-

Objective: To determine serological prevalence rate of infection
of sheep with IBR virus in Chaharmahal-Bakhtiary province.
Design: Cross - sectional study. Animals: Four hundred and two healthy sheep. Procedure: Serum samples were collected from 402 sheep during
four seasons of 2002-2003 in all townships of Chaharmahal -
Bakhtiary province by cluster random sampling method.
Charactristics of the animals (age, sex and history of abortion) were
recorded. Sera were tested for antibodies against IBR virus by the serum neutralization test.
Statistical analysis: Chi-square, Linear regression.
Results: Serum samples from 43 (10.7%) sheep were positive. Prevalence rate of seropositive animals in all 5 townships of the
province was estimated. No relationship was found between township, sex, season, previous record of abortion and IBR infection
in sheep. Linear regression test indicated a relationship between
age and prevalence rate of infection (r = 0.94).