Similarly, among studies utilizing microscopy alone as the method for diagnosing the presence of malaria parasites, a significant decrease in CAT levels was observed in malaria cases compared with those in uninfected controls (P = 0.04, Hedges’ g: − 0.91, 95% CI: − 1.76–(− 0.06), I2: 98.62, 13 studies, Table 3). Here, CAT is linked to malaria.