Differential IFN-γ production by adult and neonatal blood CD56+ natural killer (NK) and NK-like-T cells in response to Trypanosoma cruzi and IL-15.

Early interferon-gamma (IFN-γ) release by innate cells is critical to direct type 1 immune response able to control intracellular pathogens like Trypanosoma cruzi. Although CD56(bright) natural killer (NK) cells are reported to be potent early IFN-γ producers, other CD56(+) cells like CD56(dim) NK cells and NK-like T cells have recently been shown to also release IFN-γ. We have here studied the contribution of each CD56(+) lymphocyte populations in early IFN-γ production in both adults and neonates. On this purpose, we analysed the kinetics of IFN-γ production by RT-PCR, ELISA and flow cytometry from 2 h onwards after T. cruzi and IL-15 stimulation and sought for the responding CD56(+) cells. CD56(bright) and CD56(dim) CD16(-) NK cells were the more potent IFN-γ early producers in response to IL-15 and parasites in adults and neonates. In both age groups, the majority of IFN-γ producing cells were NK cells. However, on the contrary to neonates, CD3(+) CD56(+) NK-like T cells and CD3(+) CD56(-) 'classical' T cells also contributed to early IFN-γ production in adults. Altogether, our results support that whereas NK cells responded almost similarly in neonates and adults, cord blood innate CD56(+) and CD56(-) T cells displayed major quantitative and qualitative defects that could contribute to the well-known neonatal immune immaturity.

Frequency of the congenital transmission of Trypanosoma cruzi: a systematic review and meta-analysis.

BACKGROUND: Chagas disease is caused by the parasite Trypanosoma cruzi and is endemic in much of Latin America. With increased globalisation and immigration, it is a risk in any country, partly through congenital transmission. The frequency of congenital transmission is unclear. OBJECTIVE: To assess the frequency of congenital transmission of T. cruzi. SEARCH STRATEGY: PubMed, Journals@Ovid Full Text, EMBASE, CINAHL, Fuente Academica and BIREME databases were searched using seven search terms related to Chagas disease or T. cruzi and congenital transmission. SELECTION CRITERIA: The inclusion criteria were the following: Dutch, English, French, Portuguese or Spanish language; case report, case series or observational study; original data on congenital T. cruzi infection in humans; congenital infection rate reported or it could be derived. This systematic review included 13 case reports/series and 51 observational studies. DATA COLLECTION AND ANALYSIS: Two investigators independently collected data on study characteristics, diagnosis and congenital infection rate. The principal summary measure--the congenital transmission rate--is defined as the number of congenitally infected infants divided by the number of infants born to infected mothers. A random effects model was used. MAIN RESULTS: The pooled congenital transmission rate was 4.7% (95% confidence interval: 3.9-5.6%). Countries where T. cruzi is endemic had a higher rate of congenital transmission compared with countries where it is not endemic (5.0% versus 2.7%). CONCLUSIONS: Congenital transmission of Chagas disease is a global problem. Overall risk of congenital infection in infants born to infected mothers is about 5%. The congenital mode of transmission requires targeted screening to prevent future cases of Chagas disease.

Chagas disease in European countries: the challenge of a surveillance system.

A study of aggregate data collected from the literature and official sources was undertaken to estimate expected and observed prevalence of Trypanosoma cruzi infection, annual incidence of congenital transmission and rate of underdiagnosis of Chagas disease among Latin American migrants in the nine European countries with the highest prevalence of Chagas disease. Formal and informal data sources were used to estimate the population from endemic countries resident in Europe in 2009, diagnosed cases of Chagas disease and births from mothers originating from endemic countries. By 2009, 4,290 cases had been diagnosed in Europe, compared with an estimated 68,000 to 122,000 expected cases. The expected prevalence was very high in undocumented migrants (on average 45% of total expected cases) while the observed prevalence rate was 1.3 cases per 1,000 resident migrants from endemic countries. An estimated 20 to 183 babies with congenital Chagas disease are born annually in the study countries. The annual incidence rate of congenital transmission per 1,000 pregnancies in women from endemic countries was between none and three cases. The index of under diagnosis of T. cruzi infection was between 94% and 96%. Chagas disease is a public health challenge in the studied European countries. Urgent measures need to be taken to detect new cases of congenital transmission and take care of the existing cases with a focus on migrants without legal residency permit and potential difficulty accessing care.

Globalization of Chagas disease (American trypanosomiasis): the situation in Europe and Belgium.

