Dirofilaria repens infection in northern Israel

The fourth case of zoonotic Dirofilaria repens infection in Israel is reported, and the diagnostic morphologic characteristics of this filariid are reviewed. The importance of the exact anatomic diagnosis of this filaria is stressed in view of the fact that Israel has pockets of settlers from East Africa, a region endemic for lymphatic filariasis (Wuchereria bancrofti). Since the possibility of introduction of such an infection into the country exists, differentiating this zoonotic Dirofilaria from other filarial worms is essential. The clinicopathological features of a Dirofilaria repens infection are distinct. The patient initially has a painful subcutaneous or conjunctival swelling; the excisional biopsy shows the presence of a dead or alive, usually female worm that measures 220-660 microns across; the central intestine and the genital organs (two uteri) are located in the pseudocoelom; the thick, multilayered cuticle is provided with 95-105 sharp, longitudinal ridges, the latter being separated from each other by a distance of 12 microns; the circumferential muscle cell layer, covering the inner side of the cuticle, is bilaterally interrupted by the large chord cells, two to five nuclei of which are discernible in each cross section.