The effects of exposures to mycotoxins on immunity in children: A systematic review

The majority of childhood deaths occur in low-income countries, with vaccine-preventable infections contributing greatly. Of the many possible environmental factors that could hamper a child's immune response, mycotoxins rank among the least studied in spite of the high exposure in vulnerable populations. Aflatoxin crosses the placenta, is secreted in breast milk and is consumed widely in weaning diets by children with developing organ systems. This review describes the effects of mycotoxin exposure on immunity in children that may contribute to sub-optimal vaccine effectiveness. We searched electronic databases and references of identified articles for relevant studies on the effects of mycotoxins on the immune system in children. Geographical location, publication year, study design, sample selection, sample size, mean age, route of exposure were extracted on a standard template. Quality was assessed using Joanna Briggs Institute tool for appraisal of systematic reviews for prevalence studies. Our analyses and reporting were conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Out of 806 articles screened, 5 observational studies met criteria for inclusion for review. The definition of exposures to mycotoxins and outcomes varied across the studies. Exposure to mycotoxins was positively associated with low birth weight and concentration of antibodies to asexual malaria parasites and hepatitis B surface antigen, and negatively associated with death and sIgA, antibodies to pneumococcal antigen 23. Despite the far-reaching clinical and public health effects of mycotoxin exposure among children, studies on the effects of mycotoxin exposure on immunity in children were few, small and mostly of low quality. There is an urgent need for carefully designed prospective studies in this neglected field to inform policy interventions for child health in settings where exposure to mycotoxins is high.