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INTRODUCTION: Serological assays are alternative laboratory tools for the diagnosis of parasitic infections. The aim of this work was to evaluate the performance of the indirect fluorescent antibody test (IFAT) and Western blotting (WB) for the detection of IgG anti-Giardia antibodies in human sera. METHODOLOGY: Sera from individuals infected with Giardia duodenalis, other parasites or non-parasitized were selected for serological assays. Ninety-seven sera were tested by IFAT at 1:20 and 1:40 dilutions and of these, 40 samples were also analyzed by WB. RESULTS: The sensitivity and specificity of the IFAT was 97% and 46.9% at 1:20 sera dilution, and 39.4% and 59.4% at 1:40 sera dilution. The low molecular weight polypeptides fractions of 25 kDa, 27-31 kDa and 45-55 kDa were the most frequently identified by the sera of individuals infected with G. duodenalis, along with low cross-reactivity, presenting an individual sensitivity of 42.8%, 50.0% and 57.1%, and specificity of 83.3%, 83.3% and 91.7%, respectively. The highest overall sensitivity of WB (85.7%) was based on the immunoreactivity of sera with at least one of those proteins. The concordance between the detection of G. duodenalis in feces by microscopy and the WB results was considered substantial (Kappa = 0.61). CONCLUSION: Constant exposure to Giardia infection throughout a lifetime can maintain high levels of specific antibodies in serum, even without active infection. Moreover, proteins found in intestinal amoebas may hinder the serological diagnosis of giardiasis in endemic areas due to cross-reactivity, which can be partially solved using Giardia low molecular weight proteins.

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Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is a neglected tropical disease with life-threatening implications. In this study, we conducted a seroepidemiological survey to determine the prevalence and clinical profiles of CD in 217 individuals from an impoverished rural community in Southern Bahia, Brazil. The overall prevalence of CD in the studied community was 0.92%, detected through latent class analysis (LCA). Two individuals tested positive for anti-T. cruzi IgG, both being male farmers. One case was a 22-year-old man born in Camamu, with no evidence of congenital transmission, suggesting other routes of transmission such as vector-borne transmission due to migratory activities. The other case was a 69-year-old man born in São Felipe, who had lived in an adobe/brick house and had a pacemaker due to cardiac involvement caused by CD. The prevalence in this community was lower than expected, given the socioeconomic conditions and environmental factors that contribute to T. cruzi transmission. This could be attributed to the implementation of preventive measures and vector control programs by the Brazilian Government. However, continuous monitoring and surveillance are essential to sustain control efforts and detect any potential re-emergence of the disease. While the overall prevalence was low, the detection of positive cases underscores the need for continued surveillance and control measures in vulnerable populations, such as rural communities. Active surveillance, early diagnosis, and timely treatment are crucial in preventing disease progression and complications, thereby enhancing the effectiveness of screening and treatment programs.

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Strongyloidiasis control is associated with a Th2 immune response. However, alcohol ingestion plays an important role in modulating the immune system. The aim of this study is to evaluate the occurrence of Strongyloides stercoralis infection in alcoholic patients, the levels of circulating cytokines (IFN-γ, IL-2, IL-4, IL-5, IL-10, IL-15 and IL-17), and its correlation with modulation of parasitic load in alcoholic individuals infected with S. stercoralis. A total of 336 alcoholic patients, treated at the Alcoholic Care and Treatment Center were included in this study. The cytokine levels were measured by a commercial ELISA in 80 sera divided into four groups with 20 individuals each: alcoholics infected (ASs+) and not infected (ASs-) with S. stercoralis and non-alcoholics infected (NASs+) and not infected (NASs-) with the helminth. S. stercoralis frequency in alcoholic patients was 16.1% (54/336). The parasitic load varied from 1 to 546 larvae/g of faeces, median and interquartile range (IQR) of 9 and 1.0-62.5 larvae/g of faeces, while in non-alcoholic individuals the parasitic load was less than 10 larvae/g of faeces. Levels of circulating IL-4 were significantly higher in ASs+ when compared with NASs- group (p < .05). An inverse correlation between serum levels of IFN-γ and parasitic load in alcoholic patients infected with S. stercoralis was observed (r = -601; p < 0.01). These results suggest that modulation of IFN-γ production occurs in alcoholic individuals with high parasitic burden.

