Nodular onchocercosis of red deer in central Spain

The presence of nodular onchocercosis was investigated post-mortem in 142 red deer (11 calves, 35 yearlings and 96 adults) shot from February 1998 to January 1999, and July-November 1999 in "Quintos de Mora" (Toledo, central Spain), a game property belonging to the National Wildlife Reserves. Between 6 and 13 animals were analysed monthly by inspection for subcutaneous nodules of Onchocerca spp. Subcutaneous nodules of Onchocerca sp. were detected in 24% of the animals. Anatomical locations for nodules were the back and flanks. Infection ranged from 1 to 29 nodules per animal. Adult worms collected from nodules were identified as O. flexuosa. No apparent seasonal trend was observed either in prevalence or in mean intensity of infection, which fluctuated between 48% (5+/-8 nodules) in winter 1998 and 5% (1+/-0 nodules) in summer 1999. Prevalence of infection was significantly higher in adult (30%) than in young animals (9% in calves, 11% in yearlings), although no age effect on intensity was observed. The size of the nodules was measured to evaluate the age of infection. Small (recent) nodules (5-6mm of diameter) were collected in late spring, summer and fall; medium-sized nodules (12-15 mm) were in second half of summer, fall and winter, and large (mature) nodules (20-25 mm) in fall, winter and part of spring. Significant differences were found among host age groups.