Version 1: The role of nutrition in the pathogenesis of neglected tropical diseases: systematic review and meta-analysis

Background: According to the WHO, neglected tropical diseases (NTDs) affect over 2 billion people worldwide. While the links between nutrition and many diseases have become clear over recent decade, NTDs have lagged behind and the linkage with nutrition is largely unknown. We conducted this systematic review with meta-analysis to determine the current status of research on the role of diet in the pathogenesis of NTDs.

Methodology: PubMed, Embase, Scopus and African Journal online databases were searched using predefined search terms. We included all original articles with a case-control design and at least one NTD. The studies had to compare the nutritional parameters between the infected and uninfected.  Articles that did not report original data were excluded. The quality of the studies was assessed using the Newcastle-Ottawa scale. Pooled estimates were conducted using the random-effects model. The publication bias of studies was determined by funnel plots.  Q and I2 statistics were used to assess the heterogeneity of the studies.

Results: After screening 1294 articles, only 16 qualified for the systematic review and 12 for meta-analysis. These predominately had a focus on soil-transmitted helminthiasis (ascariasis, hookworm diseases, trichuriasis) and schistosomiasis, with a minority concerning leishmaniasis and leprosy. Pooled estimates showed an association between intestinal parasites and stunting in children (OR= 1.38, 95%CI: 1.14-1.66, I2 = 0%). We also identified a moderate association established between blood iron deficiency (OR=4.67, 95%CI: 1.91-11.44) and intestinal parasites.

Conclusions/Significance: Of the 20 NTDs, the links between diet and disease have been explored only for a very few. There is a paucity of data from low and middle-income countries and least developed countries where the NTD burden is high. Therefore, more research into the role of nutrition in NTD infection is recommended.