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BACKGROUND: Microscopy and enzyme-linked immunosorbent assay (ELISA) are routinely used for Cryptosporidium diagnosis, without differentiating the parasite species. METHODS: Children's feces were analyzed by modified Ziehl-Neelsen (mZN) and ELISA for Cryptosporidium diagnosis and by polymerase chain reaction-restriction fragment length polymorphism for species identification. RESULTS: Cryptosporidium frequency was 2.6%. The sensitivity and specificity of ELISA were 85.7% and 99.7%, respectively, with excellent concordance with mZN (kappa=0.854). Parasite species were characterized as Cryptosporidium hominis (78.3%), Cryptosporidium felis (17.4%), and Cryptosporidium parvum (4.3%). CONCLUSIONS: Coproantigen ELISA is as efficient as mZN for Cryptosporidium diagnosis. Cryptosporidium genotyping suggests anthroponotic and zoonotic transmission to children.

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PURPOSE: S. stercoralis diagnosis is currently performed by parasitological methods, mainly by Baermann-Moraes (BM), although Agar Plate Culture (APC) presents a higher sensitivity. New techniques, such as TF-Test® and Coproplus® have been suggested as more practical alternatives. The aim of this study was to evaluate the sensitivity of TF-Test® and Coproplus®, compared with APC, BM and Spontaneous Sedimentation (SS) methods. METHODS: One-hundred and forty male alcoholic patients, who provided three stools samples collected on alternate days, were included in this study. The most frequently found parasite was S. stercoralis, 20% (28/140), and the most sensitive method was APC, 96.4% (27/28), followed by BM, 89.3% (25/28) and SS, 57.1% (16/28). TF-Test® and Coproplus® presented a sensitivity of 46.4 (13/28) and 39.3% (11/28), respectively. In samples with a parasitic load of 1-10 larvae/g of feces, which occurred in 39.3% (11/28) of the infected patients, both the TF-Test® and Coproplus® methods demonstrated sensitivities of 18.2% (2/11), while APC and BM methods reached a sensitivity of 100% (11/11) (p < 0.05). For other intestinal helminth infections, TF-Test® and Coproplus® sensitivities were 22.2 (4/18) and 11.1% (2/18), respectively, this being lower than the SS, 66.7% (12/18) (p < 0.05). On the other hand, for protozoa infection diagnosis, TF-Test® and Coproplus® presented the highest sensitivities, 62.2 (46/74) and 43.2% (32/74), respectively. CONCLUSION: TF-Test® and Coproplus® methods presented the lowest sensitivities for S. stercoralis and other helminth infection diagnosis; therefore, they can be indicated for use in parasitological diagnosis, only when associated with other more effective methods of helminth identification.

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ABSTRACT Background: Microscopy and enzyme-linked immunosorbent assay (ELISA) are routinely used for Cryptosporidium diagnosis, without differentiating the parasite species. Methods: Children's feces were analyzed by modified Ziehl-Neelsen (mZN) and ELISA for Cryptosporidium diagnosis and by polymerase chain reaction-restriction fragment length polymorphism for species identification. Results: Cryptosporidium frequency was 2.6%. The sensitivity and specificity of ELISA were 85.7% and 99.7%, respectively, with excellent concordance with mZN (kappa=0.854). Parasite species were characterized as Cryptosporidium hominis (78.3%), Cryptosporidium felis (17.4%), and Cryptosporidium parvum (4.3%). Conclusions: Coproantigen ELISA is as efficient as mZN for Cryptosporidium diagnosis. Cryptosporidium genotyping suggests anthroponotic and zoonotic transmission to children.

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Introdução: as parasitoses intestinais constituem-se um importante problema de saúde pública mundial. Estas infecções são mais prevalentes em regiões tropicais impactando na morbimortalidade e aumento nos custos para o sistema de saúde. Objetivo: avaliar a prevalência das enteroparasitoses e sua associação com as condições socioeconômicas, sanitárias, ambientais e hábitos de vida em uma comunidade costeira do Nordeste brasileiro. Metodologia: estudo epidemiológico, descritivo e transversal, realizado de modo não probabilístico entre março a junho de 2017, com 105 moradores da Ilha de Boipeba, localizada no Sul da Bahia. O exame parasitológico de fezes foi realizado pelos métodos de sedimentação espontânea, Baermann-Moraes e FAUST. Um questionário foi aplicado para avaliar o perfil sociodemográfico da população. Resultados: do total de indivíduos avaliados, 52,4% eram do sexo feminino e 57,1% tinham entre 15 a 59 anos. Todos os indivíduos possuíam água encanada, porém não tratada, enquanto 91,4% referiu ingerir vegetais crus e 45,7% não higienizavam as mãos antes as refeições. Sintomas gastrointestinais foram relatados em 82,8% dos indivíduos e infecções enteroparasitárias foram diagnosticadas em 69,6%. Os parasitos mais frequentemente encontrados foram Ancilostomídeo (18,1%) e Entamoeba coli (43,8%). O principal fator de risco potencial para contrair a infecção por ancilostomídeos foi a não existência de poço artesiano na residência (RP=4,35), enquanto para Trichuris trichiura foi não dispor de pia no banheiro (RP=3,82). Conclusão: a comunidade analisada apresentou elevada prevalência de enteroparasitoses. Os hábitos precários de higiene e de acesso à água tratada, associados às condições ambientais e climáticas do local, podem ter contribuído para a elevada transmissão de geohelmintos observada.

