Seroepidemiology of Leptospira interrogans Infection in Ruminants of Lorestan Province: A Cross-Sectional Study

Leptospirosis is a common bacterial disease in humans and livestock, which leads to reduced production and reproductive disorders in ruminants and also causes major economic losses to villagers and farmers.

The purpose of this study was to investigate the seroprevalence of different Leptospira interrogans serovars in ruminants population of Lorestan province and assess the role of environmental and host factors on the severity of the serological infection.

For this purpose, referring to livestock and sheep and goat flocks in different cities of Lorestan province, 691 blood samples were collected including 258 sheep, 195 goats and 238 cows, and then, the point of infection with seven different serovars of Leptospira interogans was assessed using microscopic agglutination test. Hosting factors such as age, gender and also environmental factors including geographical area, rainfall, temperature, relative humidity and altitude of sampling area from the sea level were recorded, and their probable role in the seroprevalence was statistically analyzed.

Results of this study showed that the overall prevalence of leptospirosis in cattle, sheep, and goats examined in the Lorestan province was 26.05 % (95 % CI: 19.7-31.23), 22.48 % (95 % CI: 16.95-25.16) and 14.87% (95 % CI: 9.37-20.36), respectively. There was no statistically significant (p < /em>>0.05) difference from the point of age groups and sexes. The most prevalent contaminant serovars for cows, sheep, and goats with seropositive reaction against leptospira were grippotyphosa (41.93%), canicola (32.76%) and canicola (48.27 %), respectively. The results showed environmental factors including relative humidity (p < /em>=0.02), annual rainfall (p < /em>=0.001) and altitude from the sea level of sampling location (p < /em>=0.03) have a significant effect but the annual temperature does not have a significant effect (p < /em><0.05) on the seroprevalence of Leptospira. Also, more positive reactive animals in the eastern and western areas of Lorestan province were found (p < /em>>0.05).

Leptospirosis is endemic in livestock population of Lorestan province and environmental factors play a significant role in the severity of infection, which increases the need for attention to the geographical areas at risk.