Accuracy and precision of dried urine spot method for the detection of Schistosoma mansoni circulating cathodic antigens in resource-limited settings.

BACKGROUND: The World Health Organization recommends the use of Schisto point-of-care circulating cathodic antigens (Schisto POC-CCA) for screening of Schistosoma mansoni as it offers better sensitivity than microscopy. However, there are limitation facing the use of this method including timely availability of the test cassettes. The aim of this study was to determine the reliability of dried urine spot (DUS) method for collection of urine and detection of S. mansoni using Schisto POC-CCA cassettes in a resource-limited settings. METHODS: A cross-sectional study was conducted between October and November 2022 among 250 primary school children in Sengerema District, northwestern Tanzania. S. mansoni CCA was detected in filter paper-based DUS, liquid urine using DUS Schisto POC-CCA (index), and direct urine Schisto POC-CCA (comparator) methods respectively. S. mansoni eggs in stool were detected using duplicate Kato-Katz (KK) method. The measures of accuracy were computed and compared between the index and comparator methods. The strength of agreement between inter-raters precisions was tested using Cohen's kappa (k). RESULTS: This study revealed S. mansoni prevalence rates of 28.8%, 54.0% and 50.8% by duplicate KK, direct urine Schisto POC-CCA and DUS Schisto POC-CCA methods respectively. The mean intensity of infection among infected participants was 86.3 eggs per gram of stool (EPG) ranging from 12.0 EPG to 824.0 EPG. The sensitivity of DUS Schisto POC-CCA and direct urine Schisto POC-CCA was 94.44% (95% CI: 89.15-99.74%) and 97.22% (95% CI: 93.43-100.00%) respectively. The DUS Schisto POC-CCA method had slightly higher specificity (66.85%) than direct urine Schisto POC-CCA method (63.48%). The accuracy of the DUS Schisto POC-CCA was found to be slightly high (74.80%, 95% CI: 68.94-79.06%) compared to that of direct urine Schisto POC-CCA (73.20%, 95% CI: 67.25-78.59%). There was good agreement between two laboratory technologists who performed the DUS Schisto POC-CCA method on similar samples (k = 0.80, 95% CI: 0.59-0.95). CONCLUSIONS: The DUS Schisto POC-CCA method had comparable S. mansoni detection accuracy to direct urine Schisto POC-CCA. This suggests that the method could be a potential alternative to direct urine Schisto POC-CCA for screening S. mansoni in resource-limited situations.

Dried urine spot method for detection of Schistosoma mansoni circulating cathodic antigen in resource-limited settings: a proof of concept study.

Background: Among the challenges in schistosomiasis surveillance and mapping surveys is the lack of a sensitive diagnostic method especially in low transmission setting. Currently, the WHO recommends the use point-of-care circulating cathodic antigen (Schisto POC-CCA) tests for surveillance and mapping of intestinal schistosomiasis. However, Schisto POC-CCA test has its drawbacks, one of which is the timely availability of test kits. One approach to overcoming this challenge is to develop a low-cost sampling method that allows for the collection and transport of urine specimens even in resource-limited settings. Objective: To develop a simple and efficient method for the collection and detection of Schistosoma mansoni (S. mansoni) CCA using urine spotted onto filter paper. Methodology: To develop a dried urine spot (DUS) method, various dried matrix extraction parameters were tested and optimized using predesigned steps. The parameters include the size of filter paper (determined by the number of punches), volume of solvents, and type of solvent. Moreover, we optimized the incubation conditions (time and temperature). Urine and stool specimens to conduct the experiments were collected from volunteer fishermen in Mwanza and this project staff. Data were entered into the Microsoft Excel spreadsheet and IBM Statistical Package for the Social Sciences, version 20 for analysis. Results: The optimal results were obtained when the procedure was run under the following conditions: Five punches of filter paper containing DUS were dissolved in 150 µl of distilled water and incubated at room temperature for 24 hours in an Eppendorf tube. More than 93% of the assays performed under these conditions produced results that were either comparable to or significantly better than the standard method. Conclusion: This study demonstrates the feasibility of collecting urine specimen (DUS) using filter paper and detecting Schistosoma CCA from DUS specimen using the Schisto POC-CCA cassette test.

