The usefulness of immunologic methods for diagnosis and follow-up study of a case of pulmonary dirofilariasis

Abstract

Nearly 70 cases of dirofilariasis have been reported in Japan. A case operated for pulmonary dirofilariasis is reported, together with useful immunologic diagnostic and follow-up study. A 62-year-old woman was admitted to our hospital with complaints of cough and right chest pain. A chest X-ray film revealed a mass approximately 4 cm in diameter in the right S9 region. Histological examination of the mass by TBLB revealed necrotic tissue containing eosinophils and Charcot-Leyden crystals. Around the area of necrosis there was granuloma with infiltrating neutrophils, eosinophils and lymphocytes. Therefore, immunologic examinations were performed on the suspicion of a parasitic disease. Ouchterlony's test was done with positive reaction against Dirofilaria immitis antigen. Results of the ELISA indicated a high antibody titer (1:12800) to Dirofilaria immitis antigen. Histological examination of a surgically removed mass gave the final pathologic diagnosis of pulmonary dirofilariasis caused by Dirofilaria immitis. A follow-up study by ELISA revealed a remarkable decrease of the antibody titer to 1:3200 at 1 month after surgery, to 1:200 at 6 months and to negative after 9 months. These results suggest that the ELISA could be used to judge the healing of the disease by drug therapy. Thus immunologic studies by Ouchterlony's test and the ELISA were considered to be useful for the diagnosis and follow-up study of dirofilariasis.