- Bovine Viral Diarrhea (BVD) is an emerging disease in both New World Camelids (NWCs) and Old World Camelids (OWCs). The virus has been isolated from NWCs particularly in alpacas and dromedaries, but there are no reports of BVD in Bactrians. BVD is an important infectious disease. Both sub-genotypes 1a, 1b and genotype 2 have been isolated from NWCs but the ncp BVDV 1b is primarily implicated in cases of BVD in NWCs. A BVD strain unique to camelids has not yet been isolated. In NWCs virtually all infections have been caused by the non-cytopathic (ncp) BVDV, Persistently infected crias have also been detected. Llamas and alpacas demonstrate clinical signs such as ill thrift, diarrhea, respiratory ailments and abortions. As in bovines, identification and elimination of PI animals, has the highest priority to avoid infection of the entire herd. BVD was also observed in dromedaries and interestingly, both genotypes of the Pestivirus, BVDV-1 and BVDV-2, were isolated from dromedaries in Egypt. Both isolates revealed a cytopathic effect (cpe) and so far no ncp virus has been isolated from dromedaries. Also in dromedaries, BVD infections caused intrauterine death, stillbirth, weak calf syndrome with congenital deformities, neonatal respiratory disorders in young dromedary calves and acute hemorrhagic gastroenteritis in adult dromedaries. So far, no PI dromedaries have been described.
Comparison of Clinical, Hematological, and Virological Findings in Alpacas (Lama pacos) Inoculated with Bovine Viral Diarrhea Virus Isolates of Alpaca or Bovine OriginClinical evidence demonstrates that alpacas may contract and propagate bovine viral diarrhea virus (BVDV). The objective of this research was to compare and characterize clinical signs, hematological findings, viremia, and seroconversion resulting from intranasal inoculation of alpacas with BVDV 1b and BVDV 2 isolates from cattle and a BVDV 1b isolate of alpaca origin. Three groups of six alpacas were intranasally inoculated with a different isolate (Group 1: BVDV 1b of bovine origin; Group 2: BVDV 2 of bovine origin; Group 3: BVDV 1b of alpaca origin). Following inoculation, all three genotypes induced viremia, nasal shedding and seroconversion in naïve alpacas. The onset of viral detection in serum was significantly different among groups; the median onset was 4, 2, and 7 days for Groups 1, 2, and 3, respectively. Onset of viral detection in white blood cells was significantly different with median onset at 3, 2, and 4 days, and median cessation at 13, 9, and 13 days, respectively. The median onset of viral nasal shedding was 8 days and was not significantly different between groups. Virus was detected after inoculation until a median of 8 days in nasal secretions, 10 days in serum, and 12 days in white blood cells. A reduction in mean total leukocytes was observed in all three groups when compared to pre-inoculation leukograms. Results demonstrate that BVDV 1b and 2 strains cause alpacas to exhibit viremia and nasal shedding of virus in a temporal pattern that is similar to the outcome of acute infection of cattle.
Knowledge Gaps Impacting the Development of Bovine Viral Diarrhea Virus Control Programs in the United StatesInfections with BVDVs result in major economic losses for beef and dairy producers worldwide. The success of control efforts in Scandinavia has led to a consensus that BVDV eradication in Europe is a realistic goal.
- Bovine virus diarrhea virus (BVDV) has recently been identified as an important infectious disease of new world camelids (NWC) particularly alpacas. Both sub-genotypes 1a, 1b and genotype 2 have been isolated. However, non-cytopathic BVDV 1b is reported to be primarily implicated in cases of BVDV in NWC's. Although suspected a BVDV strain unique to camelids have not been isolated. The most important source of BVDV is the immuno-tolerant persistently infected cria. Natural transient infection of BVDV in NWCs is reported to go almost undetected except for vague signs of illness, including lethargy and anorexia. Diarrhea does not appear to be a constant finding. Embryonal/fetal disease in NWC's includes early pregnancy loss, abortion and premature birth or the birth of persistently infected crias. Persistently infected disease can occur in both acute and chronic forms. In NWCs the chronic form of the condition is most commonly reported. Signs include chronic ill-thrift, poor weight gain or being underweight, intermittent illness, chronic diarrhea, joint swelling and episodes of nasal discharge and pneumonia despite antibiotic treatment. The mortality rate in NWCs appears to be close to 100%. Seroprevalence of BVDV in NWCs ranged from 2.05% to 11.11% however the possibility that the correct (homologous) BVDV strain is not being used in serological assays need to be considered. The importance of cattle as a source of BVDV for camelids is unclear although there is consensus of a spill-over from cattle to NWC's. Assays available for BVDV in cattle appear to work for camelids. An antigen ELISA which is the usual method for detecting BVD in cattle has not been validated in NWC's.
- Clinical Findings—In addition to pyrexia and clinical signs of disease of the upper portion of the respiratory tract, the cria had inappetence and was in an unthrifty condition. Hematologic abnormalities included low WBC count, low hemoglobin concentration, and low PCV. Samples of blood were submitted for bovine viral diarrhea virus (BVDV) isolation and serologic evaluation. Other adults and newborn crias in the herd were similarly examined. Bovine viral diarrhea virus was detected in the cria, and a diagnosis of persistent infection with BVDV was made at 5.5 months of age. Persistent BVDV infection was suspected in another cria born into the herd but was not identified in any of the adult alpacas. Treatment and Outcome—Despite several treatments with antimicrobials, no permanent improvement of the cria's condition was achieved. Because of the poor prognosis, the owners requested euthanasia of the cria; BVDV was isolated from specimens of multiple organs collected at necropsy. Clinical Relevance—To date, BVDV infection in New World camelids has not been regarded as a major disease entity. Findings in the cria of this report illustrate that some strains of BVDV readily infect alpacas. Clinical description of the disease plus clinicopathologic findings suggest that persistent BVDV infection may be greatly overlooked as a cause of chronic anemia and failure to thrive in alpacas.