination. Biological results are favorable. POST-NATAL TREATMENT: Post-natal treatment is indicated even in latent forms and should be continued for the first year of life. The pyrimethamine-sulfadiazine combination is the only pharmaceutical regimen with well-proven efficacy. New compounds should allow better prophylaxis against maternofetal contamination or improved post-natal treatment. RECURRENCE: In 70% of the cases, serology tests become positive again, but are not associated with significantly increased risk of ocular recurrence.

Objectives: Over a period of 13 years (1982-1995), 49 cases of acquired toxoplasmosis complicated with ocular and/or neurologic or meningeal involvement were observed in our toxoplasmosis laboratory. This series includes 43 cases of isolated ocular lesions, 3 cases of meningoencephalitis (associated with retinochoroiditis in 1 case), 1 case of meningitis with uveitis, 1 case of polyradiculoneuritis and 1 case of facial nerve palsy., Methods: The patients were aged 1 to 62 years. None had either spontaneous or iatrogenic immunodeficiency. There were two steps in the diagnosis. First congenital infection was eliminated on one or several of the following criteria: any possibility of maternal infection during pregnancy ruled out in 26 cases, evidence of recent acquired infection (i.e. clinical and/or serological evidence of recent acquired toxoplasmosis in 17 cases, retinochoroiditis in non-twin siblings in 3 cases). The second step was to confirm the diagnosis of toxoplasma infection. Apart from serological evidence of recent infection, confirmation included specific local antibody synthesis in the aqueous humor of the eye and/or in cerebro-spinal fluid or ocular lesions characteristic of toxoplasmosis and absence of other etiology., Results: Ocular lesions were unilateral in 43 cases among 45. A mean follow-up of 37.9 months revealed relapses in 14 among 36 patients (39%). As routine serological examination for toxoplasmosis is compulsory in France since 1978, it was possible to document retrospectively the immune status of the mothers of many of the patients of the present series during pregnancy and to rule out congenital toxoplasmosis in a number of cases. This might explain the discrepancy between the relatively large number of cases in the present series and the fact that complicated acquired toxoplasmosis has been considered hitherto as relatively rare in immunocompetent patients., Conclusion: Based on the epidemiology of ocular toxoplasmosis and the data obtained here, it is suggested that the acquired pattern of ocular toxoplasmosis might be more frequent than estimated up to now.

Eighty to ninety percent of pathogens responsible for acute respiratory infections in children are viruses, but despite advances in virology these organisms are isolated in only 20 to 45 percent of the cases. Studies conducted outside hospitals have provided epidemiological data. The virus most frequently encountered is the respiratory syncytial virus. The main clinical feature of these respiratory viral infections is obstruction of the bronchioles, and their immediate or delayed danger is the risk of chronic obstructive bronchitis. Treatment is symptomatic, but specific antiviral agents, notably ribavirin, are useful in severe infections.

Among all organ transplantations, those of heart or heart-lung carry the greatest risk of toxoplasmosis. The disease is observed mainly when the donor is seropositive and the recipient seronegative. In these mismatched couples the risk may be as high as 57 percent. Cardiac tissue transplants are responsible for most contaminations. A subclinical serological reactivation can be observed in seropositive recipients. Patent forms are associated with seroconversion in seronegative subjects. Toxoplasmosis is often severe with multivisceral foci; interstitial pneumonia is possible. The serological diagnosis is easy in cases with significant antibody movements, but it may be difficult if the titre is low or stable. The parasitological diagnosis rests on the isolation of toxoplasma in blood, cerebrospinal fluid, bronchoalveolar lavage fluid and cardiac or cerebral biopsy. Immune defence against toxoplasmosis is primarily cellular, with lymphocytosis and inversion of the CD4/CD8 ratio. Macrophages play a crucial role. Interferon-gamma is the major mediator of cellular resistance. In spite of its immunosuppressive action, cyclosporin clearly has an antiparasitic action in vitro and in vivo. A cytomegalovirus infection might facilitate toxoplasma reactivation. Prevention of toxoplasmosis in transplant recipients includes systematic serology of the recipient and, if possible, the donor, detection of mismatched couples and systematic treatment with pyrimethamine of recipients at risk (in seronegative recipients, this drug has reduced the risk from 57 to 14 percent). Cyclosporin should be used as immunosuppressant in preference to other drugs of this kind. Corticosteroids administered in rejections increase the risk of toxoplasmosis.

Five cases of congenital toxoplasmosis consecutive to a maternal toxoplasma infection that had preceded pregnancy were observed. One woman with normal immune system had developed a well-documented lymph node toxoplasmosis 2 months before conceiving. Four women had chronic toxoplasmosis diagnosed in the course of an immunosuppressive disease: Hodgkin's disease in 1 case, systemic lupus erythematosus in 2 cases and pancytopenia in 1 case. Toxoplasmosis had been recognized 3, 5 and 10 years respectively before conception in 3 women, and at an uncertain date in 1 woman. Three women had received corticosteroids during pregnancy, and 2 had undergone splenectomy. Among the 6 children (2 were twins), 1 presented with severe foetal disease at birth, 1 developed lethal systemic toxoplasmosis after birth, 1 showed hydrocephalus with therapeutically well-controlled chorioretinitis, 1 had isolated eye lesion and 2 had asymptomatic infection. The parasite seems to have been transmitted after the 20th week of pregnancy in all cases. The physiopathology of mother-to child toxoplasma transmission, the role played by maternal immunodeficiency and the practical implications of these exceptional cases are discussed.