Epidemiological Measures of Disease Occurrence in Bluetongue

Bluetongue is a primarily midge-borne devastating hemorrhagic viral disease of sheep characterized by high morbidity and mortality resulting severe economic losses to sheep farmers. An epidemiological study was undertaken to assess the crude and specific measures of morbidity, mortality and case fatality against bluetongue in sheep. In this study, a total of 11 bluetongue outbreaks were selected by active and passive surveillances in north-west agroclimatic zone of Tamil Nadu, India. Overall morbidity, mortality and case fatality rates were 6.15 %, 3.31 % and 53.82 % respectively. Morbidity, mortality and case fatality rates were higher in adults than young animals. Morbidity, mortality and case fatality rates were higher in Mecheri breed than Trichy black and Non-descriptor. Difference in disease frequency was not observed between males and females. The present study concludes age and breed predisposing exist in the outbreaks of bluetongue.