Analysis of the epidemiological variables associated with a high prevalence of bovine surra in the Chhattisgarh state of India

Trypanosoma evansi, a unicellular haemoflagellate, causes surra in bovines and other economically important livestock species. We report here the epidemiological variables associated with the high prevalence of T. evansi infection in cattle in the plain agro-climatic zone of Chhattisgarh state, India. A total of 920 blood and sera samples were tested by a combination of parasitological, molecular and serodiagnostic tests. An overall prevalence of T. evansi was recorded as 4.57% (95% CI: 3.22-5.92%), 6.09% (95% CI: 4.54-7.63%), 63.91% (95% CI: 60.81-67.01%) and 55.33% (95% CI: 52.12-58.54%) by direct microscopy, PCR, ELISA and IFAT, respectively. The Chi-Square test established a significant correlation between the prevalence of T. evansi and the season, breed and place of the study, while the association with the gender and age of the animals was insignificant. The analysis of the prevalence ratio revealed a significant association of the breed, season and place of study with the prevalence of T. evansi. As per PR _observed, the prevalence was 1.63 times higher in summer and 1.68 times higher in the rainy season than in the winter (reference season). The prevalence was higher in all the districts as compared to Rajnandgaon (reference district). The prevalence ratio in Sahiwal and HF cross-breed cattle was significantly higher than the Gir breed of cattle (reference). Durg district recorded the highest prevalence of surra, and the difference was significant. The medium IFAT titre, determined in a large number of sera collected from Durg, predicted a higher incidence of trypanosomosis in that district. Since T. evansi has a broad host range, the study predicted that a large population of livestock in Chhattisgarh state were at high risk of T. evansi infection. Treatment of the subclinically and clinically infected animals with selective curative drugs, such as diminazene aceturate, isometamidium chloride or the combination of quinapyramine sulphate and quinapyramine chloride, could help restore productivity and help in containing the infection.