IL1B and malaria: For the meta-analysis of the difference in mean of IL-1β levels between patients with uncomplicated malaria and healthy controls, the funnel plot was asymmetric (Additional file 5: Fig. S5); Egger’s test demonstrated small-study effects (P = 0.03) and contour-enhanced funnel plot demonstrated the distribution of the MDs in both significant and non-significant areas (Additional file 6: Fig. S6), indicating that the cause of funnel plot asymmetry was due to publication bias and heterogeneity of the MDs in the included studies.