Prevalence of Sarcoptes scabiei infestation and its associated factors among primary school children: A school-based cross-sectional survey in the Rufiji district, Tanzania.

Objectives: This study aimed to investigate the prevalence of Sarcoptes scabiei infestation and its associated factors among primary school children (PSC) in the Rufiji district. Methods: A quantitative school-based cross-sectional study was conducted among 447 PSC in the Rufiji district. The prevalence of scabies among PSC was determined by clinical examination and by microscopic examination of skin samples for the presence of S. scabiei. A structured questionnaire was used to gather data on factors associated with S. scabiei infestation. Descriptive analysis, Fisher's exact, chi-square tests, and logistic regression analysis were used to analyze the data. Results: The prevalence of scabies was 2.0%. Of the assessed factors, only physical contact with a person having itchy skin lesions (Adjusted Odds Ratio [AOR]=4.04, 95%CI 4.39-12.50) and infrequency of changing clothes before laundry (AOR=2.99, 95%CI 1.35-4.94) were significantly associated with scabies. The majority of participants demonstrated low levels of knowledge, with half exhibiting poor attitudes and inappropriate healthcare-seeking behaviors. Conclusions: There was an ongoing transmission of scabies among PSC in the Rufiji district, with the factors associated with the transmission being physical contact with a person who had an itchy skin lesion and the infrequency of changing clothes before laundry. Therefore, there is a need for regular clinical screening and treatment of positive cases with preventive measures on contact and provision of health education.

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.

Subclinical vascular damage in Schistosoma spp. endemic regions.

Background: Cardiovascular abnormalities have been described in patients with schistosomiasis. Their true prevalence and clinical features in endemic settings are unknown. Patients and methods: The study aimed to assess the prevalence of subclinical cardiovascular damage in a population endemic to schistosomiasis. A cross-sectional study was conducted using colour-ultrasound assessment of abdominal and carotid arteries among adults aged >18 years living in Kome Island, Tanzania. Carotid intimal medial thickness, carotid plaque, mean abdominal aortic diameter, and presence of aneurysms were assessed. Anamnestic data on previous Schistosoma infection was collected; the actual prevalence of Schistosoma mansoni and Schistosoma haematobium was also assessed through stool and urine investigations. Results: A total of 264 participants (166 female, 98 male) were enrolled (mean age of 50±15.5 years). The history of previous schistosomiasis was 27.3%, and actual positivity for Schistosoma mansoni was 5.9%. The Latero-lateral Abdominal Aortic Diameter was significantly increased among participants with a previous history of schistosomiasis (16.7±2.8 mm vs. 17.6±3 mm; p=0.02), with an aOR of 1.15 [CI 1.04-1.28]; p=0.007]. Conclusions: The significant difference in the Latero-lateral Abdominal Aortic Diameter in participants with previous Schistosomiasis history schistosomiasis, suggests the need for further investigations on aortic damage in endemic populations, independently from the positive laboratory investigations.