Comparative study of the accuracy of different technique for the laboratory diagnosis of schistosomiasis mansoni in areas of low endemicity in Barra Mansa City, Rio de Janeiro State, Brazil

Schistosomiasis constitutes a major public health problem, with an estimated 200 million people infected worldwide. Many areas of Brazil show low endemicity of schistosomiasis, and the current standard parasitological techniques are not sufficiently sensitive to detect the low-level helminth infections common in areas of low endemicity (ALEs). This study compared the Kato-Katz (KK); Hoffman, Pons, and Janer (HH); enzyme-linked immunosorbent assay- (ELISA-) IgG and ELISA-IgM; indirect immunofluorescence technique (IFT-IgM); and qPCR techniques for schistosomiasis detection in serum and fecal samples, using the circumoval precipitin test (COPT) as reference. An epidemiological survey was conducted in a randomized sample of residents from five neighborhoods of Barra Mansa, RJ, with 610 fecal and 612 serum samples. ELISA-IgM (21.4%) showed the highest positivity and HH and KK techniques were the least sensitive (0.8%). All techniques except qPCR-serum showed high accuracy (82­95.5%), differed significantly from COPT in positivity , and showed poor agreement with COPT. Medium agreement was seen with ELISA-IgG (Kappa = 0.377) and IFA (Kappa = 0.347). Parasitological techniques showed much lower positivity rates than those by other techniques. We suggest the possibility of using a combination of laboratory tools for the diagnosis of schistosomiasis in ALEs.

Evaluation of the sensitivity of IgG and IgM ELISA in detecting Schistosoma mansoni infections in a low endemicity setting.

Schistosomiasis is a major public health concern, with 200 million people infected worldwide. In Brazil, this disease has been reported in 19 states, and its prevalence in the city of Barra Mansa in Rio de Janeiro State is 1 %. The parasitological diagnostic methods currently available in these areas lack sensitivity; however, enzyme-linked immunosorbent assays (ELISAs) have been employed successfully for the diagnosis of schistosomiasis by using antibodies against antigens of Schistosoma mansoni adult worms and eggs, and for the detection of circulating antigens. The objective of this study was to determine systematically the prevalence of S. mansoni infection in the peripheral areas of Barra Mansa. A cross-sectional study was conducted from April to December 2011 by using probabilistic sampling that collected 610 fecal samples and 612 serum samples. ELISA-IgG with total extracts and ELISA-IgM with trichloroacetic acid-soluble fractions were employed to detect antibodies against S. mansoni and were compared with the Kato-Katz and Hoffman parasitological techniques. Among the individuals studied, anti-S. mansoni antibodies were detected in 11.16 % (n = 71) by ELISA-IgG and in 20.75 % (n = 132) by ELISA-IgM, while the parasitological techniques showed 0.82 % (n = 5) positivity. The agreement between the two ELISA tests was 85.38 % (n = 543), and 8.65 % (n = 55) of the serum samples showed positive results in both tests. The higher positivity of the ELISA-IgM test corroborates the results of previous reports and indicates that the test may be a useful tool in epidemiological studies, particularly in areas of low endemicity for S. mansoni.

The first case of Angiostrongylus cantonesis eosinophilic meningitis diagnosed in the city of São Paulo, Brazil

Introduction: Angiostrongylus cantonensis is a natural parasite found in lung arteries of rats, which in humans may cause eosinophilic meningitis. Objective: To report the first case of eosinophilic meningitis caused by Angiostrongylus cantonensis in the city of São Paulo, Brazil. Case report: A male patient, 11 years old, living in the southern area of São Paulo, was admitted to the Pediatric Emergency Department with ongoing headaches for three days, but no fever or any other complaint. The presence of snails and rodents was reported in the peridomicile. The child was awake, lucid, oriented; muscular strength preserved, isochoric, photo reagent pupils and terminal nuchal rigidity - Glasgow Coma Scale (GCS) = 15. The laboratory tests showed a mild leukocytosis with 1736 eosinophils/mm3 and the CSF analysis disclosed 160 leukocytes/mm3 with 36% of eosinophils. The bacterial culture was negative. Computed Cerebral Tomography showed no alterations. The RT-PCR assay for detecting Angiostrongylus cantonensis larvae and DNA was negative. ELISA antibodies for IgG anti-A. cantonensis was negative in serum and undetermined in CSF and samples collected five days after the onset of symptoms. Seroconversion was observed in the sample collected 135 days later. Conclusion: the epidemiological and clinical data, the CSF alterations with eosinophilia and the seroconversion strongly suggest Angiostrongylus cantonensis eosinophilic meningitis.

Introdução: Angiostrongylus cantonensis é um parasito natural das artérias de pulmões de ratos, que pode causar, em humanos, meningite eosinofílica. Objetivo: Relatar o primeiro caso de meningite eosinofílica causado por A. cantonensis na cidade de São Paulo, Brasil. Relato de caso: Paciente do sexo masculino, 11 anos, residente na zona sul de São Paulo, foi admitido no serviço de emergência pediátrica com história de cefaléia há três dias, sem febre ou outras queixas. Relato de presença de moluscos e roedores no peridomicílio. Ao exame físico, criança desperta acianótica, anictérica, hidratada; lúcido, orientado; força muscular preservada, isocórica, pupilas fotorreagentes e rigidez de nuca terminal - Glasgow Coma Scale = 15. Exames laboratoriais indicaram leve leucocitose com 1736 eosinófilos/mm3 e a análise do líquor revelou a presença de 160 leucócitos/mm3 com 36% de eosinófilos. Cultura para bactérias negativa. Tomografia cerebral sem alterações. Pesquisa direta de larvas e de DNA por PCR-RT para Angiostrongylus cantonensis foi negativa. ELISA para anticorpos IgG anti-A. cantonensis negativo no soro e indeterminado no líquor nas amostras coletadas após cinco dias do início dos sintomas. Soroconversão observada na amostra coletada após 135 dias. Conclusão: A história epidemiológica, dados clínicos, alterações liquóricas com presença de eosinofilia e a soroconversão sugerem fortemente o diagnóstico de meningite eosinofílica por A. cantonensis.