Yoshinori Kawabata

Human pulmonary dirofilariasis with special reference to the ELISA for the diagnosis and follow-up study

Since the importance of Dirofilaria immitis as a causative agent of solitary nodules or coin lesions in the human lung was demonstrated (Beaver and Orihel 1965), more than 100 cases have been reported in literature in the United States (review, Ciferri 1982) and in Japan (review, Yoshimura 1980). The current increase in number of reports on dirofilariasis involving various tissues other than the lung (Tada et al. 1979; Kaneda et al. 1980; Takeuchi et al. 1981), as well as a case in Okinawa with a subcutaneous nodule due to D. repens infection (MacLean et al. 1979), has drawn attention to the infection in Japan. However, little work has been done on immunodiagnostic tests for dirofilariasis (Ciferri 1982) mainly because differential diagnosis has been possible only by postoperative and histological examination. There is only one reported immunological study, which includes the skin test, agar-gel diffusion and immunoelectrophoresis leading to preoperative diagnosis (Tamaoki et al. 1978). The purpose of the present communication is to describe the application of the enzyme-linked immunosorbent assay (ELISA) for the diagnosis and also for a follow-up study of dirofilariasis. A 54-year-old teacher living in Tokyo who had been in excellent health and was admitted to a hospital on 21 July 1981 after a routine check revealed a nodular shadow in the lower field of his right lung. Re-examinations of the chest confirmed the shadow and the preoperative diagnosis of benign tumor was made. At a chest operation carried out on 27 August 1981, a soft mass of 30 by 20 mm was found in the peripheral interlobar space of the right S 8 . The mass was removed and histological examinations were carried out to demonstrate seven transverse sections of worms surrounded by organizing thrombi in the pulmonary artery of the tissue with coagulative