The enterotoxemia complex in Andean neonatal alpacas

Abstract Background : Enterotoxemia-induced mortality has a strong negative impact on the Peruvian alpaca industry, but very little is known about the etiopathogenesis of this disease, and in Peru it has been exclusively attributed to Clostridium perfringens without consideration of other possible causes. Methodology : A national survey of 22 different communal and small herds from the main alpaca producing Departments of Peru identified 132 animals with typical lesions of the disease and microbiological and molecular analysis of 307 isolates and histopathology of 108 selected intestinal tissues were completed. Native supernatants from 24 isolates (12 vegetative and 12 sporulated) were evaluated to characterize alpha toxin, perfringolysin and hemolytic production, in vitro cytotoxicity and in vivo enterotoxicity activities of the alpha toxin. Results : Microbiological and molecular analysis of 307 isolates found that 93.5% (n = 287) corresponded to Clostridium perfringens type A ( cpa gene), 6.2% (n = 19) to genotype A cpb2 + (both cpa and cpb 2 genes) and only one isolate was type C genotype harboring the cpe (enterotoxin). Most vegetative isolates had high and medium alpha toxin production profiles (n = 8), whereas 11 of the 12 sporulated isolates were low producers. The high alpha toxin producer strains (n = 5) were cytotoxic to HEp2 cells and had the highest hemolytic and perfringolysin activities and induced intestinal fluid accumulations, but none of the isolates produced intestinal lesions similar to enterotoxemia. The histopathological study of 108 intestinal samples, however, revealed that 30.6% of the necrotic and hemorrhagic enteritis lesions also had abundant immature structures of Eimeria macusaniensis affecting deep mucosa and cryptic gland epithelia, primarily in the jejunum and ileum. Conclusions : The role of C . perfringens type A in neonatal enterotoxemia remains elusive and still needs to be clarified, but histopathological study suggests that eimeriosis may be a triggering or predisposing factor for the development of the disease. To fully understand the pathogenicity of the disease it is necessary to keep searching for C . perfringens virulent strains and virulence factors, including toxins, enzymes, and especially predisposing factors including microbial, management and/or nutrition responsible for intestinal dysbiosis.