Naturally occurring parasitic bronchitis in red deer: effect of vaccination using live bovine lungworm vaccine

Natural and experimental nematode infections in red deer (Cervus elaphus elaphus) and the potential for antemortem serodiagnosis of the tissue worm Elaphostrongylus cervi

Red deer (Cervus elaphus elaphus) were exposed to a variety of nematodes, either naturally on pasture (n = 12) or experimentally under controlled conditions (n = 30). Experimental exposures included a combination of one or more of Elaphostrongylus cervi, Dictyocaulus sp., and Muellerius capillaris. The prepatent period of E. cervi infections was 92–133 days post exposure (dpe) in 12 deer each given 20–42 infective larvae (L3) and maintained under controlled conditions. Adult E. cervi were recovered from all 12 animals at necropsy. The prepatent period of Dictyocaulus sp. was 23–37 dpe in 10 deer each given 100 L3 and maintained under controlled conditions. Adult Dictyocaulus sp. were recovered from seven animals at necropsy. No animal exposed to 42–54 M. capillaris L3 developed patent infections, nor were adult worms recovered at necropsy. There was no evidence of neurologic signs in any deer at any time during the experiment. An enzyme-linked immunosorbent assay (ELISA) using somatic protein extracts of adult E. cervi or those from the closely related nematode Parelaphostrongylus tenuis was evaluated. Although the ELISA was sensitive, it lacked specificity with heterologous infections. However, the close phylogenetic relationship of E. cervi to P. tenuis, and our ELISA results, suggest that molecules from P. tenuis may represent a viable alternative source for use in the future development of a reliable antemortem serodiagnostic assay for E. cervi.

A model for study of lungworm (Dictyocaulus sp.) and gastrointestinal nematode infection in young red deer (Cervus elaphus)

A model of sub-clinical parasitism in young red deer, using concurrent trickle infections of lungworm (Dictyocaulus sp.) and mixed gastro-intestinal (GI) nematodes of deer-origin was evaluated. 20 parasite-free deer calves were artificially reared indoors from 4 days of age. A further five calves were naturally reared on pasture with their dams, treated with anthelmintic and brought indoors at 3-4 months. At 4-4.5 months of age they were individually housed and allocated to five groups (n=5). Groups were dosed 3 x per week, for 9 weeks with 0, 100 and 500, 200 and 1000 (2 groups), 400 and 2000 infective larvae of lungworm and mixed GI nematodes, respectively, cultured from deer faeces. Liveweight and voluntary feed intake measurements and faecal and blood samples were taken weekly. In the fourth week following cessation of trickle infection, deer were euthanased and lung and GI nematodes recovered. Both lungworm and GI nematode infections became patent at Week 4 of infection. Maximum group arithmetic mean faecal egg counts were 100-190 epg. Maximum group arithmetic mean faecal lungworm larval counts were 58-123 lpg. Group arithmetic mean nematode counts at slaughter ranged from 439-806 for GI nematodes and 31-73 for lungworm, respectively. Despite low nematode counts, reduced liveweight gain, voluntary feed intake and serum albumin concentration, elevated serum pepsinogen, gastrin and globulin concentrations and elevated peripheral eosinophil counts and slight haemoconcentration, but no clinical signs, were observed. The reduction in liveweight gain was related to the reduction in voluntary feed intake (r2=0.83; p<0.088). Naturally-reared deer had similar liveweight gains, voluntary feed intake and nematode counts to artificially-reared deer. Thus, methods of infection to produce concurrent sub-clinical lungworm and GI nematode burdens for study of sub-clinical parasitism in young deer have been defined.