Development of Dirofilaria scapiceps (Leidy, 1886) (Nematoda: Filarioidea) in lagomorphs

Abstract

Development of Dirofilaria scapiceps (Leidy, 1886) was followed in 34 experimentally infected cottontail rabbits (Sylvilagus floridanus). Worms were recovered from all rabbits and intensity ranged from 8 to 76% of the number of infective larvae inoculated. Development to subadults occurred in subcutaneous tissues in various regions of the body; the specific region was influenced by the site of inoculation. The third and fourth moults occurred at 6 and 12 days postinoculation, respectively. Subadults migrated through the subcutaneous tissues and arrived in the ankles as early as 16 days postinoculation. Worms were sexually mature by 67 days. The prepatent period was 137–234 days and the microfilaraemia was nonperiodic. Few worms in cottontail rabbits degenerated or died and rabbits with 1-year-old infections could be reinfected. Dirofilaria scapiceps was recovered from 12 of 14 experimentally inoculated snowshoe hares (Lepus americanus) and 2 of 4 New Zealand white domestic rabbits (Oryctolagus cuniculus). Intensity in snowshoe hares and domestic rabbits ranged from 0.4 to 15% and 6 to 7%, respectively, of the number of infective larvae inoculated. Many worms in these hosts degenerated or died.