Comp Clin Pathol (2012) 21:1183–1185 DOI 10.1007/s00580-011-1258-8
ORIGINAL ARTICLE
Prevalence of bovine viral diarrhea virus antibodies in dairy cattle herds in the suburb of Kerman, Iran Mohammad Khalili & Mohammad Mehdi Molaei & Ali Asghar Mozaffari & Fatemeh Dorreh Giraei & Nasiri-far Ehsan
Received: 16 December 2010 / Accepted: 6 April 2011 / Published online: 15 April 2011 # Springer-Verlag London Limited 2011
Abstract Sixty-five samples of bulk tank milk were obtained from the largest milk processor in Kerman. All the samples were tested by a commercially indirect ELISA for the detection of anti-bovine viral diarrhea virus (BVDV) antibodies. On the basis of serological results, dairy farms were assigned in four classes (0, 1, 2, and 3). Among these, 38 farms (58.46%) had a moderate to high level of antibody (2 or 3 classes) indicating that there was a possible BVDV infection, or they had recently been infected with BVDV. This is the first study on seroprevalence of BVDV in Kerman dairy farms which shows that the BVDV infection is wide in industrial dairy cattle herds in Kerman.
M. Khalili Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran M. Khalili (*) International Centre for Science and High Technology and the Environmental Sciences, Mahan, Iran e-mail:
[email protected] M. M. Molaei : A. A. Mozaffari Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran F. D. Giraei Graduated from School of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran N.-f. Ehsan Department of Animal Sciences, Genetic and Animal Breeding, School of Acriculture, Azad University of Karaj, Tehran, Iran
Keywords BVDV . Bulk tank milk . Cattle . ELISA . Kerman
Introduction Bovine viral diarrhea (BVD) is a worldwide distributed infectious disease of cattle caused by the bovine viral diarrhea virus (BVDV), a member of the pestivirus genus within the Flaviviridae family (Pringle 1999). BVDV infections involve mainly respiratory, enteric, or reproductive organs like an increased risk of placental retention and clinical mastitis; a higher requirement for estrus-stimulating treatments and longer calving intervals have been described in dairy herds with a high prevalence of seropositive cows, thus causing considerable economic losses in cattle farming (Nettleton and Entrican 1995; Niskanen et al. 1995). Acute infections also induce a variable degree of immunosuppression, which may potentiate secondary bacterial and viral diseases of the respiratory and enteric tracts of persistently infected (PI) individuals. PI animals generally remain lifelong virus carriers, shedding large quantities of virus in most bodily excretions and secretions (Alenius, et al. 1996). Our purpose of this study was to determine the prevalence of BVDV infection in Kerman dairy farms. This is the first study on seroprevalence of BVDV in Kerman dairy farms.
Materials and methods Cattle herds and study area At present, Kerman has a total of 65 dairy cattle flocks, which corresponds to a population of 7,500 animals in location at the time of sampling. Herd size ranges between 8 and 360 cows. All of the dairy cattle herds located in Kerman, the biggest province of Iran, were
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studied. The region studied is 181,785 km in size and the maximum altitude is 1,755 m above sea level. During the whole year, Kerman has very low levels of precipitation and in the winter the climate is mild. Samples Sixty-five samples of bulk tank milk were obtained from the largest milk processor in Kerman (Kerman Pegah Industry). Fifty milliliters of samples were collected without preservative during a 24-h period in July 2009. An aliquot of skimmed milk was prepared from each sample by centrifugation at 1,800×g for 15 min at 4°C, and the aliquots were stored at −20°C or below until enzymelinked immunosorbent assay (ELISA) test. Serology test Commercial indirect ELISA kits (BVD-Ab; SVANOVA Biotech, Sweden) with microtitre plates coated with respective antigen were used for the detection of antibody against BVDV in bulk milk samples according to the instructions of the manufacturer. The optical densities (ODs) were measured at 450 nm with an ELISA reader (Anthos 2020, Austria). All ODs were corrected before interpretation of the results by subtracting the ODs for the control antigen from the OD sample (ODcorrected=ODsample−ODcontrol. On the basis of the corrected optical density (COD), percent positivity (PP) of each herd calculated (PP=COD sample/ COD positive control×100). On the PP, herds were classified according to the classification scheme used in the Swedish eradication program (Alenius et al. 1996). Herds were assigned to class 0 if the PP=0–2, to class 1 if 2
