Serological survey of leptospirosis in sheep in Bosnia and Herzegovina

Leptospirosis, a reemerging zoonotic disease caused by pathogenic bacteria of the genus Leptospira, affects a wide range of domestic and wild animals. The only investigation into sheep leptospirosis in Bosnia and Herzegovina was conducted nearly 50 years ago. This study aimed to assess the seroprevalence of leptospirosis and to identify the most common serovars in sheep in Bosnia and Herzegovina, using the microscopic agglutination test (MAT). Leptospirosis seroprevalence was determined to be 2.16% at a cut-off titer of ≥1:100 (55/2542) and 8.10% at a cut-off of ≥1:25 (206/2542), with all positive cases related to a single serovar. The MAT titers were 1:25 and 1:100, with the majority of positive animals having low titer (1:25) (151/206; 73.3%). At a cut-off of ≥1:100, the sera most frequently reacted to Pomona (54.55%) and Hardjo (27.27%), and less commonly to Saxkoebing and Icterohaemorrhagiae (0.2%) (P<0.05). Odds of seropositivity were higher for Pomona and Hardjo than for Saxkoebing and Icterohaemorrhagiae. The results of this study showed for the first time in Bosnia and Herzegovina, the presence of serovar Icterohaemorrhagiae in sheep, with Pomona and Hardjo as the dominant serovars. Although the seroprevalence is low, the potential zoonotic risk requires continuous monitoring and control strategies to prevent the spread of leptospirosis.