Lung tissue taken at biopsy from 26 patients with tropical eosinophilia showed microfilariae, indistinguishable from Brugia malayi, in one case, eosinophilic structureless material in the center of the lesions in six cases, and parasitic segments that were probably not microfilariae in two cases. The animal origin of these filariae is favored in the etiologic role of microfilariae. The possibility that nonfilarial parasites play a role in the etiology of tropical eosinophilia in at least some cases was considered, and we suggested that endemicity of a particular parasite in a particular geographical area may be the determining factor.
Present address: Department of Pathology, University of Western Ontario, London, Ontario, Canada. Please address requests for reprints to Dr. Joshi.