Serologic study on leptospiral infection in sheep in Ahvaz, southwestern Iran

To investigate the seroprevalence of leptospiral infection in sheep in Ahvaz, southwestern Iran, blood
samples were taken from 181 female sheep. Sera were stored at -20°C until use. They were initially screened
at serum dilution of 1:100 against six live antigens of Leptospira interrogans serovars pomona, canicola,
hardjo, ballum, icterohaemorrhagiae, grippotyphosa using the microscopic agglutination test (MAT). The
samples were considered positive if ≥ 50% of agglutination of leptospire in a dilution test serum of ≥ l:100
were observed. Sera with positive results were titrated against reacting antigens in serial two-fold dilutions
from l:100 to 1:1600. Antibodies against one or more serovars were detected in 27 (14.9%) sera at dilution
≥1:100. Antibodies against more than one serovar were found in 5 (18.5%) positive sera. Among the positive
sera, antibodies were most frequent to serovar pomona (43.8%) followed by canicola (21.9%),
icterohaemorrhagiae (12.5%), grippotyphosa (9.4%), ballum and hardjo (each of them 6.3%). The results of
this survey indicate that leptospiral infection is common in sheep in Ahvaz and that various serovars concur
in the etiology.