Strongyloidiasis (Strongyloides papillosus) in lambs in Uruguay

Here, we describe a spontaneous outbreak of strongyloidiasis (Strongyloides papillosus) in sheep in Uruguay. In a flock of 150 lambs, 60 animals became ill and 12 died within 3 weeks. Affected animals showed weakness, weight loss, enophthalmos and, in some cases, sudden death. Postmortem examination revealed muscle atrophy, dehydration, and small intestines with a foamy and liquid content. Histological examination of the duodenum and the jejunum showed a thick mucosa with severe villous atrophy, mononuclear mixed infiltrate in the lamina propria, and a large number of nematodes embedded in the mucosa, with numerous granulomas in the lamina propia. Small intestinal content analysis showed a total of 13,200 female nematodes in the duodenum and 2000 in the jejunum, identified as Strongyloides papillosus (Strongyloididae). This parasite has long been considered to behave as a commensal parasite or at least to cause significant disease only when present in large numbers. This report shows that Strongyloides papillosus can be highly pathogenic in sheep.