Anti-saliva IgG serum levels according to malaria occurrence. Serums were collected from non-infected individuals (n = 80), and from patients with P. vivax infection with or without symptoms (n = 124). An ELISA test was performed to assess the IgG anti-An. darlingi SGS. (A) Box plot graphs of IgG serum levels from non-infected individuals and from patients with P. vivax infection. Lines of the boxes represent 75th percentile, median and 25th percentile of the individual average OD values; whiskers represent the maximum and minimum values. Differences between groups were tested using Mann Whitney test. (B) ROC curve evaluating the threshold value of anti-SGS that separates non-infected individuals from P. vivax infection. Area under curve (AUC) calculated, together with the cut off value, which presents the higher likelihood ratio, and p values are plotted.