No abstract

Toxoplasmosis is caused by infection with the protozoan parasite Toxoplasma gondii. In the United States, approximately 85% of women of childbearing age are susceptible to acute infection with T. gondii. Acute infections in pregnant women may cause serious health problems when the organism is transmitted to the fetus (congenital toxoplasmosis), including mental retardation, seizures, blindness, and death. An estimated 400 to 4000 cases of congenital toxoplasmosis occur in the U.S. each year. Manifestations of congenital toxoplasmosis may not become apparent until the second or third decade of life. Serologic tests are used to diagnose acute infection in pregnant women, but false-positive tests occur frequently, therefore, serologic diagnosis must be confirmed at a reference laboratory before treatment with potentially toxic drugs should be considered. Much of congenital toxoplasmosis can be prevented by educating women of childbearing age and pregnant women to avoid eating raw or undercooked meat, to avoid cross-contamination of other foods with raw or undercooked meat, and to use proper cat-litter and soil-related hygiene.

The incidence of placental malaria at parturition and its effects on the conceptus have been investigated in The Gambia, West Africa. Malarious placentae occurred in 1300 (20.2%) of 6427 singleton births, in 32 (18.6%) of 172 sets of twins and in none of six sets of triplets. Plasmodium falciparum infections predominated; P. malariae or P. ovale infections were found in only nine instances. In the large group of single births placental malaria occurred less frequently (12.0%) in residents of urban than of other, more rural, communities (27.1%). In the former group incidence showed no clear change with season; in the latter group it was highest in the trimester following the end of the rains and lowest in the second half of the dry season. In both residential groups it was more frequent in primiparae (urban 16.1%; other 46.9%) than in multiparae (urban 8.9%; other 20.3%). The sex of the child did not influence malaria incidence. Dense placental infections were more frequent in primiparae. Stillbirth rates of singleton infants were significantly higher for males than for females, but no clear and consistent relationship between stillbirth and placental malaria was detected. Mean singleton birthweights were depressed by about 170 g in the presence of malaria; the deficits were statistically significant only among first born infants and tended to diminish progressively with increasing maternal parity. No distinct gradient linking birthweight with ascending density of placental parasitaemia was observed. Singleton birthweights of 2.5 kg or less occurred more frequently in association with malarious than non-malarious placentae and the association was more marked among first born than later birth rank infants. Differences between the weights of malarious and non-malarious placentae were small and not significant. The findings of the study are discussed in relation to the widely prevalent view that pregnancy exacerbates maternal malaria by attenuating acquired immunity.

A diagnosis of neurocysticercosis should be considered in patients with seizures and radiologic evidence of cystic brain lesions, even in those who do not eat pork and who have not traveled to a country in which T. solium infection is endemic. Recent emigrants from countries in which T. solium infection is endemic should be screened for tapeworm infection in their stools before they are employed as housekeepers or food handlers.

Toxoplasma gondii can cause congenital, neurologic, ocular, and mild or asymptomatic infection. To determine the U.S. prevalence of T. gondii infection, we tested sera collected from the National Health and Nutrition Examination Survey (NHANES) 1999-2004 for T. gondii immunoglobulin G antibodies in persons 6-49 years old and contrasted the results to those comparable in NHANES III (1988-1994) (ages 12-49 years). Of the 17,672 persons examined in NHANES 1999-2004, 15,960 (90%) were tested. The age-adjusted T. gondii seroprevalence among persons 6-49 years old was 10.8% (95% confidence limits [CL] 9.6%, 11.9%), and among women 15-44 years old, 11.0% (95% CL 9.5%, 12.4%). T. gondii seroprevalence declined from 14.1% to 9.0% (P < 0.001) from NHANES III to NHANES 1999-2004 among U.S.-born persons ages 12-49 years. Although T. gondii infects many persons in the U.S., the prevalence has declined in the past decade.

Abstract. Strongyloidiasis is a chronic infection that may result in significant morbidity; however, diagnosis and management remain problematic. The objective of this study was to 1) evaluate the demographic, clinical, and laboratory features of 76 consecutive individuals who had Strongyloides stercoralis larvae identified in their fecal specimens; 2) determine the sensitivity of the Centers for Disease Control and Prevention (CDC) enzyme immunoassay (EIA) for detecting antibodies to Strongyloides in those with confirmed infection; and 3) assess the serologic responses and changes in eosinophil counts following treatment. Most (96%) cases occurred in immigrants, but some patients had immigrated as long as 40 years earlier. The CDC Strongyloides EIA had a sensitivity of 94.6% (95% confidence interval ‫ס‬ 92.0-97.2%) in this patient population with proven infection. Serologic and eosinophil counts decreased after therapy, suggesting that they may be useful markers of treatment success.

During the 3 years that the enzyme-linked immunoelectrotransfer blot (EITB) assay for the diagnosis of human cysticercosis has been in use at the Centers for Disease Control, 50 patients with both pathologically confirmed neurocysticercosis and computed tomographic (CT) or magnetic resonance imaging (MRI) scan results were identified. Of 32 patients with two or more lesions, 94% had detectable antibodies by EITB compared with 28% of 18 patients with single lesions. Patients with only calcified cysts (single or multiple) were less likely to have EITB-positive results than were those with noncalcified, enhancing lesions. Antibody was detectable more frequently in serum than in cerebrospinal fluid, regardless of the number or apparent condition of the cysts. These findings confirm that the EITB assay for cysticercosis antibodies is highly sensitive in patients with multiple, enhancing intracranial lesions but is less sensitive in patients with single lesions and in those with calcified lesions.

WA1 is morphologically indistinguishable but antigenically and genotypically distinct from B. microti. Some patients elsewhere who were assumed to have been infected with B. microti may have been infected with WA1. Improved serodiagnostic and molecular techniques are needed for characterizing Babesia species and elucidating the epidemiology of babesiosis, an emergent zoonosis.