Route of dexamethasone administration influences parasite burden in Strongyloides hyperinfection model

Rodents infected with Strongyloides venezuelensis are experimental models applied to strongyloidiasis research. This study evaluated oral and subcutaneous dexamethasone (DEX) treatments to establish immunosuppression in an experimental model of Strongyloides hyperinfection. Rattus norvegicus Wistar were divided: G I (-): untreated and uninfected animals, G II (+): untreated and infected, G III (o -) orally treated and uninfected, G IV (o +) orally treated and infected, G V (sc -) subcutaneously treated and uninfected, G VI (sc +) subcutaneously treated and infected. For oral administration, DEX was diluted in sterile water (5 µg/ml) and made available to the animals on intervals in experimental days - 5-0, 8-13 and 21-26. For subcutaneous administration, animals received daily injections of DEX disodium phosphate (2 mg/kg). Infection was established by the subcutaneous inoculation of 3000 S. venezuelensis filarioid larvae. Groups were evaluated by egg per gram of feces and parasite females counts and IgG, IgG1 and IgG2a detection. GIV (o +) had egg peaks count on days 13 and 26 and maintained egg elimination until the last experimental day. Parasitic females recovery at day 30 was significantly higher in G IV (o +) when compared to G VI (sc +). Levels of IgG, IgG1 and IgG2a of all groups, except the positive control GII (+), were below the detection threshold. Pharmacological immunosuppression induced by oral administration of DEX produced high parasitic burden, and is a noninvasive method, useful to establish immunosuppression in strongyloidiasis hyperinfection model in rats.

Multiple Stool Sampling and Specific Parasitological Technique are Crucial to Diagnose Strongyloidiasis in Alcoholic Patients

PURPOSE

Chronic alcoholism is a well-known risk factor for strongyloidiasis, in these patients the disease is potentially more severe, probably due to the breakdown of local protective barriers and immunosuppression caused by alcohol, which can lead to autoinfection and dissemination. The aim of this study was to evaluate multiple stool sampling and a specific parasitological assay agar plate culture (APC) for the diagnosis of Strongyloides stercoralis in alcoholics.

METHODS

APC was compared to sedimentation technique (HPJ; Hoffman, Pons and Janer), as parasitological methods to detect S. stercoralis infection in alcoholic individuals. Three stool samples from 60 alcoholic and 60 non-alcoholic individuals were analyzed.

RESULTS

S. stercoralis larvae were observed in 11 (18.3%) alcoholic individuals and 1 (1.7%) nonalcoholic individual (P = 0.0042). In view of the combined results, sensitivity for the APC method was 63.6% (CI 31.6-87.6%) with the first sample reaching 100% (CI 67.8-100%) after analyzing three fecal samples. The HPJ sensitivity was 36.4% (CI 12.4-68.4) in the first sample, reaching 72.7% (CI 39.3-92.7) after three samples analyzed.

CONCLUSION

The present results suggest that in alcoholic patients, it is important to repeat stool sampling with specific techniques, especially using the APC method, to avoid misdiagnosis in cases that could evolve to disseminated strongyloidiasis.

Seropositivity to Cysticercosis in School-Age Children Living in a Low-Income Municipality in the Midwest Region of Brazil

Background

Human cysticercosis (CC) is a global public health problem, especially in Latin America, including Brazil. We aimed to analyze the seroprevalence of CC among school-age children and adolescents.

Methods

We analyzed the presence of specific IgG antibodies against Taenia solium metacestodes in 500 serum samples from elementary school children and adolescents in Jataí City, state of Goiás, Brazil. IgG antibodies against the antigenic extract of the parasite were detected and analyzed by ELISA, and specific peptides were identified by confirmatory Western Blotting test.

Results

Of the 500 study participants, 205 (41%) were male, and 295 (59%) were female. Participants aged between 4 and 18 years (mean age 8.4 years). The percentage of serum samples reactive by ELISA was 37.2%. These samples were analyzed by Western Blotting, which confirmed that the seropositivity rate was 6.2% (95% CI 2.4-14.7) in 31 samples reactive for CC-specific bands, determined in serum samples from 18 male (5-11 years old) and 13 female (4-12 years old) students.

Conclusion

The CC seroprevalence demonstrated in schoolchildren suggests that this parasitosis is endemic in the study area. Further investigations are necessary to clarify the local epidemiology of this parasitosis.

Diagnosis of human strongyloidiasis: Application in clinical practice

This review considers the advantages and disadvantages of parasitological techniques, methods of detecting antibodies and antigens, as well as molecular biology techniques in the diagnosis of human strongyloidiasis. In addition, it elucidates the potential of different techniques for rapid and effective detection of clinical cases, thus enabling early treatment and preventing fatal consequences of this helminthiasis.

Innovative approaches to improve serodiagnosis of Strongyloides stercoralis infection

Strongyloidiasis is a helminthiasis of neglected condition that has no gold standard parasitological diagnosis due to the intermittent release of larvae in feces. This study aimed to use an scFv (single chain variable fragment) obtained by Phage Display, previously validated to detect immune complexes in serum samples from individuals infected with Strongyloides stercoralis by enzyme-linked immunosorbent assay (ELISA). Now the ability of scFv to detect the immune complexes was verified by immunofluorescence, flow cytometry using magnetic beads and surface plasmon resonance (SPR). As ELISA, the SPR, immunofluorescence and flow cytometry demonstrated the ability of scFv to detect immune complexes in sera from individuals with strongyloidiasis and discriminate them from sera of individuals with other parasitic diseases and healthy individuals. Besides de conventional ELISA, the novel approaches can also be promptly applied as auxiliary diagnostic tools to the existing parasitological method for accurate diagnosis of human strongyloidiasis.

Beneficial effects of Strongyloides venezuelensis antigen extract in acute experimental toxoplasmosis

BACKGROUND

Toxoplasma gondii is a protozoan with worldwide distribution and triggers a strong Th1 immune response in infected susceptible hosts. On the contrary, most helminth infections are characterized by Th2 immune response and the use of helminth-derived antigens to regulate immune response in inflammatory disorders has been broadly investigated.

OBJECTIVES

The aim of this study was to investigate whether treatment with Strongyloides venezuelensis antigen extract (SvAg) would alter immune response against T gondii.

METHODS

C57BL/6 mice were orally infected with T gondii and treated with SvAg, and parasitological, histological and immunological parameters were investigated.

RESULTS

It was observed that SvAg treatment improved survival rates of T gondii-infected mice. At day 7 post-infection, the parasite load was lower in the lung and small intestine of infected SvAg-treated mice than untreated infected mice. Remarkably, SvAg-treated mice infected with T gondii presented reduced inflammatory lesions in the small intestine than infected untreated mice and decreased intestinal and systemic levels of IFN-γ, TNF-α and IL-6. In contrast, SvAg treatment increased T gondii-specific IgA serum levels in infected mice.

