An easy-to-perform immunologic test for histoplasmosis is described.
The test, involving precipitin reactions in agar gel, appears to have greater sensitivity and specificity than currently available tests for histoplasmosis. It is useful in the study of small or large numbers of patients.
It has been possible to demonstrate at least one antigen common to H. capsulatum, B. dermatitidis, and C. immitis. This antigen may be responsible for cross reactions. Instances are cited wherein problems of cross reactions and false-positive reactions have been clarified by means of precipitin-in-gel studies.
Precipitin reactions in agar have provided presumptive diagnosis of histoplasmosis in a patient with acute pericarditis, which rapidly progressed to constrictive pericarditis necessitating pericardiectomy.
Patch testing with aluminium Finn Chambers could give false positive reactions in patients with contact allergy to aluminium
