A scoping review on the associations and potential pathways between malnutrition and measles

Amid a measles resurgence worldwide, many affected regions also find themselves in circumstances of conflict, humanitarian or political crises, climate extremes, ongoing pandemic challenges, income inequality and economic downturns. Those contextual factors have driven increases in worldwide undernourishment over the past year. The overlap and frequent occurrence of those socio-structural determinants in fragile geographies is worrying as a synergistic relationship between measles and malnutrition has been reported. A scoping review was conducted to map current evidence and identify research gaps on the association between malnutrition and measles. Sixty-seven studies were retained following a search of multiple databases, snowballing and consultations with experts. Studies reported on a measure of association, a relationship, or potential mechanisms behind the link between malnutrition and measles. Overall, there was evidence of a positive correlation between undernutrition and reported measles incidence and mortality. All studies reviewed found an association between vitamin A deficiency and increased likelihood of incident measles, measles-related complications and measles-related deaths. Available evidence also suggested that therapeutic vitamin A can significantly reduce the odds of measles-related mortality, and preventative vitamin A can reduce reported measles incidence. Little data shed light on potential pathways behind malnutrition and measles. Inconsistent variable definitions (i.e. malnutrition and measles cases) across studies precluded calculating a cumulative effect size, and findings may be impacted by uncontrolled confounding factors. This scoping review reinforces the hypothesis of a synergistic relationship between measles and malnutrition and highlights the need for an integrated approach to the delivery of malnutrition interventions and measles prevention and control. In addition, further robust studies are needed to better define pathophysiological targets for interventions and allow for stronger inferences to policy making. Future research should also consider using a standardized approach to defining malnutrition and measles to ensure comparability of outcomes across studies.