Trypanosoma cruzi, the protozoan agent of Chagas disease infects ten million people in Latin America where it is the main cause of cardiac failure. It is transmitted by insect vectors in endemic areas, and also congenitally, by transfusion of infected blood, transplantation of infected organs and oral route in both endemic and non-endemic areas. Since the 1990s, a constant decrease of incidence of infection is observed in Latin America, where vector control programmes and improvement of blood banks have been implemented. However, the important migration flows in the last decades for economic reasons have brought considerable numbers of Latin American subjects infected with T. cruzi, in US, Europe, Japan and Australia. Such globalization of T. cruzi infection/Chagas disease has been confirmed in an WHO historical meeting in 2007, emphasizing the importance of a wise management of such patients and the need of implementing control measures in blood banks, transplantation centres and maternities of involved countries in non-endemic areas. This paper considers these elements and the present situation of Chagas disease in Europe and Belgium.

Trichinellosis acquired in Nunavut, Canada in September 2009: meat from grizzly bear suspected.

Five cases of trichinellosis with onset of symptoms in September 2009, were reported in France, and were probably linked to the consumption of meat from a grizzly bear in Cambridge Bay in Nunavut, Canada. Travellers should be aware of the risks of eating raw or rare meat products in arctic regions, particularly game meat such as bear or walrus meat.

[Congenital Chagas disease: from the laboratory to public health]. / Maladie de chagas congénitale: du laboratoire a la santé publique.

Trypanosoma cruzi, the protozoan agent of Chagas disease can be transmitted from mother to foetus. The incidence of congenital infection is estimated to be at least 15,000 cases per year in Latin-America. Its incidence in the non endemic countries (U.S.A., Europe, Japan) is not known. Thanks to multidisciplinary studies performed in Bolivia, it has been possible to specify the epidemiologic and clinical features of congenital Chagas disease. The transplacental route, as well as the role of some parasitic (genotype and parasitic charge) or host factors (capacity of maternal and fetal/neonatal immune responses, particularly the generation of CD8T cells with cytotoxic and IFN-gamma-producing capacities) in mother-to-fetus transmission of infection and/or development of congenital Chagas disease, have been also studied. Altogether, these data have allowed the development of a strategy to control T. cruzi congenital infection, which has been validated by WHO and is applied in various Latin American countries.

Diffuse unilateral subacute neuroretinitis in Africa.

PURPOSE: Diffuse unilateral subacute neuroretinitis (DUSN) is well known in endemic areas of the southeastern United States, South America, and the northern Midwestern United States. Two different categories of nematodes, according to their length, are related to endemic areas. We report the first case of DUSN caused by a small nematode in Africa. METHODS: We describe the case of a 12-year-old Senegalese girl who presented a long-standing diffuse unilateral subacute neuroretinitis and in whom the worm could be localized. RESULTS: The length of the unidentified worm measured using the software of the fundus camera was approximately 600 microm. This measurement corresponds to the smaller nematode usually found in patients from the southeastern United States and South America. CONCLUSION: Diffuse unilateral subacute neuroretinitis can also be observed in patients living in Africa.

Automation of enzyme-linked immunosorbent assay (ELISA).

A prototype of automatized enzyme-linked immunosorbent assay (ELISA) in tubes is described, using a commercially available basic material, easily modified. Nine hundred samples could be completely studied in a day by only one person. The different steps of the automatized ELISA were systematically studied to obtain the best performance. Its application is described in toxoplasmosis serodiagnosis.

Inhibition enzyme immunoassay, application to human apolipoprotein B.

Inhibition enzyme immunoassay was applied to human apolipoprotein B (apo-B) from plasma. The technical conditions of the assay were determined. The detection limits of the assay were 200 ng to 10 microgram/ml. Correlation coefficients obtained between enzymoassay and rocket immunoelectrophoresis on one hand and radial immunodiffusion on the other were respectively 0.84 and 0.80. The inhibition enzymoassay provides a specific and highly sensitive method for the quantitation of apo-B.

Evaluation of circulating antigens by a sandwich radioimmunoassay, and of antibodies and immune complexes, in Schistosoma mansoni-infected African parturients and their newborn children.

Circulating Schistosoma mansoni soluble antigens (CSA), circulating anti-S. mansoni antibodies (CAb), and immune complexes (CIC) were studied in three groups of African patients living in the same area. The first two groups were composed of 26 S. mansoni-infected mothers and their 26 uninfected newborn children. The third group included 13 men and 10 non-pregnant women who were also infected with S. mansoni. CSA were quantified by using a solid phase sandwich radioimmunoassay, which was shown to be sensitive, reproducible, and S. mansoni-specific. CAb were studied by indirect hemagglutination. CIC evaluations were performed by using the Clq binding test. A high correlation was shown between the CSA levels in sera from infected mothers and from the umbilical cord of their newborn children, indicating that CSA are probably transferred through the placenta. CSA levels in mothers were significantly higher than in the third group, in which no difference was found between men and women. On the other hand, CAb and CIC were significantly higher in the third group than in the group of mothers, indicating that CSA levels may be modulated by the immune response of the host.

