The child with congenital toxoplasmosis.
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Biomedical subjects
Publications and source records attributed to C Swisher.
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Muscle biopsies at age 7 months in a set of dizygotic male twins born floppy showed typical features of congenital fiber-type disproportion (CFTD). One of the twins died at age 1 year due to respiratory complications. The second one subsequently developed facial diplegia and external ophthalmoplegia. He never walked, remained wheelchair bound, and required continuous ventilatory support. He underwent repeat biopsies at ages 2 and 4, which showed many atrophic type 1 muscle fibers containing central nuclei and severe type 2 fiber deficiency compatible with centronuclear myopathy (CNM). Two-dimensional gel electrophoresis of muscle showed decreases of type II myosin light chains 2 and 3, suggestive of histochemical type I fiber deficiency. The progressive nature of morphological changes in one of our patients cannot be explained by maturational arrest. Repeat biopsies in cases of CFTD with rapid clinical deterioration may very well show CNM.
Between December 1981 and May 1991, 44 infants and children with congenital toxoplasmosis were referred to our study group. A uniform approach to evaluation and therapy was developed and is described herein along with the clinical characteristics of these infants and children. In addition, case histories that illustrate especially important clinical features or previously undescribed findings are presented. Factors that contributed to the more severe disabilities included delayed diagnosis and initiation of therapy; prolonged, concomitant neonatal hypoxia and hypoglycemia; profound visual impairment; and prolonged, uncorrected increased intracranial pressure with hydrocephalus and compression of the brain. Years after therapy was discontinued, three children developed new retinal lesions (without loss of visual acuity when therapy for Toxoplasma gondii was initiated promptly), and three children experienced a new onset of afebrile seizures. Most remarkable were the normal developmental, neurological, and ophthalmologic findings at the early follow-up evaluations of many--but not all--of the treated children despite severe manifestations, such as substantial systemic disease, hydrocephalus, microcephalus, multiple intracranial calcifications, and extensive macular destruction detected at birth. These favorable outcomes contrast markedly with outcomes reported previously for children with congenital toxoplasmosis who were untreated or treated for only 1 month.
Comparisons of lymphocyte surface phenotypes and functions were made among 25 pediatric patients with congenital toxoplasmosis (ages 1 month to 5 years) and 24 uninfected babies, a baby with postnatally acquired infection, and 6 uninfected, 7 recently infected, and 6 chronically infected adults. Percentages of lymphocytes with B1, T11, T3, T4, T8, T6, B4, Ia, NKH phenotypes and T4 to T8 ratios of infected and uninfected babies were the same (p greater than 0.05). Lymphocytes from congenitally infected babies had lower blastogenic responses (mean stimulation index [SI] = 5) to Toxoplasma lysate antigens (TLA) than lymphocytes from adult control groups with recent and chronic infection (Mean SIs = 32, 72; p less than 0.001). Compared to infected adults, congenitally infected children had similar or greater responses to concanavalin A (mean SIs = 94; 118, 76, p greater than 0.05) and in mixed leukocyte culture (mean SIs = 63; 22, 26, p greater than 0.05). For symptomatic babies, low blastogenic response to TLA correlated with more severe disease at presentation (p = 0.002). Lymphocyte blastogenic responses to TLA were increased for most children when they were older than 15 months, but responses remained less than adult levels for 9 of the 17 older children studied. There was no correlation between concomitant serum pyrimethamine levels and lymphocyte blastogenic responses to TLA. Pyrimethamine and sulfonamide treatment in vitro and in vivo did not alter lymphocyte response to TLA. Lymphocytes from congenitally infected babies failed to produce either gamma interferon or Interleukin 2 when cultured with TLA. In contrast, they produced these lymphokines when cultured with concanavalin A or phytohemagglutinin. Specific deficits in cell-mediated immune responses to TLA may account for the significant organ damage that occurs in infants and children with congenital toxoplasmosis.
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