A Flock Level Analysis of an Outbreak of Natural Border Disease in Sakiz Ewes and their Progeny

Ano: 2011 | Volume: 39 | Número: 3

Autores: Kerem Ural, Bulent Ulutas, Pinar Alkim Ulutas, Mehmet Gultekin, Abidin Atasoy

Palavras-chave: border disease, sheep, sakiz ewes, flock, analysis, outbreak

Resumo Inglês:

Background: Pestiviruses cause economically important diseases in domestic ruminants worldwide. Border Disease is a
congenital viral infection of sheep, caused by a pestivirus, and is first reported in the Border region of Wales and England. The
BDV has worldwide distribution in sheep with different prevalences among countries. Vertical transmission is an important
route in the epidemiology of this virus. Infection of fetuses may cause birth of persistently infected lambs, that are viremic,
antibody negative, and are excreting virus. The disease is characterized by abortion, barren ewes, stillbirth and persistently
infected weak lambs showing neurological and dermatological signs. The economic importance of the disease is related to
reproductive failure, abortions and significantly low survival rate of affected lambs. In the present study the aim was to
describe clinical, hematological and seological aspects of natural Border disease virus (BDV) infection in a sheep flock in
Cine, Aydin. Besides we sought to elucidate the relationship between natural (active infection) and persistent BDV disease and
the serum concentration of haptoglobin (Hp) and serum amyloid A (SAA) in infected sheep
Materials, Methods & Results: Field observations were carried out in a sheep flock comprising 327 sheep with a history of an
outbreak abortion in Cine town in Aydin, Turkey. Twenty-five out of 327 sheep in the flock was monitorized by blood
sampling. The animals were selected among aborted ones, at least once, into two weeks preceeding period or with a history of
weak lambing. BDV antigen (persistent infection) was detected in 8 out of 25 sheep (32%) while antiviral antibodies (active
infection) were detected in 18 animals tested (68%). The disease was mainly characterized by abortions, stillbirth/weak lamb
and abnormal brown/black fleece pigmentation, which occurred in an epidemic form. Twentyfive sheep were related to disease
condition as detected serologically, and the ratio of the number affected to number at risk being was 17:8. The culling rate was
50% of the affected animals. Most of the affected animals were second lambing sheep (5/25, 20%). Hematological variables
did not reveal statistical difference whereas serum concentrations of Hp (P < 0.05) and SAA (P < 0.01) were significantly higher
in naturally infected sheep in contrast to persistently infected sheep with BDV.
Discussion: Clinical signs and detailed laboratory analysis related to natural Border disease outbreak have never been
reported in Turkey, although previous epidemiological studies had shown that Border disease virus infection is relatively
common in some parts of Turkey in sheep flocks and persistent Border disease virus infection had been described in apperaently
healthy sheep in Turkey. In the present study the disease was mainly characterized by abortions, stillbirth/weak lamb and
abnormal brown/black fleece pigmentation, which occurred in an epidemic form. Besides bronchopeumonia, enteritis and
conjunctivitis were detected in a limited population. Neurological signs were only observed in 2 animals. Besides persistent
infection was detected in 32% of sheep enrolled. An acute phase reaction involving Hp and SAA has been identified in the
present study. These results indicate that the monitoring of selected acute phase proteins may increase the diagnostic information
available as a result of their analyses in naturally infected sheep and persistently infected sheep with BDV.