CONCLUSIONS

S venezuelensis antigen extract has anti-parasitic and anti-inflammatory properties during T gondii infection suggesting as a possible alternative to parasite and inflammation control.

Strongyloides-specific IgA, IgG and IgG immune complex profile in patients with pulmonary tuberculosis

AIMS

To describe an anti-Strongyloides IgA, IgG and IgG immune complex antibody response profile in patients with pulmonary tuberculosis.

METHODS AND RESULTS

Saliva and serum samples were collected from 100 individuals: group I, 50 apparently healthy individuals; and group II, 50 pulmonary tuberculosis patients. The IgA, IgG and IgG immune complex detection were carried out via an ELISA immunoenzymatic test. Optical density medians in saliva samples of IgA antibody (median of 7.21) and IgG-IC (median of 4.95) were significantly higher in tuberculosis group compared to control individuals (median IgA of 3.93 and IgG-IC of 2.38).

CONCLUSION

This study presents antibody data to the field of pulmonary tuberculosis and strongyloidiasis coinfection, including saliva samples, and especially IgG immune complex detection.

Parasitological and immunological aspects of oral and subcutaneous prednisolone treatment in rats experimentally infected with Strongyloides venezuelensis

Strongyloides venezuelensis is a model to study human strongyloidiasis, which infects wild rodents and shares common antigenic epitopes with Strongyloides stercoralis. This study aimed to evaluate parasitological and immunological parameters of prednisolone immunosuppression protocols in rats (Rattus novergicus) infected with S. venezuelensis. Rats were divided into six groups (n = 36): untreated and uninfected (-) or infected (+); oral treatment and uninfected (o-) or infected (o+); subcutaneous treatment and uninfected (sc-) or infected (sc+). For oral immunosuppression, 5 mg/mL of water diluted prednisolone were given five days before infection, and in the days 8 and 21 (for 5 days). For subcutaneous immunosuppression, 10 mg/kg of prednisolone were given daily. The infection was established by the subcutaneous injection of approximately 3,000 S. venezuelensis filarioid larvae per animal. All animals from the (+) and (o+) groups survived, while four rats from the (sc+) died prior to necropsy date. Parasitological analysis showed higher egg elimination in (o+) in comparison to (+) and (sc+) on 7, 13 and 26 days post infection (d.p.i.).The recovery of parasitic females at day 30 was significantly higher in (o+), compared to (+). The (+) and (o+) groups showed a clear increase in anti-S. venezuelensis IgG, IgG1 and IgG2 from 13th d.p.i. Oral immunosuppression led to a higher number of adult females and increased egg output while maintaining IgG and subclasses antibody levels comparable to the positive control.

Immunoreactivity of proteins within 30-40 kDa range during the acute and the recovery phases in rats experimentally infected with Strongyloides venezuelensis

In experimental infection with Strongyloides venezuelensis, the acute and recovery phases can be distinguished, unlike human infections caused by Strongyloides stercoralis. The objective of this study was to evaluate the production of anti-Strongyloides IgG antibodies and the recognition of immunogenic protein bands during the acute and the recovery phases in rats experimentally infected with S. venezuelensis. Rats were infected subcutaneously with 400 or 4,000 S. venezuelensis infective larvae. The acute phase was characterized by elimination of a large number of eggs in the faeces on days 6-14 post infection; the recovery phase was characterized by the resolution of the infection between days 30 and 35 post infection. Differences in IgG levels were observed in the acute and the recovery phases. Different antigenic fractions were recognized in both phases of infection. It is concluded that proteins within the 30-40 kDa range are immunoreactive markers for both the acute and the recovery phases in rats experimentally infected with S. venezuelensis, particularly using membrane antigen.

The Anthelmintic Effect on Strongyloides venezuelensis Induced by BnSP- 6, a Lys49-phospholipase A2 Homologue from Bothrops pauloensis Venom

Background:

Phospholipases A2 (PLA2) from snake venoms have a broad potential as pharmacological tools on medicine. In this context, strongyloidiasis is a neglected parasitic disease caused by helminths of the genus Strongyloides. Currently, ivermectin is the drug of choice for treatment, however, besides its notable toxicity, therapeutic failures and cases of drug resistance have been reported. BnSP-6, from Bothorps pauloensis snake venom, is a PLA2 with depth biochemical characterization, reporting effects against tumor cells and bacteria.

Objective:

The aim of this study is to demonstrate for the first time the action of the PLA2 on Strongyloides venezuelensis.

Methods:

After 72 hours of treatment with BnSP-6 mortality of the infective larvae was assessed by motility assay. Cell and parasite viability was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Furthermore, autophagic vacuoles were labeled with Monodansylcadaverine (MDC) and nuclei of apoptotic cells were labeled with Propidium Iodide (PI). Tissue degeneration of the parasite was highlighted by Transmission Electron Microscopy (TEM).

Results:

The mortality index demonstrated that BnSP-6 abolishes the motility of the parasite. In addition, the MTT assay attested the cytotoxicity of BnSP-6 at lower concentrations when compared with ivermectin, while autophagic and apoptosis processes were confirmed. Moreover, the anthelmintic effect was demonstrated by tissue degeneration observed by TEM. Furthermore, we report that BnSP-6 showed low cytotoxicity on human intestinal cells (Caco-2).

Conclusion:

Altogether, our results shed light on the potential of BNSP-6 as an anthelmintic agent, which can lead to further investigations as a tool for pharmaceutical discoveries.

In vitro ovicidal and larvicidal activity of Carica papaya seed hexane extract against Strongyloides venezuelensis

Strongyloidiasis is a human parasitic disease caused by the helminth Strongyloides stercoralis whose treatment is particularly difficult in immunosuppressed patients due to their low responsiveness to conventional therapy. Carica papaya and its isolated compounds benzyl isothiocyanate, carpaine and carpasemine are promising compound for the treatment of Strongyloides infections due to their anthelmintic action. This study aims to examine the in vitro ovicidal and larvicidal activity of C. papaya seed hexane extract against Strongyloides venezuelensis, using egg hatching tests and larval motility tests as efficiency markers. The crude extract at the concentrations of 566 - 0.0566 mg/mL or the control with albendazole (0.025 mg/mL) and negative controls (water and PBS) were incubated with an equal volume of egg suspension (± 50 specimens) followed by counting of the specimens after 48 h. The same extract and dilutions were added to L3 larvae suspensions (±50 specimens) followed by analysis of larvae viability after 24, 48, and 72 h. The extract inhibited egg hatching with high efficiency at concentrations of 56.6 mg/mL (95.74%) and 5.66 mg/mL (92.16%). At the concentrations of 566 mg/mL (100%) and 56.66 mg/mL (97.32%), the extract inhibited larval motility as effectively as ivermectin (0.316 mg/mL; 100%), and more effectively than the other dilutions and the negative controls. The larvicidal effect depended on the extract concentration, but not on the treatment period. Therefore, C. papaya seed hexane extract has anthelmintic potential against S. venezuelensis and is a promising compound for the development of phytotherapies to treat strongyloidiasis.

