Detection of schistosomiasis in an area directly affected by the São Francisco River large-scale water transposition project in the Northeast of Brazil

Abstract

Introduction: The development of the São Francisco River Integration Project [Projeto de Integração do Rio São Francisco (PISF)] in the State of Ceará, Brazil, has resulted in environmental and socioeconomic changes with potential risks to public health. We aimed to determine the presence of Schistosoma mansoni infections in schoolchildren (aged 7-14 years) and workers from the construction site in an area under the direct influence of the PISF in the municipality of Brejo Santo-CE, to aid in the prevention and control of schistosomiasis. Methods: We conducted a cross-sectional study using two S. mansoni-detection methods: detection of S. mansoni eggs by the Kato-Katz parasitological method in stool samples (assessed in triplicate for each sample) and S. mansoni circulating cathodic antigen by the point-of-care immunochromatographic rapid test (POC-CCA) in urine. Results: In general, the positivity rates for S. mansoni detection were 1.9% (2/106) among schoolchildren and 2.9% (4/138) among workers. No child had evidence of S. mansoni eggs in their stools; 1.9% tested positive by the POC-CCA method. Among workers, two (1.4%) tested positive by the Kato-Katz test and three (2.2%) by the POC-CCA test. If the POC-CCA test results that were scored as traces were considered negative, then the positivity rates dropped to 0.9% and 0.7% for schoolchildren and workers, respectively. Conclusions: The active transmission of schistosomiasis in a region covered by the PISF was recognized, reinforcing the necessity to consolidate surveillance and control actions, as well as structural sanitation measures to reverse the social determinants of the disease.

Identification of Biomphalaria sp. and other freshwater snails in the large-scale water transposition project in the Northeast of Brazil

“…There is also the risk of snail dispersal to all municipalities through which these waters will circulate, reaching the Metropolitan Area of Fortaleza whose suburbs have favorable conditions for the disease transmission outbreaks. Moreover, migratory movements, generated by these changes, can contribute to the establishment of the transmission cycle, which was demonstrated by our research group in this region, where PISF workers already infected with S. mansoni were identified 29 .…”

Diagnosis of Schistosoma mansoni infections: what are the choices in Brazilian low-endemic areas?

“…Compared to the results given by K-K (two slides), Bezerra et al 49 demonstrated that agreement between POC-CCA® negative trace is higher than POC-CCA® positive trace (Kappa = 0.12 vs 0.03). Silva et al 50 presented divergent data from previous findings. Compared to the reference method, Lindholz et al 36 showed a higher agreement index when trace results were considered negative (Kappa = 0.15 vs 0.28), while Oliveira et al 33 demonstrated the opposite.…”

“…There are 10 published studies that were conducted in Brazil. 25 , 26 , 33 , 36 , 39 , 47 , 48 , 49 , 50 , 51 The decision to adopt POC-CCA® for use in low-endemic areas of Brazil remains questionable for a number of reasons. Specifically, inadequate estimation of sensitivity and specificity of the POC-CCA® exists because of the absence of a highly sensitive reference method to evaluate its performance, interpretation of trace as either a positive or a negative reading can occur, and this test possesses low sensitivity for the detection of low-intensity infections.…”

“… 46 Only 10 studies were conducted in Brazil, which has a significantly different prevalence and morbidity profile, and these tests yielded controversial results regarding sensitivity and specificity. 25 , 26 , 33 , 36 , 39 , 47 , 48 , 49 , 50 , 51 …”

Tools for Detection of Schistosomiasis in Resource Limited Settings

“…CCA test has been suggested to be more sensitive than KK test, even when compared with three KK thick smears; in primary-school children that were treated with PZQ, one POC-CCA was found to be more sensitive than six KK in monitoring and evaluating the efficacy of PZQ in parasite clearance. POC-CCA has the advantage of using urine samples instead of stool for analysis, thereby increasing the acceptability by patients and the applicability for epidemiological surveys in large populations [ 37 ]. When being used in combination with serology for S. mansoni , a 100% detection sensitivity was achieved when compared to 95.7% and 91.3% sensitivity by serology and POC-CCA, respectively [ 38 ].…”