Introduction: Intestinal parasitic infections are an important public health problem worldwide. They are more prevalent in tropical regions impacting in morbidity and mortality and costs for the health system. Objective: To evaluate the prevalence of enteroparasitosis and its association with socioeconomic, sanitary and environmental conditions and lifestyle habits in a coastal community in the Northeast Brazil. Methodology: This is an epidemiological, descriptive and cross-sectional study, carried out in a non-probabilistic manner between March and June 2017, with 105 residents of Boipeba Island in the Southern Bahia. The parasitological examination of feces was carried out by the methods of spontaneous sedimentation, Baermann-Moraes and FAUST. A questionnaire was applied to assess the sociodemographic profile of the population. Results: Of the total of individuals evaluated, 52.4% were female and 57.1% were between 15 and 59 years old. All individuals had piped, but untreated water, while 91.4% reported eating raw vegetables and 45.7% did not wash their hands before meals. Gastrointestinal symptoms were observed in 82.8% individuals and 69.6% were diagnosed with enteroparasitic infections. The most frequent parasites were the hookworm (18.1%) and Entamoeba coli (43.8%). The main potential risk factor for hookworm infection was the non-existence of an artesian well in the residence (PR=4.35) and Trichuris trichiura it was not having a sink in the toilet (PR=3.82). Conclusion: The analyzed community has a high prevalence of enteroparasitosis, in addition to environmental and climatic conditions that contribute to the transmission of these infections.

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BACKGROUND: Giardia duodenalis is conventionally diagnosed in fecal samples using parasitological methods. However, sensitivity is poor when only a single sample is analyzed, due to intermittent excretion of cysts in feces. Alternatively, the serum antibodies to G. duodenalis can be used for parasite diagnosis and epidemiological studies to determine previous exposure. We compared the rate of G. duodenalis infection between serum anti-Giardia IgG and IgA antibodies and fecal examination in Brazilian children. METHODS: Fecal and serum samples were tested from 287 children at a clinical laboratory and from 187 children at daycare centers. Fecal samples were processed using conventional parasitological methods and coproantigen detection for Giardia diagnosis. Serum samples were tested using an in-house ELISA for detection of anti-Giardia IgG and IgA. RESULTS: G. duodenalis was found in 8.2% (N=39) of the 474 children analyzed. The sensitivity and specificity of ELISA were 80.0% and 90.0% for IgG and 80.0% and 83.3% for IgA, respectively. The total positivity rate of anti-Giardia IgG and IgA in the sera was 13.9% (N=66) and 23.6% (N=112). The agreement between the positivity of specific antibodies and the detection of G. duodenalis in feces was moderate for ELISA-IgG, kappa index (95% CI)=0.543 (0.422-0.664), and mild for ELISA-IgA, kappa index (95% CI)=0.283 (0.162-0.404). Among the children infected with other enteroparasites, 11.6% (N=10) and 24.4% (N=21) showed reactivity to anti-Giardia IgG and to IgA, respectively. This cross-reactivity was more frequent in samples from children infected with Endolimax nana and Entamoeba coli. CONCLUSIONS: The higher frequency of specific antibody reactivity compared with G. duodenalis diagnosis in feces could reflect continuous exposure of children to G. duodenalis infection, resulting in long-lasting immunological memory and/or cross-reactivity with other intestinal amoebas.