Seroepidemiological aspects of human infection by Strongyloides stercoralis in Alfenas, southern Minas Gerais, Brazil

INTRODUCTION

In most Strongyloides stercoralis infected individuals, nematoidosis occurs asymptomatically, but in immunocompromised patients, it can cause hyperinfection. Serological techniques seem to be a good alternative for detecting this parasite.

METHODS

The frequency of seropositivity for strongyloidiasis in Alfenas, MG, was estimated using the enzyme linked immunosorbent assay on blood samples, between May and August of 2015.

RESULTS

Out of 258 samples tested, 53.9% were positive, and the frequency of seropositive individuals was higher in the peripheral districts of the municipality.

CONCLUSIONS

The results indicate high seropositivity rates for strongyloidiasis among the residents of Alfenas city.

Inducible nitric oxide synthase controls experimental Strongyloides infection

Infection with Strongyloides sp. induces a host immune response, predominantly the Th2 type, that is able to eliminate the parasite. However, little is known about the role of the nitric oxide (NO) mediator, induced by the enzyme nitric oxide synthase (NOS), in strongyloidiasis. Therefore, in this study, we investigated the immune response of mice genetically deficient in the enzyme inducible nitric oxide synthase (iNOS^-/- ), infected with Strongyloides venezuelensis. C57BL/6 wild-type (WT) and iNOS^-/- mice were individually inoculated by subcutaneous injection of 3000 S. venezuelensis L3 larvae. In the absence of iNOS, mice were more susceptible to the infection than WT animals, in which the parasite was completely eliminated. The overall production of cytokines and specific IgG, IgG1 or IgE antibodies against the parasite was significantly lowered in infected iNOS^-/- mice. The expression of iNOS was observed in the intestine of WT hosts but mainly in the wall of the parasite, despite the presence of iNOS in mice. Altogether, we concluded that iNOS expression may play an important role in the control of S. venezuelensis infection.

Metaperiodate deglycosylation of Strongyloides venezuelensis larvae: Immunochemical characterization and antigen production for human strongyloidiasis diagnosis

Strongyloidiasis is an important helminthiasis affecting million people worldwide. The aim of this study was to use sodium metaperiodate (MP) treatment to immunochemically characterize Strongyloides venezuelensis filariform larvae and use MP-treated heterologous antigen to detect IgG and subclasses in serum. Samples from individuals with definitive diagnosis of strongyloidiasis (n = 50), other parasitic diseases (n = 60) and negative endemic (n = 50) were tested. TG-ROC and two-way ANOVA were applied. MP-treatment resulted on differential localization of carbohydrates at larval structure and no carbohydrate content in saline extract (SE). Electrophoretic profiles were similar before and after treatment. ELISA sensitivity and specificity were: 90%; 88.2% for SE and 92.0%; 94.6% for MP, respectively. When using MP treated antigen we observed reduction in IgG1 and IgG3 detection in strongyloidiasis group and decrease of cross reactions in control groups. Our data demonstrate the role of carbohydrate residues in cross reactions and on the recognition of anti-Strongyloides IgG and its subclasses.

Seroprevalence of human cysticercosis in Jataí, Goiás state, Brazil

The Taenia solium cysticercosis affects millions of people worldwide and is considered a public health problem, especially in developing countries. The diagnosis of neurocysticercosis is complex and involves the analysis of epidemiological, clinical, neuroimaging, and immunological host data. Neurocysticercosis is endemic in Brazil, and is related to the cause of death mainly in the Southeast, South, and Central-West regions. The objective of this study was to determine the seroprevalence of cysticercosis in inhabitants of the city of Jataí, Goiás, in the Central-West region of Brazil from April to August 2012. A total of 529 serum samples were analyzed by enzyme-linked immunosorbent assay for detecting IgG antibodies against T. solium larvae, and Western blotting was used for confirming the diagnosis through the recognition of at least two specific peptides from their serum antibodies. The 351/529 (66.3%) reactive samples were analyzed by enzyme-linked immunosorbent assay and Western blotting confirmed the diagnosis in 73 samples that recognized at least two of the following peptides specific IgG antibodies for cysticercosis: 18, 24, 28-32, 39-42, 47-52, 64-68, and 70kDa. The seroprevalence of cysticercosis was 13.8% (95% CI 5.9-21.7), demonstrating that the studied area is endemic to this disease.

In vitro efficacy of latex and purified papain from Carica papaya against Strongyloides venezuelensis eggs and larvae

Latex from Carica papaya is rich in bioactive compounds, especially papain, which may help to control parasitic diseases. This study evaluated the efficacy of latex from C. papaya and purified papain against Strongyloides venezuelensis. The Egg Hatching Test (EHT) and the Larval Motility Test (LMT) using fresh and frozen latex (250mg/mL), lyophilized latex (34mg/mL), and purified papain (2.8 mg/mL) were performed. Albendazole (0.025 mg/mL) and ivermectin (316 ppm) were used as positive controls. EHT and LMT were carried out through the incubation of each solution with S. venezuelensis eggs or larvae (± 100 specimens), and results were analyzed after 48h (EHT) or 24, 48, and 72h (LMT). EHT showed that latex preparations at higher concentrations (1:10 to 1:100) resulted in partial or complete destruction of eggs and larvae inside the eggs. The result from the 1:1,000 dilution was similar to the positive control. LMT showed effectiveness in all the tested dilutions compared to negative controls. Purified papain showed a dose-dependent response in the EHT. Purified papain (2.8 mg/ mL) showed similar results to lyophilized latex at 1:1,000 in the EHT. Latex and purified papain from C. papaya were effective against S. venezuelensis eggs and larvae in vitro, suggesting their potential use as an alternative treatment for strongyloidiasis.

