Prevalence of bovine leukemia virus (BLV) infection in the northeast of Iran

The purpose of this study was to determine the prevalence of bovine leukemia virus (BLV) in Khorasan Razavi and Khorasan Shomali provinces which are the main provinces located in the northeast of Iran. Total number of ۴۲۹ blood samples were collected from industrial dairy herds. The samples were categorized based on province, age (۲-۳, ۴-۶, and ۷-۱۰ years old), calving (≤ ۲, ۳-۵, and > ۵) and herd size (≤ ۱۰۰, ۱۰۱-۲۵۰, and > ۲۵۰) and examined by indirect ELISA. The results of this study showed that ۱۰۹ (۲۵.۴%) out of ۴۲۹ serum samples were BLV seropositive. The BLV prevalence among cattle of dairy herds of Khorasan Razavi and Khorasan Shomali provinces were ۲۹.۸% and ۱.۵%, respectively. The results showed that the number of seropositive animals was increased significantly with the age (p < ۰.۰۵). The infection rate in animals ۲-۳, ۴-۶ and ۷-۱۰ years old were ۱۲.۱%, ۲۶.۷% and ۴۵.۶%, respectively. It was shown that BLV prevalence according to calving ≤ ۲, ۳-۵ and > ۵ was ۱۵.۵%, ۳۳.۰% and ۴۲.۹%, respectively, with a significant difference between calving ≤ ۲ and > ۵ (p < ۰.۰۰۱). The prevalence of BLV among herd size of ≤ ۱۰۰, ۱۰۱-۲۵۰ and > ۲۵۰ was ۱۹.۷%, ۱۴.۳% and ۴۲.۱%, respectively, which was significantly higher in herds with more than ۲۵۰ cattle (p < ۰.۰۵). This study revealed that BLV infection in dairy herds of northeast of Iran was influenced by geographical location (province), age, calving and herd size.

کلیدواژه ها:

Bovine leukemia virus ، Dairy cattle ، Indirect ELISA ، Iran ، Prevalence