Case-Control Study of Household and Environmental Transmission of Typhoid Fever in India

Abstract

Background Typhoid fever causes substantial morbidity and mortality in low- and middle-income countries. We conducted a case-control study in Vellore, southern India, to understand risk factors for transmission of typhoid. Methods From April 2018 to October 2019, households of blood culture-confirmed typhoid cases that occurred within a fever surveillance cohort aged 6 months–15 years, and controls matched for age, sex, geographic location, and socioeconomic status, were recruited. Information on risk factors was obtained using standard questionnaires. Household and environmental samples were collected for detection of Salmonella Typhi using real-time polymerase chain reaction. Multivariable analysis was used to evaluate associations between risk factors and typhoid. Results One hundred pairs of cases and controls were recruited. On multivariable regression analysis, mothers eating food from street vendors during the previous week (odds ratio [OR] = 2.04; 95% confidence interval [CI], 1.03–4.12; P = .04) was independently associated with typhoid, whereas treatment of household drinking water (OR = 0.45; 95% CI, 0.25–0.80; P = .007) was protective. There was no significant difference in S Typhi detection between the environmental samples from case and control households. Conclusions Street-vended food is a risk factor for typhoid in densely populated urban communities of Vellore. Improved sanitation facilities and awareness about point-of-use water treatment are likely to contribute to typhoid control.

Wastewater surveillance forSalmonellaTyphi and its association with seroincidence of enteric fever in Vellore, India

“…The positivity of Moore swabs (15.30%) was two-fold higher than that of grab samples (7.50%). This finding aligns with the findings of a previous study [32], where grab sampling using the BMFS method showed 3.42% positivity, and Moore swabs showed 8.67%. Grab samples reflect the S. Typhi status in WW at collection time, while Moore swabs capture particulates and organisms during deployment.…”

“…This study aimed to demonstrate the effectiveness of ES of WW as an alternative to blood culture-based surveillance for quantifying typhoid burden in resource-limited settings. In an earlier case-control study, environmental samples from households of participants diagnosed with typhoid were processed using both grab sampling and Moore swabs [32]. The odds ratio (OR) of WW positivity from typhoid-positive households was 1.34 for Moore swabs and 4.17 for grab sampling using the Bag-mediated filtration system (BMFS).…”

Determinants of Typhoid Fever Occurrence in Regions with High Risk of Contracting Communicable Diseases: Systematic Review and Meta-analysis

“…Studies published or published research between 2018 and 2019 and in 2021 in India, targeting children and younger under 16 years, also reported an association of TF with contaminated food [53]. Importantly, the treatment of drinking water, such as via filtration, reverse osmose, or boiling, can decrease TF occurrence.…”