Detection of parasite-specific IgG and IgA in paired serum and saliva samples for diagnosis of human strongyloidiasis in northern Paraná state, Brazil

Human strongyloidiasis is an infection caused by the helminth Strongyloides stercoralis that can be fatal, especially in immunosuppressed patients. The aim of this study is to evaluate parasite-specific IgG and IgA levels using S. venezuelensis third-stage (L3) infective larvae alkaline extract as a heterologous antigen by ELISA in paired serum and saliva samples with improved sensitivity and specificity. Individuals from northern Paraná state, Brazil were divided into three groups: 30 patients copropositive for S. stercoralis (Group I); 30 clinically healthy individuals (Group II); and 30 patients copropositive for other parasites (Group III). The area under ROC curve (AUC), an overall index of diagnostic accuracy, and Kappa index were calculated. Data were analyzed using analysis of variance (ANOVA) followed by a Kruskal-Wallis test. Probability (p) values of <0.05 were regarded as significant. In Group I, IgG was detected in 96.7% serum and in 6.7% saliva samples. IgG was not detected in Group II. In Group III, cross-reactivity was observed for serum IgG in 26.7% and in 6.7% for saliva samples. In Group I, IgA was detected in 76.7% serum and 56.7% saliva samples. In Group II, 3.3% were positive for IgA in serum, whereas IgA was not detected in any saliva samples. Group III showed 6.7% serum and 26.7% saliva-positive samples. The sensitivity values for detection of IgG and IgA in serum samples were 96.7% and 76.7%, respectively. In saliva samples, the sensitivity values for detection of IgG and IgA were 6.7% and 56.7%, respectively. The specificity value was 100% for the detection of IgG in serum and for detection of IgG and IgA in saliva, and 96.7% for detection of IgA in serum samples. The proper choice of immunological diagnosis to supplement parasitological methods is essential to estimate the true prevalence of the parasite, and will permit analysis of population immune response profiles, particularly in northern Paraná state, where there are no previous reports.

Bacteriophage-fused peptides for serodiagnosis of human strongyloidiasis

Background

Strongyloidiasis, a human intestinal infection caused by the nematode Strongyloides stercoralis, is frequently underdiagnosed and although its high prevalence is still a neglected parasitic disease because conventional diagnostic tests based on parasitological examination (presence of Strongyloides larvae in stool) are not sufficiently sensitive due to the low parasitic load and to the irregular larval output. There is an urgent need to improve diagnostic assays, especially for immunocompromised patients with high parasitic load as consequence of self-infection cycle, which can disseminate throughout the body, resulting in a potentially fatal hyperinfection syndrome often accompanied by sepsis or meningitis.

Methods/Principal Findings

We have performed Phage Display technology to select peptides that mimic S. stercoralis antigens, capable of detecting a humoral response in patients with strongyloidiasis. The peptides reactivity was investigated by Phage-ELISA through different panels of serum samples. We have successfully selected five peptides with significant immunoreactivity to circulating IgG from patients' sera with strongyloidiasis. The phage displayed peptides C9 and C10 presented the highest diagnostic potential (AUC>0.87) with excellent sensitivity (>85%) and good specificity (>77.5%), suggesting that some S. stercoralis antigens trigger systemic immune response.

Conclusions/Significance

These novel antigens are interesting serum biomarkers for routine strongyloidiasis screenings due to the easy production and simple assay using Phage-ELISA. Such markers may also present a promising application for therapeutic monitoring.

Strongyloidiasis is one of the most neglected helminthic infections and can cause disseminated disease in immunocompromised hosts, which can be fatal. Given the unsatisfactory results of current parasitological and serological tests, there is a need for more efficient diagnostic tools. Therefore we have used phage display technology and bioppaning procedure to select sensitive and specific mimotopes ready to be used in immunodiagnostic tests. These mimotopes allows a cheap and fast clear-cut diagnosis of Strongyloides stercoralis infections. The field applicability of the assay using the phage clones obtained is really promising. The main advantage is that phage-based ELISA is the reproducible, simple, rapid and low-cost for production of recombinant antigens, and such tests may be of interest for massive screening in developing countries. Our results indicate that the mimotopes selected and tested here are potential biomarkers for the diagnosis of human strongyloidiasis.

High prevalence of Strongyloides stercoralis infection among the elderly in Brazil

Little is known about the frequency of intestinal parasites in the elderly due to a lack of attention given to the occurrence of these infections among older adults. This study compares the frequency of Strongyloides stercoralis and other enteroparasites between elderly living in nursing homes (n = 100) and those noninstitutionalized (n = 100) from Uberlândia, state of Minas Gerais, southeastern Brazil, associated with data of epidemiological and socio-demographic conditions. Through coproparasitological examination of both groups, enteroparasites were detected in 15 of 200 individuals examined (7.5%; CI: 5.1- 9.9). S. stercoralis was the most frequent parasite 10/200 (5%; CI: 4.2-5.8), being significantly higher in males and in individuals with autonomy for daily living activities. There were no statistical differences in the prevalence of parasites between the two groups compared. In conclusion, S. stercoralis infection was highly prevalent in elderly patients and it does not depend on whether the individual was institutionalized or not.

Increased susceptibility to Strongyloides venezuelensis infection is related to the parasite load and absence of major histocompatibility complex (MHC) class II molecules

In human and murine models strongyloidiasis induce a Th2 type response. In the current study we investigated the role of different loads of Strongyloides venezuelensis in the immune response raised against the parasite and the participation of the major histocompatibility complex (MHC) class II molecule in the disease outcome in face of the different parasite burden. The C57BL/6 wild type (WT) and MHC II(-/-) mice were individually inoculated by subcutaneous injection with 500 or 3000 S. venezuelensis L3. The MHC II(-/-) mice infected with 3000L3 were more susceptible to S. venezuelensis infection when compared with WT groups, in which the parasite was completely eliminated. The production of Th2 cytokines and specific IgG1 or IgE antibodies against parasite were significantly lowered in MHC II(-/-) infected mice with different larvae inoculums. The infection of MHC II(-/-) mice with S. venezuelensis induced slight inflammatory alterations in the small intestine, and these lesions were lower when compared with WT mice, irrespective of the parasite load utilized to infect animals. Finally, we concluded that MHC class II molecules are essential in the immune response against S. venezuelensis mainly when infection occurs with high parasite inoculum.

