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Combination of Adhesive-tape-based Sampling and Fluorescence in situ Hybridization for Rapid Detection of Salmonella on Fresh Produce
Published on: October 18, 2010
Environmental surveillance for Salmonella Typhi to detect the typhoid burden in Yogyakarta, Indonesia
Vicka Oktaria1, Indah Kartika Murni2, Amanda Handley3
1Department of Biostatistics, Epidemiology, and Population Health, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia; Center for Child Health - Pediatric Research Office, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia.
Background:
In low and middle-income countries (LMICs), understanding the burden of typhoid disease has been challenging as clinical surveillance based on blood culture data alone often poorly represents the community burden. Underreported cases, unclear case definitions, the presence of a chronic carrier state and emerging antimicrobial resistance necessitate alternative approaches to assess disease prevalence and target public health interventions, such as vaccine introduction. This study aimed to assess the feasibility of wastewater and environmental surveillance (WES) in measuring the prevalence of typhoid infection in Indonesia.
Methods:
Between October 11, 2022, and August 31, 2023, WES was conducted in 18 locations across 3 districts in Yogyakarta province, Indonesia. Samples were collected fortnightly from wastewater treatment plants (WWTPs), manholes, a river, and public spaces, using grab and passive sampling methods. Salmonella Typhi (S. Typhi) detection was conducted using quantitative PCR for S. Typhi genes (ttr, tviB, and staG - all positive).
Results:
Of the 406 samples collected, 13 % (51/406) tested positive for S. Typhi, with monthly positivity rates ranging from 2 % (1/51) in March 2023 to 47 % (16/34) in October 2022. Mean concentrations (in log10) in ttr, tviB, and staG in grab samples were 0.67 (SD ± 0.99), 0.23 (SD ± 1.14), and -0.11 (SD ± 1.05). The highest detection rates were observed in samples from the river compared to central WWTPs (OR 12.68; 95 % CI 2.03-79.20, P = 0.007). No correlation was observed between rainfall and S. Typhi gene detection (P > 0.05 for all genes).
Conclusion:
WES is feasible in Indonesia and can be used to monitor typhoid disease burden in an endemic region. High positivity rates from the river and septic tanks in traditional markets support a broad approach to sampling in LMICs where formal wastewater management systems may not accurately represent community disease prevalence due to its low population coverage. WES can be a valuable tool to inform public health responses, including vaccine introduction.
