IgM against scrub typhus seems to peak early in the infection (5.2 days) and wanes rapidly.19,20 Using data from Thailand and India, Aiemjoy et al. and Schmidt et al. have shown that after 5.3 months19 and 2.7 months20 50% of participants had IgM OD of <1, respectively. Here, CD40LG is linked to infection.