Results for IgG/IgM titres (NTU) were classified as ‘positive/infection’ when IgG+ >55 and/or IgM+ >11, ‘borderline’ when IgG+− 50–55 and/or IgM+− 9–11, and ‘negative’/no infection when IgG− <50 and /or IgM− <9. This evidence concerns the gene CD40LG and infection.