Trends in diarrhea hospitalizations among infants at three hospitals in Tanzania before and after rotavirus vaccine introduction.

BACKGROUND: The Tanzania Ministry of Health introduced monovalent human rotavirus vaccine in January 2013, to be administered at ages 6 and 10 weeks. Data suggest there was high vaccine uptake. We used hospital ward registers from 3 hospitals to examine trends in diarrhea hospitalizations among infants before and after vaccine introduction. METHODS: Ward registers from Dodoma Regional Referral Hospital (Central Tanzania), and two hospitals in Mbeya (Southwest area), Mbeya Zonal Referral Hospital and Mbalizi Hospital, were used to tally admissions for diarrhea among children by age group, month and year. Rotavirus surveillance had started at these hospitals in early 2013; the proportion of infants enrolled and rotavirus-EIA positive were examined by month to determine peak periods of rotavirus disease post-vaccine introduction. RESULTS: Registers were available for 2-4 prevaccine years and 2-3 post introduction years. At Dodoma Regional Referral Hospital, compared with the mean of 2011 and 2012, diarrhea hospitalizations among infants were 26% lower in 2015 and 58% lower in 2016. The diarrhea peak shifted later in the year first by 1 and then by 2-3 months from prevaccine. At the Mbeya hospitals, the number of diarrhea admissions in prevaccine period varied substantially by year. At Mbeya Referral Hospital, diarrhea hospitalizations among infants were lower by 25-37% in 2014 and 11-26% in 2015, while at Mbalizi Hospital, these hospitalizations were 4% lower in 2014 and 14% higher in 2015. Rotavirus testing data demonstrated a lowering of the prevaccine peak, a shift in timing of the peak months and indicated that other diarrheal peaks in post-introduction years were not due to rotavirus. CONCLUSIONS: In this ecological evaluation, total diarrhea hospitalizations among infants were lower (≥25% lower in ≥1 year) following introduction in 2 of 3 hospitals. There are challenges in using ward registers to ascertain possible impact of rotavirus vaccine introduction on trends in hospitalizations for treatment of all diarrheal illness.

Detection of rotavirus before and after monovalent rotavirus vaccine introduction and vaccine effectiveness among children in mainland Tanzania.

BACKGROUND: Monovalent rotavirus vaccine (RV1) was introduced in Tanzania in January 2013 under the Reach Every Child initiative, to be given at ages 6 and 10 weeks. We used the sentinel hospital rotavirus surveillance system to examine the rotavirus detection rate before and after vaccine introduction and estimate vaccine effectiveness. METHODS: Before vaccine introduction, rotavirus surveillance was established at two mainland hospitals; children admitted for acute diarrhea were eligible for enrollment and stools were tested for rotavirus antigen. We compared the rotavirus positivity rate in the pre-vaccine period (Tanga Hospital, 2009 and 2011; Bugando Medical Centre, 2012) to that from post-introduction years, 2014-2015. In 2013, surveillance was established at 9 additional hospitals. We examined rotavirus positivity among infants at these sites for 2014-2015. We obtained vaccine records and calculated vaccine effectiveness at 3 sites using case-test-negative control design. RESULTS: At Tanga Hospital, the rotavirus positivity rate among infants was 41% (102/251) pre-vaccine and 14% (28/197) in post-vaccine years (rate ratio: 0.35 [95% CI 0.22-0.54]). At Bugando, the positivity rate was 58% (83/143) pre-vaccine, and 18% (49/277) post-introduction (rate ratio 0.30 [95% CI 0.210.44]). Results were similar among children <5 years. At the new sites, the median site rotavirus positivity rate among infants was 26% in 2014 (range 19-44%) and 18% in 2015 (range 16-33%). The effectiveness of ≥1 RV1 dose against rotavirus hospitalization among children 5-23 months was 53% (95% CI: -14, 81), and 66% (95% CI: 9-87) against hospitalization with intravenous rehydration. Following introduction, peak rotavirus activity occurred later in the year and appeared more concentrated in time. CONCLUSION: Rotavirus surveillance data from Tanzania indicate that the rotavirus positivity rate among children hospitalized with diarrhea that were enrolled was substantially reduced after vaccine introduction. Low positivity rates among infants were detected at hospitals across the country. Overall, the data support that rotavirus vaccine has been successfully introduced and is effective in Tanzanian children.