Overcoming challenges in the diagnosis of Schistosoma mansoni infections using POC tests, recombinant protein and monoclonal antibody technology

Control constraints of Schistosomiasis include the lack of diagnostic methods with high sensitivity. We develop a prospective study in southeast Brazil to standardize new sensitive and rapid diagnostic methods for Schistosoma mansoni infection. Currently, we are investigating 6 endemic areas (>1000 individuals with chronic infection) and 84 travelers infected in a fresh water pool (with acute infection). Sera, urine, feces and saliva samples were used for the standardization/validation of innovative methods, including acute, chronic and post‐treatment patients. Comparisons are performed with eggs in feces by 24 Kato‐Katz slides and 2 analysis of Saline Gardient and clinical symptoms. With our new methods using a selected recombinant protein called CCAr, we were able to detect the disease early as 10 days post‐infection and more than 95% of positive cases from chronic and low endemicity areas were obtained. Plus, POC‐CCA® test was improved with a urine concentration step that turned its sensibility from 6% to 56%. Monoclonal antibody and recombinant protein technologies allowed a superior detection method when comparing it to the conventional methods. In conclusion, data showed 100% of sensitivity of chronic patients and 98% of acute patients. Support or Funding Information Fapemig, CNPq, FIOCRUZ, PDTIS (Brazil). Fulbright, NIH, University of Georgia (USA). 1 Schistosomiasis diagnosis data of the individuals from Estreito de Miralta. Brazil, based on the POC‐CCA results and epg obtained by parasitological methods.POC‐CCA (1–2 cassettes) Kato‐Katz Saline Gradient (1 g of feces) (2 slides) (24 slides, 1 g of feces)49 negative 0 epg 46 42 43 ≤10 epg 3 5 4 11–30 epg 0 0 1 31–60 epg 0 2 1 61–60 epg 0 0 0 33 trace 0 epg 24 17 16 ≥ <10 epg 9 12 15 11–30 epg 0 1 1 31–60 epg 0 2 1 61–80 epg 0 1 0 2 positive 0 epg 0 0 0 <10 epg 2 1 1 11–30 epg 0 0 1 31–60 epg 0 1 0 61–80 epg 0 0 0 Total 84 84 84 84doi: 10.1371/journal.pntd.0004778.t0012 Schistosomiasis positivity based on POC‐CCA, Kato‐Katz and Saline Gradient among 84 individuals, Brazil.Prevalence (%)POC‐CCA Before lyophilization 2 After lyophilization 32 Kato‐Katz 30 Saline Gradient 30doi: 10.1371/journal.pntd.0004778.t0023 Sensitivity and specificity obtained by POC‐CCA evaluated against a combined reference techniques of 24 Kato‐Katz slides and Saline Gradient (1 g of feces) before and after lyophilization.Sensitivity (%), 95% CI Specificity (%), 95% CIBefore lyophilization 6 100 After lyophilization 56 83doi: 10.1371/journal.pntd.0004778.t0034 POC‐CCA performance on schistosomiasis diagnosis before and after lyophilization against parasitological methods.POC‐CCA (1–2 cassettes) POC‐CCA after lyophilisation (1–2 cassettes) Kato‐Katz/Saline GradientNegative 49 32 52 Positive 2 27 32 Trace 33 25 ‐ Total 84 84 84doi. 10.1371/journal.pntd.0004778.t0045 Descriptive changes on the POC‐CCA results before and after lyophilization process and comparison against parasitological results.N DescriptionNegatives to traces 13 10 patients had no eggs in stool, although 1 presented hookworms eggs. The other 3 patients had 3, 8 and 52 epg of feces Negatives to positives 11 4 patients with 1, 2, 3 and 55 epg and 7 individuals with no eggs in stool Traces to positives 15 13 patients showed 1–55 epg while 2 individuals had no eggs in stool, but both presented hookworms eggsdoi: 10.1371/journal.pntd.0004778.t0056 Cross reactivity analysis of duplicate POC‐CCA before and after lyophilization of urine samples detected by the combined reference parasitological diagnosis for individuals negative for schistosome eggs.Results POC‐CCA Before lyophilization After lyophilizationHookworms Individual 1 Negative Negative Individual 2 Negative Negative Individual 3 Trace Trace Individual 4 Trace Trace Individual 5 Trace Trace Individual 6 Negative Trace Individual 7 Trace Positive (1+)Hymenolepis nanaIndividual 1 Negative Negative Individual 2 Trace Trace Individual 3 Trace TraceEnterobius vermicularisIndividual 1 Trace Trace Individual 2 Trace Trace Individual 3 Trace Trace Individual 4 Trace NegativeAscaris lumbricoidesIndividual 1 Trace Tracedoi: 10.1371/journal.pntd.0004778.t006