Immunological studies in human schistosomiasis. II. Antibodies cytotoxic for Schistosoma mansoni schistosomules.

Complement dependent cytotoxic antibodies for Schistosoma mansoni schistosomules were studied in a Brazilian population. The sera of S. mansoni-infected patients gave a high percentage of cytotoxicity (63.4%) compared with sera from persons not infected (8.7%). The IgG class and the specificity of these cytotoxic antibodies are defined. The index of lethality appeared to be independent of the titers of other specific anti-S. mansoni antibodies. A statistical correlation was found between the index of lethality and both the severity of the disease and delayed hypersensitivity to S. mansoni antigen. The significance of cytotoxic antibodies in human schistosomiasis and their relevance to immunity in man are discussed.

Interactions between chronic murine Trypanosoma cruzi infection and pregnancy: fetal growth retardation.

Fetal growth, reproductive capacity, and parasitemia were studied in three groups of BALB/c mice: pregnant and chronically infected with Trypanosoma cruzi, non-pregnant but similarly infected, and pregnant but noninfected. The pregnant mice were killed on day 17 of pregnancy. Comparisons of the two pregnant groups showed significant differences in fetal weights and x18 magnified ossification lengths of radius and cubitus, whereas placental weights were not modified. The results indicate that intrauterine growth retardation occurs during chronic murine T. cruzi infection. No difference was noted between the reproductive capacities of the two pregnant groups. Parasitemias were similar in infected pregnant and control groups. Mice of all groups survived infection until killing. Pregnancy, therefore, does not influence chronic murine T. cruzi infection. Parasites were never found in fetal blood, indicating a very low, if any, frequency of transplacental transmission of parasite during the chronic phase of infection.

Maternal Trypanosoma cruzi-specific antibodies and worsening of acute infection in mouse offspring.

The role of antibodies in the previously demonstrated harmful effect of Trypanosoma cruzi-infected mothers on progeny infection was studied by injecting either serum from chronically infected animals or purified T. cruzi-specific antibodies into uninfected mice during gestation and lactation periods. It was verified that injected antibodies were transferred to offspring. Pregnant or lactating animals exhibited lower circulating antibody levels than nonpregnant or pregnant but nonlactating mice, respectively, suggesting that such antibody transfer occurred in both fetuses and suckling offspring. When infected two months after birth, offspring of mice treated with chronic serum or purified antibodies displayed significantly higher parasitemia than offspring from mothers receiving control serum or immunoglobulins unrelated to T. cruzi. These results indicate that soluble factors contained in sera of infected mice, and particularly antibodies, when transferred from mothers to their young, are able to worsen T. cruzi acquired infection in the offspring.

Direct identification of Trypanosoma cruzi natural clones in vectors and mammalian hosts by polymerase chain reaction amplification.

The polymerase chain reaction was used to amplify the highly variable region of the kinetoplast minicircle of Trypanosoma cruzi directly in biological samples (feces of infected Triatomine bugs, blood samples of experimentally infected mice, and artificially infected human blood samples). Hybridization of the amplified DNAs with reference stocks representing different genotypes (natural clones) enabled us to characterize the stocks infecting the biological samples under study. The main interest of this new approach is the diagnosis of T. cruzi infection and simultaneous direct identification of the different natural clones circulating in vectors and mammalian blood without isolation of the stocks. The suitability of this technique for epidemiologic studies is also discussed.

Immunological studies in human schistosomiasis. III. Immunoglobulin levels, antibodies, and delayed hypersensitivity.

Levels of IgG, IgE, IgM, and IgA were determined, specific antibodies were detected by the fluorescent antibody test, hemagglutination test, complement fixation test and immunoelectrophoresis, and intradermal tests for delayed hypersensitivity to Schistosoma mansoni antigens were performed in Brazilian patients with schistosomiasis mansoni. The results were compared according to the clinical forms of the disease. IgG levels and antibody titers increased progressively in the subclinical, hepatomegalic, and hepatosplenic forms and there was a statistical relationship between IgG levels and the intensity of responses to the four serological tests; Delayed hypersensitivity (DHS) was found more frequently in hepatosplenic patients and more particularly in those with splenomegaly. DHS also correlated with age, but not with sex or with skin color. The strongest DHS reactions were observed in patients 20 to 34 years old, and in those having the highest fecal egg output. IgG levels, antibody titers, and DHS responses decreased after splenectomy and portal filtration of the worms. No significant variation was observed between untreated subjects, patients who were splenectomized and a group not subject to reinfection for 4 yearsk0

Chagas' disease: decreased resistance to Trypanosoma cruzi acquired infection in offspring of infected mice.