Serodiagnosis of human neurocysticercosis using antigenic components of Taenia solium metacestodes derived from the unbound fraction from jacalin affinity chromatography

The aim of the present study was to analyse Taenia solium metacestode antigens that were derived from the unbound fraction of jacalin affinity chromatography and subsequent tert-octylphenoxy poly (oxyethylene) ethanol Triton X-114 (TX-114) partitioning in the diagnosis of human neurocysticercosis (NCC). Immunoassays were designed to detect T. solium-specific IgG antibodies by ELISA and immunoblot. Serum samples were collected from 132 individuals who were categorised as follows: 40 had NCC, 62 presented Taenia spp or other parasitic diseases and 30 were healthy individuals. The jacalin-unbound (J unbound ) fraction presented higher sensitivity and specificity rates than the jacalin-bound fraction and only this fraction was subjected to subsequent TX-114 partitioning, resulting in detergent (DJ unbound ) and aqueous (AJ unbound ) fractions. The ELISA sensitivity and specificity were 85% and 84.8% for J unbound , 92.5% and 93.5% for DJ unbound and 82.5% and 82.6% for AJ unbound . By immunoblot, the DJ unbound fraction showed 100% sensitivity and specificity and only serum samples from patients with NCC recognised the 50-70 kDa T. solium-specific components. We conclude that the DJ unbound fraction can serve as a useful tool for the differential immunodiagnosis of NCC by immunoblot.

Taenia saginata metacestode antigenic fractions obtained by ion-exchange chromatography: potential source of immunodominant markers applicable in the immunodiagnosis of human neurocysticercosis

The aim of this study was to fractionate and partially characterize fractions obtained from the total saline extract (SE) of Taenia saginata metacestodes after ion-exchange procedure in carboxymethyl sepharose (CM) and diethylaminoethyl sepharose (DEAE) resins, as a source of antigenic markers applicable in the immunodiagnosis of neurocysticercosis (NCC). For IgG detection by enzyme-linked immunosorbent assay (ELISA) and immunoblotting, 140 serum samples were analyzed: 45 from patients with NCC (G1), 50 from patients with other parasitic infections (G2), and 45 from healthy individuals. Sensitivity (Se), specificity (Sp), area under curve (AUC), and likelihood ratios (LR) were calculated. CM S2 and DEAE S2 fractions provided high diagnostic values (Se 88.8% and 93.4%; Sp 93.7% and 92.6%; AUC 0.965 and 0.987; LR+ 14.07 and 12.67; LR- 0.11 and 0.07, respectively). In conclusion, CM S2 and DEAE S2 fractions are important sources of specific peptides, with high efficiency to diagnose NCC.

Genetic polymorphism in Taenia solium metacestodes from different Brazilian geographic areas

The aim of the present study is to investigate genetic polymorphisms in Taenia solium metacestodes from different Brazilian geographical areas and to relate them to antibody recognition in serum samples of neurocysticercosis (NC) patients. Metacestodes were obtained from the Distrito Federal (DF), Bahia, Minas Gerais (MG) and São Paulo (SP) regions of Brazil. Samples of human sera from 49 individuals with NC, 68 individuals with other helminthiasis and 40 healthy volunteers were analysed (157 individuals in total). Antigens were prepared and used in enzyme-linked immunosorbent assay and western blotting assays to detect specific immunoglobulin G antibodies. Genetic distances between metacestode populations were analysed using random amplified polymorphic DNA (RAPD) analysis. Our results show that there was a higher frequency of reactivity in the DF region in the sera from NC patients (p < 0.05), while discrimination between active and inactive NC was seen only in extracts from the MG and SP regions (p < 0.05). Using RAPD, the sample from the DF region presented a greater increase compared to the other regions. A relationship between genetic polymorphisms among T. solium metacestodes from different areas in Brazil and the differences in antibody detection in patients with NC were established.

Specific phage-displayed peptides discriminate different forms of neurocysticercosis by antibody detection in the serum samples

Neurocysticercosis (NC), caused by Taenia solium metacestode, infects the central nervous system and is a devastating parasitic infection. Diagnosis is based on symptoms, imaging, serology and epidemiology. Current markers present variable sensitivity and specificity, frequent cross-reactions and are not able to discriminate NC clinical forms. The aim of this study was to select mimotopes of T. solium metacestode antigens that may be used in NC immunodiagnosis, specifically to discriminate between active and inactive forms. A random peptide phage display library was screened against IgY from chickens immunized with total saline extract from T. solium metacestodes and validated against 110 serum samples, classified into active NC (18), inactive NC (22), cross-reactive parasitic diseases (40) and healthy controls (30). We have successfully selected seven peptides with significant immunoreactivity to IgG of NC patients, with sensitivity ranging from 95.5% to 100% to detect the inactive form and specificity varied from 85.7% to 94.3%. One phage-displayed peptide (Cc48) can be directly used as biomarker to distinguish inactive from active forms with an accuracy of 95.7%, and this novel mimotope may also be used as an auxiliary tool to neuroimaging tests and treatment follow-up.

Hydrophobic fraction of Taenia saginata metacestodes, rather than hydrophilic fraction, contains immunodominant markers for diagnosing human neurocysticercosis

INTRODUCTION

Considering that alternative antigens for diagnosing neurocysticercosis continue to be a challenge because of the increasing difficulty in obtaining parasites from naturally infected pigs for preparation of Taenia solium homologous antigen, the aim of the present study was to evaluate the detergent (D) and aqueous (A) fractions from saline extract of Taenia saginata metacestodes for diagnosing neurocysticercosis.

METHODS

Taenia saginata was obtained from naturally infected bovines in the Triângulo Mineiro region, State of Minas Gerais, Brazil. The carcasses came from cold storage units and had been slaughtered in accordance with the inspection technique recommended by the Federal Inspection Service. The D and A fractions were obtained by using Triton X-114 (TX-114). Serum samples were obtained from 40 patients with a diagnosis of neurocysticercosis, 45 with other parasitic diseases and 30 from apparently normal individuals. IgG antibody levels were evaluated using the ELISA and immunoblotting assays.

RESULTS

The ELISA sensitivity and specificity were 95% and 73.3%, when using saline extract; 95% and 82.6% for the D fraction; and 65% and 61.3% for the A fraction, respectively. The immunoblotting assay confirmed the ELISA results, such that the D fraction was more efficient than the other extracts, and the 70-68 kDa component was immunodominant among neurocysticercosis patients.

CONCLUSIONS

These results demonstrated that the D fraction from Taenia saginata metacestodes obtained using TX-114 can be used as a heterologous antigenic fraction in the immunoblotting assay for serologically diagnosing human neurocysticercosis, given its ability to select immunodominant antigens.

Hydrophobic fractions from Strongyloides venezuelensis for use in the human immunodiagnosis of strongyloidiasis

The objective of the present research was to evaluate detergent and aqueous phases of total saline (TS) and alkaline extracts of Strongyloides venezuelensis for human strongyloidiasis immunodiagnosis. Total extracts and detergent and aqueous antigenic fractions were separated using Triton X-114 and were examined by enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB) tests to detect immunoglobulin G (IgG). Serum samples were obtained from 120 individuals: 40 strongyloidiasis patients (group I), 40 patients with other parasitic diseases (group II), and 40 apparently healthy individuals (group III). Each extract provided a different profile of antigenic components as recognized by IgG in IB. The detergent fraction of the TS extract demonstrated the highest sensitivity and specificity for ELISA and IB. The results indicated that the detergent saline fraction, purified from S. venezuelensis, furnished the most valid results for the strongyloidiasis immunodiagnosis and could be employed as an alternative antigen and as a useful source of specific polypeptides.

