CD40LG and infection: This diagnosis was confirmed by a R. africae seroconversion of patient A (titres of 1/64 in IgG and 1/16 in IgM on the convalescent serum taken one month after the symptom onset) and by a sustained positive R. africae serology for his wife (IgG titers of 1:64 and IgM titres of 1:32 on both acute and convalescent sera; IgG titers >= 1:64 and IgM titers >= 1:32 are considered indicative of infection by R. africae).