The course of Trypanosoma cruzi infection was studied in an experimental model, using the offspring of mice that were chronically infected with T. cruzi. When infected two months after birth, a higher mortality rate in heavily parasitized mice occurred in these offspring than in controls born to uninfected mothers. The harmful maternal influence reached a maximum when offspring were exposed both to prenatal (placental) and postnatal (lactating) influences. It was a reversible phenomenon that led to a T. cruzi-specific failure of the offspring to control the acute phase of the infection. Such features are suggestive of a maternally-induced impairment of the immune response of the offspring.

Specific and sensitive immunological diagnosis of Chagas' disease by competitive antibody enzyme immunoassay using a Trypanosoma cruzi-specific monoclonal antibody.

Coexistence of Chagas' disease with leishmaniasis and T. rangeli infection in endemic areas and cross-reactivity between corresponding etiological agents can confuse the immunodiagnosis of Chagas' disease. A discriminative serological test could therefore represent a major advance in specific immunodiagnosis. A competitive antibody enzyme immunoassay against a component 5-enriched preparation, using a T. cruzi species-specific monoclonal antibody has allowed development of a specific serodiagnosis of Chagas' disease with high sensitivity (96.6% in undetermined and chronic phases of infection). This test can differentiate Chagas' disease from other cross-reacting parasitic diseases in areas where concomitant infections are unknown or suspected.

Detection of Schistosoma mansoni M antigen in circulating immune-complexes and in kidneys of infected hamsters.

Circulating M antigen (CMA) of Schistosoma mansoni was found in the trichloroacetic acid (TCA) soluble fraction of a polyethylene glycol precipitate of serum from infected hamsters. It was also found as a TCA-soluble component in an immunoglobulin-containing fraction eluted from infected hamster kidneys. It was not found in similarly treated control sera nor in the products of acid dissociation of circulating immune complexes (CIC) from infected hamster sera. CMA was not detected in the kidneys of normal hamsters. Precipitating anti-M antigen antibodies were present in one of 10 sera from infected hamsters, but not in the eluates of hamster kidneys. These results indicate that CMA is present in circulating immune complexes in infected hamsters. The presence of CMA in kidneys from the same hamsters suggests a possible role for circulating antigens in immune-complexed form in the aetiology of glomerulonephritis in S. mansoni infection.

Influence of vitamin A on the immune response of Schistosoma mansoni-infected rats.

Nutritional (vitamin A levels, weights), parasitological (adult worm burden, count of eggs in liver, stool examination) and immunological (IgE serum levels, anti-Schistosoma mansoni antibodies, lymphocyte stimulation by concanavalin A and S. mansoni antigenic extract) parameters were studied in three groups of rats, a non-infected and normally fed control group, a S. mansoni-infected but normally fed group, and a S. mansoni-infected group with experimentally induced vitamin A deficiency. The number of worms was found significantly higher in the third (53 +/- 19) than in the second group (2 +/- 2) (p less than 0.001). There were many eggs in the liver surrounded by granulomatous reactions in the third group (399 +/- 73 epg liver). All stool examinations were negative. IgE levels and anti-S. mansoni antibody titres were significantly lower (p less than 0.001) in the third than in the second group. The concanavalin A lymphocyte stimulation indexes did not differ significantly between groups 2 and 3; the S. mansoni lymphocyte stimulation index was only significantly positive in group 3 (p less than 0.001). These results indicate a decrease in the humoral immune response without alteration of cellular immune response in vitamin A-deficient rats infected with S. mansoni.

The use of an excretory-secretory antigen for an ELISA specific sero-diagnosis of visceral larva migrans.

In sera from patients with visceral larva migrans (VLM) syndrome, enzyme-linked immunospecific assay (ELISA) was used to detect IgG and IgE antibody anti-excretory-secretory antigen (ESA) from the second larval stage of Toxocara canis. The technical conditions of the assay were determined. The specificity of IgG ELISA-ESA (with OD values greater than 0.34) allowed the differentiation of VLM syndrome from ascaris or other human parasite infections.