Long‐Term Clinicopathological Characteristics of Alpacas Naturally Infected with Bovine Viral Diarrhea Virus Type Ib

Journal of Veterinary Internal Medicine

D. Bedenice¹  E. Dubovi²  C.L. Kelling³  J.N. Henningson³  C.L. Topliff³ 

[1]Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA

[2]Department of Population Medicine and Diagnostic Science, Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, Ithaca, NY

[3]Department of Veterinary and Biomedical Sciences, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE

关键词: Bovine viral diarrhea;    Camelid;    Persistent infection;   

DOI  :  10.1111/j.1939-1676.2011.0719.x

来源: Wiley

【 摘 要 】

Abstract

Background: Substantial bovine viral diarrhea virus (BVDV)-related production losses in North American alpaca herds have been associated with BVDV type Ib infection.

Objectives: To classify and differentiate the long-term clinicopathological characteristics of BVDV type Ib infection of alpaca crias, after natural virus exposure. We hypothesized that persistently infected (PI) alpacas specifically demonstrate growth retardation, clinicopathological evidence of opportunistic infections, and early mortality.

Animals: Thirty-five crias naturally exposed to BVDV (18 acute, 3 chronic, 14 PIs), and 19 healthy cohort controls of 5 northeastern alpaca farms were prospectively evaluated over 2 years (September 2005–September 2008).

Methods: Observational cohort-control study.

Results: Chronically (viremia >3 weeks) and PI crias demonstrated significantly lower birth weights, decreased growth rates, anemia, and monocytosis compared with control animals. Common clinical problems of PI alpacas included chronic wasting, diarrhea, and respiratory disease. Median survival of PI alpacas that died was 177 days (interquartile range, 555) with a case fatality rate of 50% within 6 months of life. Transplacental infection was confirmed in 82% (9/11) of pregnant females on 1 farm, resulting in the birth of 7 PI crias (7/10 deliveries; 1 animal was aborted). Mean gestation at the beginning and end of BVDV exposure was 64 and 114 days, respectively.

Conclusions and Clinical Importance: Natural BVDV type 1b infection during early pregnancy resulted in a high incidence of PI offspring. Although PI alpacas may have distinct clinical characteristics, verification of persistent viremia in the absence of endogenous, neutralizing antibodies is essential to differentiate persistent from chronic infection.

【 授权许可】

Unknown   
Copyright © 2011 by the American College of Veterinary Internal Medicine