Camelids as a host of bovine viral diarrhoea virus infection — what we have learned to date

Abstract

Bovine viral diarrhoea virus (BVDV) has been associated with reproductive loss, diarrhoea, immune-suppression with increased susceptibility to opportunistic infection (such as parasitism and pneumonia), wastage and death in South American Camelids (SAC). Unidentified BVDV infection thus poses a significant threat to herd health. BVDV type 1b strains predominate in alpacas and are able to establish transplacental infection, potentially leading to persistently infected (PI) offspring in >80% of naive, pregnant alpacas naturally exposed to BVDV type Ib during early gestation. PI alpaca crias experience a high degree of morbidity and mortality in the first 6 months of life, associated with a variety of clinical disease manifestations. Peripartum phenotypic and haematological characteristics of PI crias may be clinically indistinguishable from those of chronically infected crias with extended viraemia. Low birth weight, stunted growth, anaemia, relative and absolute monocytosis are commonly observed in affected animals. PI crias may have host defense deficits similar to PI calves and experience widespread viral tissue distribution. Both clinical and epidemiological studies underscore the importance of routine BVDV-specific diagnostic testing in order to identify persistently (lifelong) and chronically infected camelids, which serve as an important source of viral spread within and between farms.