Spatiotemporal variation in risk of Shigella infection in childhood: a global risk mapping and prediction model using individual participant data
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Lancet Glob Health
Abstract
Background Diarrhoeal disease is a leading cause of childhood illness and death globally, and Shigella is a major
aetiological contributor for which a vaccine might soon be available. The primary objective of this study was to model
the spatiotemporal variation in paediatric Shigella infection and map its predicted prevalence across low-income and
middle-income countries (LMICs).
Methods Individual participant data for Shigella positivity in stool samples were sourced from multiple LMIC-based
studies of children aged 59 months or younger. Covariates included household-level and participant-level factors
ascertained by study investigators and environmental and hydrometeorological variables extracted from various data
products at georeferenced child locations. Multivariate models were fitted and prevalence predictions obtained by
syndrome and age stratum.
Findings 20 studies from 23 countries (including locations in Central America and South America, sub-Saharan
Africa, and south and southeast Asia) contributed 66 563 sample results. Age, symptom status, and study design
contributed most to model performance followed by temperature, wind speed, relative humidity, and soil moisture.
Probability of Shigella infection exceeded 20% when both precipitation and soil moisture were above average and had
a 43% peak in uncomplicated diarrhoea cases at 33°C temperatures, above which it decreased. Compared with
unimproved sanitation, improved sanitation decreased the odds of Shigella infection by 19% (odds ratio [OR]=0·81
[95% CI 0·76–0·86]) and open defecation decreased them by 18% (OR=0·82 [0·76–0·88]).
Interpretation The distribution of Shigella is more sensitive to climatological factors, such as temperature, than
previously recognised. Conditions in much of sub-Saharan Africa are particularly propitious for Shigella transmission,
although hotspots also occur in South America and Central America, the Ganges–Brahmaputra Delta, and the island
of New Guinea. These findings can inform prioritisation of populations for future vaccine trials and campaigns.
Description
Research Article
Keywords
Diarrhoeal, childhood illness, death, Shigella