Cytologic diagnosis of bancroftian filariasis in a nonendemic area.

Parasitic infections are common in the developing countries, but the cytologic diagnosis of such infections is infrequent or rare. This paper presents four cases of filariasis caused by Wuchereria bancrofti diagnosed by cytologic examination and discusses some unusual observations. The finding of microfilariae in pleural fluid in the absence of the classic symptoms and signs of tropical pulmonary eosinophilia is highlighted. In two patients, nocturnal microfilaremia could not be demonstrated despite Nuclepore filtration, thus suggesting the possible merits of cytology in the primary diagnosis of a filarial infection. Even the diethylcarbamazine provocative test failed to elicit a peripheral microfilaremia in one patient, further emphasizing the importance of cytology as a diagnostic method in amicrofilaremic infections. Attention is drawn to the need for a high index of suspicion on the part of the cytologist in the identification of parasitic organisms in material from high-risk groups to achieve an early diagnosis of such infections and the prompt institution of appropriate chemotherapy. This may obviate the more serious pathologic changes of advanced disease, especially the disfigurement of chronic and late filariasis.