Incidence of diarrhoeal disease among children aged less than five years in low- and middle-income countries: a systematic review.

Background: Diarrhoea was the second leading cause of death among children aged <5 years in 2019. Most of these deaths occurred in low- and middle-income countries (LMICs). Summarising the available up-to-date evidence on the incidence of diarrhoeal disease among children could help track the effectiveness of diarrhoea prevention and control efforts. We summarised available evidence on the incidence of diarrhoea among children aged <5 years in LMICs. Methods: We included cross-sectional or cohort studies that reported diarrhoeal incidence among children aged <5 years in LMICs that were published between 2010-22 in English. Two authors searched, reviewed the quality of the selected articles, and extracted the data. We searched Medline/Pubmed, Web of Science, Scopus, CINHAL, EMBASE, WorldCat, OpenGrey, dissertations/theses, reports, and Google Scholar. We screened articles by title, abstract, and full text. Results: We included 15 articles that met the inclusion criteria in the analysis. Four studies were from Africa, seven were from Asia, two were from Brazil, and two were from Nicaragua. Seven studies were conducted in urban settings, six in rural settings, and two in urban and rural areas. The highest incidence of diarrhoea was 5200 episodes of diarrhoea per 1000 child-years, and the lowest was 60.4 episodes of diarrhoea per 1000 child-years. Conclusions: There is limited evidence on the incidence of diarrhoea among children aged <5 years in LMICs. The available studies identified major differences in the incidence of diarrhoea by country, 60.4 in China, and 5200 episodes of diarrhoea per 1000 infants. We recommend more up-to-date primary studies on the incidence of diarrhoea among children aged <5 years in LMICs to monitor and evaluate the effectiveness of diarrhoea control and prevention policies and interventions. Registration: PROSPERO: CRD42022290180.