CD40LG and infection: The serologic diagnosis of acute infection is based on detection of DENV-specific immunoglobulin M (IgM), detectable in 93% of cases, 6 to 10 days after the onset of fever.(8) Dengue virus-specific immunoglobulin G (IgG) can be detected in current infections if, at the time the test is performed, seroconversion has already taken place, and is otherwise useful to check for past infections.