Overview of serology and antigen tests in acute pulmonary histoplasmosis

Histoplasma capsulatum antigen (Ag) can be detected in patients with acute pulmonary histoplasmosis and is found more commonly in patients with severe clinical manifestations. Detection of high titers of complement fixing antibodies to the yeast or mycelia antigen precedes detection of M or H bands by immunodiffusion in most patients. However, antibodies rarely appear before the fourth week of infection and often do not reach maximal titers until the second or third month of infection.