Parasitic gastritis in a llama (Lama glama) associated with inhibited larval Teladorsagia spp. (Nematoda: Trichostrongyloidea).

A 7-year-old female llama was experimentally infected with 500 Fasciola hepatica metacercariae then turned out onto pasture also grazed by domestic sheep. The llama was necropsied approximately 22 weeks post infection. Routine examination of the gastrointestinal tract revealed diffusely coalescing, umbilicated nodules covering the caudal one-fifth of the third stomach compartment. Microscopically, the mucosa was irregularly thickened. Numerous nematode larvae were present in glandular lumens, often extending to the base of the glands. Where nematodes were most numerous, decreased numbers of parietal cells, attenuation of glandular epithelium and increased collagen within the lamina propria were evident. Of a total of 6510 adult nematodes in the third stomach compartment, 51% were Teladorsagia spp., 47% were Trichostrongylus axei, and 2% were Camelostrongylus mentulatus. Except for C. mentulatus, three sheep that had grazed with the llama and were necropsied at approximately the same time, harbored the same nematode species. The total number of larvae in the llama was 56,710, with more than 97% being ostertagiine early fourth-stage larvae. Ostertagiine larvae were also present in the sheep. Based on the composition of the adult populations in the llama and sheep, the larvae were considered to be species of Teladorsagia. Additionally, the larger numbers of early fourth-stage larvae indicated that the development of Teladorsagia spp. in the llama is inhibited.