Occurrence of positivity for Trypanosoma cruzi in triatomine from municipalities in Southeastern Brazil, from 2002 to 2004

INTRODUCTION: from an epidemiological point of view, more than 120 species of triatomine (Hemiptera, Reduviidae) are known. The occurrence and positivity for Trypanosoma cruzi in triatomines in 16 municipalities of the Triângulo Mineiro and Alto Paranaíba were evaluated from January 2002 to December 2004. METHODS: the triatomines were captured basically according to the classic norms of the National Health Foundation. The parasitological exams of the triatomines were conducted according to the technique described by the Ministry of Health. During the study period, 990 specimens of triatomines were captured and of these, 771 could be examined. RESULTS: five species were identified: Triatoma sordida, Panstrongylus diasi, Panstrongylus megistus, Panstrongylus geniculatus and Rhodnius neglectus. Triatoma sordida represented 71.5% of all the triatomines captured, followed by Panstrongylus megistus (18%), Rhodnius neglectus (9.3%), Panstrongylus diasi (0.8%) and Panstrongylus geniculatus (0.4%). Of the total number of triatomines examined, 2.7% were positive for Trypanosoma cruzi. Panstrongylus megistus was the species that presented the highest rates of infection by Trypanosoma cruzi (8.3%), followed by Rhodnius neglectus (2.9%) and Triatoma sordida (1.4%). CONCLUSIONS: there is a need to adapt to new circumstances in epidemiology, with greater emphasis on entomological surveillance, since the potential for adaptation of secondary species of triatomines exists, especially where Chagas' disease is already under control.

Enteroparasites and commensals among children in four peripheral districts of Uberlândia, State of Minas Gerais

The aim of this study was to determine the occurrence of intestinal parasites and commensals among children in four peripheral districts located in the northern, southern, eastern and western sectors of Uberlândia, Minas Gerais, using the Baermann methods as modified by Moraes and Lutz. Out of 160 individuals studied, 93 (58.1% CI: 50.4-65.7) were infected, distributed among the sectors as follows: northern (72.5%), southern (47.5%), eastern (57.5%) and western (55%). The positive findings according to age groups were: 0-5 years (26.9%), 5-10 years (21.2%) and 10-15 years (10%). Male children presented 2.7 times higher risk of infection than females did (OR: 2.7; CI: 1052-7001). The parasites and commensals identified were: Giardia lamblia (27.5%), Entamoeba coli (20.6%), Ascaris lumbricoides (14.4%), Enterobius vermicularis (8.8%), Hymenolepis nana (7.5%), Hymenolepis diminuta (5%), hookworms (3.1%), Trichuris trichiura (2.5%), Endolimax nana (2.5%), Entamoeba hartmanni (2.5%), Strongyloides stercoralis (1.3%), Iodamoeba butschlii (1.3%) and Capillaria hepatica (0.6%). The infection rate in these children was high and showed the need to implement prophylactic education programs in the community.

Immunolocalization and pathological alterations following Strongyloides venezuelensis infection in the lungs and the intestine of MHC class I or II deficient mice

The present study, investigated the mechanisms involved in the immune responses of Major Histocompatibility Complex class I or class II knockout mice, following Strongyloides venezuelensis infection. Wild-type C57BL/6 (WT), MHC II(-/-) and MHC I(-/-) mice were individually inoculated with 3000 larvae (L3) of S. venezuelensis and sacrificed on days 1, 3, 5, 8, 13 and 21 post-infection (p.i.). Samples of blood, lungs and small intestines were collected. The tissue samples were stained with hematoxylin-eosin for the pathological analysis. The presence of the parasite was demonstrated by immunoperoxidase analysis. MHC II(-/-) mice presented a significantly higher number of adult worms recovered from the small intestine on day 5p.i. and presented elevated numbers of eggs in the feces. The infection by S. venezuelensis was completely eliminated 13 days after infection in WT as well as in MHC I(-/-) mice. In MHC II(-/-) mice, eggs and adult worms were still found on day 21 p.i., however, there was a significant reduction in their numbers. In the lung, the parasite was observed in MHC I(-/-) on day 1 p.i. and in MHC II(-/-) mice on days 1 and 5 p.i. In the small intestine of WT mice, a larger number of parasites were observed on day 8 p.i. and their absence was observed after day 13 p.i. Through immunohistochemistry analysis, the parasite was detected in the duodenum of WT on days 5 and 8 p.i., and in knockout mice on days 5, 8 and 13 p.i.; as well as in posterior portions of the small intestine in MHC I(-/-) and MHC II(-/-) on day 13 p.i., a finding which was not observed in WT mice. We concluded that immunohistochemistry analysis contributed to a more adequate understanding of the parasite localization in immunodeficient hosts and that the findings aid in the interpretation of immunopathogenesis in Strongyloides infection.

Taenia solium metacestode immunodominant peptides recognized by IgG antibodies in cerebrospinal fluid and serum paired samples from patients with active and inactive neurocysticercosis

The aim of this study was to test if serological distinction between patients with active and inactive neurocysticercosis (NCC), could be accomplished by the recognition of immunodominant peptides in total saline antigenic extract of Taenia solium metacestodes by IgG antibody in cerebrospinal fluid (CSF) and serum paired samples. CSF and serum samples of 10 each, active NCC patients, inactive NCC, and individuals with other neurological disorders, were used to recognize the antigenic peptides by western blot (WB). In the active NCC the 28-32 and 39-42 kDa peptides were more frequently detected in CSF than in sera (p < 0.05). The 47-52, 64-68, and 70 kDa antigens showed high frequencies in both samples from patients with active NCC. All the CSF samples of inactive NCC and other neurological disorder (control) patients tested negative, while serum samples from these last two groups recognized mainly the 80, 86, 95, and 98 kDa bands. This finding eliminates the use of the high molecular weigh bands (>or= 80 kDa) for diagnosis of NCC. The final conclusions were that the difference between active and inactive NCC may be done with the detection of peptides only in the CSF samples and that the 47-52, 64-68, and 70 kDa bands may be included as specific markers for active NCC when detected in CSF samples by WB using total saline extract of T. solium metacestode.

