CD40LG and typhoid fever: Of the prespecified panel of non-dengue diseases for which sera from acute febrile participants were tested, only chikungunya and typhoid fever were laboratory-diagnosed by IgM positivity at incidence densities that were higher than that of dengue (10.8 [95% CI: 8.9; 13.1] and 9.1 [95% CI: 7.3; 11.2] per 100 person-years, respectively; Table 4).