Clinical, parasitologic, and immunologic observations of patients with hydrocele and elephantiasis in an area with endemic lymphatic filariasis.

Hydrocele and elephantiasis, major clinical manifestations of bancroftian filariasis, are thought to share a common pathogenesis. The characteristics of 121 patients with hydrocele or elephantiasis in Leogane, Haiti, were compared: 39% of 57 men with hydrocele and 3% of 64 persons with lymphedema of the leg were microfilaria-positive (P < .001). Circulating filarial antigen, presumably from the adult worm, was detected in 15 (43%) microfilaria-negative men with hydrocele and 9 (15%) microfilaria-negative persons with leg edema (P = .004). Microfilaria-positive men had lower levels of filaria-specific IgG1 and hydroceles of significantly smaller volume and shorter duration than did microfilaria-negative men; hydrocele volume was inversely associated with microfilarial density (P = .001). In contrast, filarial antigen but not microfilariae was associated with filaria-specific IgG4 and decreased lymphocyte proliferation. Antigen status was not associated with severity of leg edema. In this filariasis-endemic area, men with hydrocele are more immunologically and parasitologically heterogeneous than are persons with elephantiasis.