Evaluation of strongyloidiasis in kennel dogs and keepers by parasitological and serological assays

Strongyloides stercoralis is an intestinal nematode with worldwide distribution, particularly in tropical and subtropical regions. Due to the low sensitivity of traditional parasitological methods, the detection of serum specific antibodies may serve as an alternative test for the diagnosis. The aims of the present study were to verify the occurrence of S. stercoralis and the presence of specific IgG antibodies to the parasite in kennel dogs and keepers, using parasitological and serological assays. A total of 181 dogs were examined from 7 breeding kennels in the city of Uberlândia, southeastern region of Brazil and distributed as follows: kennel A (n=41), kennel B (n=16), kennel C (n=11), kennel D (n=63), kennel E (n=11), kennel F (n=18) and kennel G (n=21). Fecal and serum samples from 11 keepers responsible for kennel cleaning and dog control were also collected in five of the seven kennels (two from kennel A, one from kennel B, four from kennel D, two from kennel E and two from kennel G). Overall, enteroparasites were detected by parasitological assays in 66, 36.5% (95% CI: 2.5-43.4%) of the 181 dogs tested. Only one (0.6%) dog was copropositive for S. stercoralis. Among the keepers only one fecal sample, 9.1% (95% CI: 8.6-9.4%) was positive for hookworm by the Lutz method. Serological assays showed that 44 (24.3%) of the 181 dogs were seropositive for S. stercoralis in at least one of the tests in the following kennels: 21 (11.6%) in kennel A; 1 (0.6%) in kennel B; 5 (2.7%) in kennel C; 6 (3.3%) in kennel D; 1 (0.6%) in kennel E; 9 (4.9%) in kennel F and 1 (0.6%) in kennel G. Among the keepers no S. stercoralis seropositive samples were identified using IFAT but 2 (18.2%) of the keepers from kennel D and 1 (9.1%) from kennel G were seropositive by ELISA. The present study demonstrated that the occurrence of S. stercoralis infection in kennel dogs and keepers is low in the city of Uberlândia and that serological assays can contribute to the diagnosis of canine as well as human strongyloidiasis.

Genotoxicity of vesicular fluid and saline extract of Taenia solium metacestodes in somatic cells of Drosophila melanogaster

Neurocysticercosis, the most common parasitic disease of the central nervous system, is caused by cysticerci of the helminth Taenia solium, which is prevalent in developing countries and is reemerging in affluent societies. This helminth is associated with brain tumors and hematological malignancies in humans. In the present study, we analyzed the genotoxicity of vesicular fluid (VF) and a saline extract (SE) of T. solium metacestodes in the Drosophila melanogaster wing somatic mutation and recombination test (SMART). Third-instar larvae derived from standard and high bioactivation crosses were treated for approximately 48 hr with 12.5, 25.0, and 50.0 microg/ml of VF and SE of T. solium metacestodes. Negative (phosphate buffered saline) and positive (10 mM urethane) controls were also included. The results showed that the two test compounds were genotoxic in both crosses of Drosophila. Nevertheless, further research is needed to determine the genotoxic potential of specific compounds present in VF and SE and their role in the development of cancer.

Parasitological and serological diagnosis of Strongyloides stercoralis in domesticated dogs from southeastern Brazil

Canine strongyloidiasis is a parasitic infection caused by the nematode Strongyloides stercoralis and presents a great zoonotic potential. Its confirmation, using coproparasitological methods, is difficult. The detection of serum specific antibodies, however, may facilitate the diagnosis. The aims of this study were to determine the presence of S. stercoralis through the use of parasitological methods and to detect specific antibodies to the parasite in serum samples from domestic dogs by using the indirect fluorescent antibody test (IFAT) on slides and the enzyme-linked immunosorbent assay (ELISA). A total of 215 dogs of various breeds, from the cities of Uberlândia, Araxá and Campo Belo in the State of Minas Gerais, were examined and distributed according to age into the following groups: (I) 19 males and 20 females of 1-2 months old; (II) 11 males and 20 females of 2-month- to 1-year-old and (III) 41 males and 104 females, from 1 to 7 years old. Coproparasitological results showed that 63/215 (29.3%) of the dogs presented some kind of parasite, with two (0.9%) dogs (one from Araxá and the other from Uberlândia) passing S. stercoralis larvae in the feces. Serological results revealed antibodies to S. stercoralis in 45/215 (20.9%) of the dogs, with seropositivity rates of 0% (0/39) in Group I, 22.6% (7/31) in Group II, and 26.2% (38/145) in Group III. No serological cross-reactivity between S. stercoralis and hookworms or Ascaridae was found. Hookworm infections were seen in 31 dogs, but only one of these dogs (infected with both hookworm and Cystoisospora spp.) was S. stercoralis seropositive by IFAT. The present study demonstrated, for the first time, natural S. stercoralis infections in dogs diagnosed by coproparasitological and serological methods. It was concluded that the detection of specific antibodies to S. stercoralis by IFAT and ELISA may contribute to the diagnosis of canine strongyloidiasis.

Use of the paired samples (cerebrospinal fluid and serum) in immunodiagnostic of active and inactive human neurocysticercosis

Paired samples of cerebrospinal fluid (CSF) and serum of 30 patients--10 with active, 10 with inactive neurocysticercosis (NCC), and 10 control subjects--were evaluated by enzyme-linked immunosorbent assay (ELISA) using two Taenia crassiceps metacestode extracts as antigen in order to detect IgG antibodies. In active NCC, high levels of IgG were detected (p < 0.05). The CSF samples showed 80% (CI 72-88) of reactivity in the saline extract (S) and 90% (CI 84-95) in sodium dodecyl sulphate (SDS) and the serum samples were reactive in 90% (CI 84-95) and 100% (CI 98-100) in the S and SDS antigenic extracts, respectively. The use of the paired samples of CSF and serum in active NCC showed equivalent results suggesting that the serum samples could be used as a screening in those patients whose CSF puncture is counter-indicated.

Detection of Cryptosporidium--specific coproantigen in human immunodeficiency virus/acquired immunodeficiency syndrome patients by using a commercially available immunoenzymatic assay

The aim of this study was to verify the occurrence of Cryptosporidium infection in 52 human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients (group 1) and 38 clinically healthy individuals (group 2) by using enzyme immunoassay (EIA). All fecal samples collected were submitted to the Baermann, Lutz and Ritchie methods, the Safranin/Methylene Blue, and Weber's chromotrope modified Trichrome staining techniques, and EIA. In group 1, parasitological staining techniques and EIA were both positive for Cryptosporidium sp. infection in 3/52 (5.8%) samples and both negative in 45/52 (86.5%) samples, while 4/52 (7.7%) samples were positive in EIA and negative in parasitological staining techniques. Concerning group 2, all samples were negative by EIA and microscopy for Cryptosporidium infection. In conclusion, EIA may be an alternative method for detecting Cryptosporidium-specific coproantigen in HIV/AIDS patients.