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Individuals infected with Strongyloides stercoralis have been reported to produce different immunoglobulins isotypes, yet few studies have evaluated their use in strongyloidiasis diagnosis. The aim of this work was to evaluate the immunoreactivity of different classes and subclasses of anti-S. stercoralis circulating antibodies in alcoholic patients by ELISA and to perform immunoblotting in samples with discordant results between parasitological and immunological methods. 345 male patients with a clinical diagnosis of alcoholism hospitalized at a reference center for alcoholics in Salvador, Bahia, Brazil, were included in this study. The fecal samples were examined by three different parasitological methods (spontaneous sedimentation, Baermann-Moraes and Agar Plate Culture methods). The ELISA was performed for the detection of IgG, IgG1, IgG4, IgE and IgA1 anti-S. stercoralis. Immunoblotting, for the detection of specific IgA1, was used to elucidate discordant results between parasitological and immunological methods. S. stercoralis infection frequency in alcoholic patients by parasitological methods was 21.4% (74/345). Although IgE-ELISA demonstrated a high sensitivity and specificity in non-alcoholic patients, about 30% (22/74) of alcoholics with larvae in feces were negative. IgG1-ELISA detected the lowest frequency of antibodies in alcoholic patients with larvae in feces, only 57% (42/74). IgG4-ELISA was the best assay for S. stercoralis infection immunodiagnosis. Immunoreactivity in the immunoblotting for IgA1 at 90, 75, 26 and/or 17 kDa bands was observed in 92% (33/36) of alcoholics with larvae excretion and negative ELISA for one or more antibody isotypes. In conclusion, IgG4-ELISA showed the highest sensitivity and specificity, thus demonstrating its superiority for strongyloidiasis immunodiagnosis in alcoholic and non-alcoholic individuals. Both, IgE and IgG1-ELISA presented high sensitivities and specificities for S. stercoralis infection diagnosis in non-alcoholics, however there was low reactivity in alcoholic individuals. This can be associated with an increased susceptibility to severe strongyloidiasis in these patients. IgA1-immunoblotting can be used to confirm S. stercoralis infection when there are discordant results between parasitological methods and ELISA.

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Introdução: fibrose cística (FC) é uma doença genética que culmina em alterações na proteína transmembrana CFTR, resultando na produção de muco mais espesso em diversos órgãos, destacando-se os tratos respiratório e digestório. A insuficiência pancreática (IP) acomete até 95% dos pacientes com FC. Objetivos: determinar a frequência de IP através da dosagem de elastase fecal-1 (EF-1) e compará-la com o genótipo de pacientes com FC assistidos em um centro de referência. Metodologia: foi realizado um estudo transversal, incluindo-se pacientes com FC de 0 a 20 anos. Após a inclusão dos sujeitos à pesquisa, foi realizada consulta ao prontuário para a obtenção de dados clinicos e demograficos e amostras de fezes foram obtidas para dosagem da (EF-1). Os pacientes foram submetidos à análise molecular das mutações por métodos convencionais, através da extração do DNA em sangue periférico. Quando duas mutações patológicas não foram identificadas, o sequenciamento de nova geração com utilização da plataforma Illumina HiSeq foi realizado em amostras da mucosa oral. Resultados: foram incluídos 31 pacientes, 17 (54,8%) do sexo feminino, mediana de idade de 10 anos, e apenas um paciente foi classificado como branco. Vinte e dois (70,9%) pacientes apresentaram dosagem de EF-1 inferior a 200 µg/g, compatível com o diagnóstico de IP. Destes, 21 (95,4%) apresentaram dosagem de EF-1 menor ou igual a 15µg/g, caracteristica de IP grave. Todos os pacientes com IP apresentavam duas mutações de classes I a III. Conclusão: a IP foi identificada em 70% dos pacientes, ocorrendo em todos os pacientes com duas mutações de classe I-III.

Introduction: cystic fibrosis (CF) is a genetic disease that culminates in alterations in the CFTR transmembrane protein, resulting in the production of thicker mucus in various organs, especially the respiratory and digestive tract. Pancreatic insufficiency (PI) affects up to 95% of CF patients. Objectives: To determine the frequency of PI by measuring fecal elastase-1 (FE-1) and comparing it with the genotype of CF patients assisted at a referral Center. Methodology: a cross-sectional study was conducted, including patients with CF from 0 to 20 years. After the inclusion of the subjects to the research, medical records were consulted to obtain clinical and demographic data and stool samples were obtained for the measurement of (FE-1). Patients were submitted to molecular analysis of mutations by conventional methods by DNA extraction in peripheral blood. When two pathological mutations were not identified, next-generation sequencing using the Illumina HiSeq platform was performed on oral mucosa samples. Results: thirty one patients were included, 17 (54.8%) female, median age 10 years, and only one patient was classified as white. Twenty-two (70.9%) patients had an FE-1 dosage of less than 200 µg / g, compatible with the diagnosis of pancreatic insufficiency (PI). Of these, 21 (95,4%) had an EF-1 dosage less than or equal to 15µg / g, characteristic of severe PI. All patients with two mutations class I to III were PI. Conclusion: PI was identified in 70% of patients, occurring in all patients with class I-III mutations.

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