Non-inferiority of point of care ultrasound and rapid diagnostic tests in detection of sub-clinical and asymptomatic typhoid carriage in rural Bangladesh
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Citation
Abstract
BACKGROUND: Asymptomatic, chronic carriage of typhoid fever is a major contributor to persistence of typhoid in vulnerable populations in lower- and middle-income countries despite improved water and sanitation, and vaccination efforts. Little is known, however, about the number and geographic distribution of chronic and asymptomatic carriers of typhoid. Since these persons are shedding bacterial asymptomatically, they are difficult to detect because they typically do not come into contact with health services, which is essential for typhoid epidemic surveillance. The current gold standard for detection of chronic typhoid carriage is blood culture analysis, a technique dependent on laboratory facilities, highly trained staff, and often proximity to urban centers. In order to promote more active surveillance, particularly in more rural areas, and better assess numbers of chronic carriers at static funding levels, a new approach is necessary.
OBJECTIVE: To evaluate a novel method of typhoid surveillance in chronic and asymptomatic carriers against the gold standard in a rural population in Bangladesh.
METHODS: This will be a cross-sectional study where a combination of handheld point of care (POC) ultrasound for gallstone detection and rapid diagnostic tests for typhoid will be compared against the gold standard blood culture analysis. Rural residents of Mirzapur will be recruited at local clinics when reporting with fever and culture-confirmed typhoid. Household contacts of recruited individuals will be subsequently screened through POC ultrasounds and RDT. Positive cases detected through the experimental approach will be compared against blood culture analysis. A non-inferiority analysis will be conducted to compare the two methodologies.
EXPECTATIONE: By introducing a novel and more accessible method of typhoid detection, this study will lead to more precise prevalence estimates of chronic carriers and will address the need for a more scalable surveillance mechanism for typhoid fever thereby offering a broader detection of asymptomatic and chronic carriers.
RELEVANCE: This work has the potential of lowering rates of endemic transmission in a rural population and enhancing prevention and response efforts in regions with limited resources who suffer the greatest burden of this infectious disease.