Strongyloides ratti antigenic components recognized by IgE antibodies in immunoblotting as an additional tool for improving the immunodiagnosis in human strongyloidiasis

IgE antibody response in human strongyloidiasis was evaluated by enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB) using Strongyloides ratti saline extract as heterologous antigen. A total of 50 serum samples of patients who were shedding S. stercoralis larvae in feces (group I, copropositive), 38 of patients with other intestinal parasites (group II), and 38 of subjects with negative results in three parasitologic assays (group III, copronegative) were analyzed. Levels of IgE anti-Strongyloides expressed in ELISA Index (EI) were significantly higher in patients of group I (1.32) than in group II (0.51) and group III (0.81), with positivity rates of 54%, 0%, and 10.5%, respectively. Fifteen S. ratti antigenic components were recognized in IB-IgE by sera of group I, with frequency ranging from 8% to 46%. In group II, only two antigenic bands (101, 81 kDa) were detected in a frequency of 10% and no reactivity was found in group III. Sera with EI values > 1.5 recognized five from 13 specific antigenic bands (70, 63, 61, 44, 7 kDa). It can be concluded that these five antigenic components recognized by IB-IgE using S. ratti antigen might be employed as an additional tool for improving the immunodiagnosis in human strongyloidiasis.

Strongyloides venezuelensis alkaline extract for the diagnosis of human strongyloidiasis by enzyme-linked immunosorbent assay

The present study was conducted to detected IgG antibodies using Strongyloides venezuelensis alkaline extract for the diagnosis of human strongyloidiasis by the enzyme-linked immunosorbent assay (ELISA). Sera from 90 subjects were analyzed (30 with strongyloidiasis, 30 with other parasites and 30 healthy individuals). Results were expressed in antibody titers, which were considered as positive when titer was >80. Sensibility and specificity of the assay were 100% and 96.7%, respectively. It can be concluded that the heterologous alkaline extract could be employed in ELISA as a diagnostic aid in human strongyloidiasis, due to its advantages as easiness of obtaining, practicability in preparing, and high indexes of sensitivity and specificity.

Heterologous antigen extract in ELISA for the detection of human IgE anti-Strongyloides stercoralis

Strongyloides ratti larval extract was used for the standardization of ELISA to detect genus-specific IgE in human strongyloidiasis. Forty serum samples from monoinfected patients shedding S. stercoralis larvae (Group I), 40 from patients with other intestinal parasites (Group II), and 40 from copronegative healthy subjects (Group III) were analyzed. Genus-specific IgE levels (ELISA Index: EI) were significantly higher in the group I (EI = 1.43) than groups II (EI = 0.70) and III (EI = 0.71), showing positivity rates of 55%, 2.5% and 0%, respectively. Similarly, sera from copropositive patients had significantly higher levels of total IgE (866 IU/mL) as compared to those from group II (302 IU/mL) and III (143 IU/mL). A significant positive correlation was found between levels of Strongyloides specific-IgE and total IgE in sera from patients with strongyloidiasis. In conclusion, S. ratti heterologous extract showed to be a useful tool for detecting genus-specific IgE by ELISA, contributing for a better characterization of the immune response profile in human strongyloidiasis.

Western blotting using Strongyloides ratti antigen for the detection of IgG antibodies as confirmatory test in human strongyloidiasis

The present study was conducted to evaluate the frequency of antigenic components recognized by serum IgG antibodies in Western blotting (WB) using a Strongyloides ratti larval extract for the diagnosis of human strongyloidiasis. In addition, the WB results were compared to the enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence antibody test (IFAT) results. Serum samples of 180 individuals were analyzed (80 with strongyloidiasis, 60 with other intestinal parasitoses, and 40 healthy individuals). S. ratti was obtained from fecal culture of experimentally infected Rattus rattus. For IFAT, S. ratti larvae were used as antigen and S. ratti larval antigenic extracts were employed in WB and ELISA. Eleven S. ratti antigenic components were predominantly recognized by IgG antibodies in sera of patients with strongyloidiasis. There was a positive concordance for the three tests in 87.5% of the cases of strongyloidiasis. The negative concordance in the three tests was 94% and 97.5%, in patients with other intestinal parasitoses and healthy individuals, respectively. In cases of positive ELISA and negative IFAT results, diagnosis could be confirmed by WB. ELISA, IFAT, and WB using S. ratti antigens showed a high rate of sensitivity and specificity. In conclusion, WB using S. ratti larval extract was able to recognize 11 immunodominant antigenic components, showing to be a useful tool to define the diagnosis in cases of equivocal serology.

Intestinal parasites and commensals among individuals from a landless camping in the rural area of Uberlândia, Minas Gerais, Brazil

We evaluated the occurrence of intestinal parasites and commensals among children and adults from a landless camping in the rural area of Uberlândia, State of Minas Gerais, Brazil, from October to November 2001. Stool samples from 78 individuals were examined by both the Baermann-Moraes and Lutz methods. Fifty-one (65.4%; CI 54.8 - 76.0) individuals were found to be infected, 23 (45.1%) children and 28 (54.9%) adults, of whom 34 (66.7%) were mono-infected, 9 (17.6%) bi-infected, and 8 (15.7%) poly-infected. In conclusion, the high prevalence of intestinal parasites and commensals suggests that parasitological exams should be periodically carried out in addition to the sanitation education and health special care in this population.

[Occurrence of intestinal parasites and commensal organisms among schoolchildren living in a 'landless farm workers' settlement in Campo Florido, Minas Gerais, State Brazil]

The aim of this study was to verify the occurrence of intestinal parasites and commensal organisms among children attending a school located in a settlement of 'landless farm workers' in Campo Florido, Minas Gerais, Brazil. Coproparasitological analyses performed on 72 school children revealed 59.7% positivity and 4 types of protozoa and 5 types of helminths were identified. It can be concluded that it is necessary to monitor the health conditions of this population.

Ocorrência de parasitas e comensais intestinais em crianças de escola localizada em assentamento de sem-terras em Campo Florido, Minas Gerais, Brasil

O objetivo deste estudo foi verificar a ocorrência de parasitas e comensais intestinais em crianças de escola localizada em assentamento de sem-terras em Campo Florido, Minas Gerais, Brasil. Exames coproparasitológicos realizados em 72 indivíduos evidenciaram 59,7% de positividade, sendo identificados 4 tipos de protozoários e 5 de helmintos. Concluiu-se que há necessidade de acompanhamento das condições de saúde desta população.