The presence of IgG antibodies generally indicates past exposure and immunity.20 Serological screening for both IgM and IgG throughout the time-course of infection could increase diagnostic accuracy, help monitoring course disease during and after treatment, and help identify reservoirs that may amplify outbreaks.12 The advantages of serological IgG–IgM combined antibody tests are that they are material and time-saving tools, suitable for testing large samples, require no specialized equipment or technique and can be performed by most hospital or clinic laboratories. This evidence concerns the gene CD40LG and infection.