Prevalence of bluetongue in sheep and goats across different climatic regions and zones in India: a meta-analysis.

Bluetongue (BT), an arthropod-borne haemorrhagic viral disease of domestic and wild ruminants, and its prevalence was estimated by meta-analysis. BT prevalence studies in sheep and goats were obtained from published literatures for estimating prevalence in India by using R open-source software V3.2.5 with meta package. The pooled BT prevalence was 40.9% (95% confidence interval (CI): 34.8-47.3%, 95% prediction interval (PI): 5-90%) obtained from 98 studies with 51,973 samples. BT prevalence in sheep, goat, sheep and goat were 35.7, 37.7, and 48.2%, respectively. The period-wise analysis revealed a high BT prevalence during 2011-2020 (50.5%) than other decades. Based on zone-wise analysis, a higher BT prevalence was in central zone (53.7%) and lower in west zone (34.1%). The method-wise showed a higher BT prevalence by molecular method (41.7%) and tissue was found to be suitable sample-type. BT prevalence was higher in BTV-1 (40.3%) and lower in BTV-9 (10.4%) serotypes. The monsoon type with dry season in high sun period region showed a higher BT prevalence and lower in monsoon type with short dry winter season was observed. The present study identified high-risk zones, states, climatic regions and suitable sample type, diagnostic method for determining BT prevalence in India. Nearly one-third of sheep and goat populations are affected with BT in India. This warrants necessary control and preventive measures against BT by vaccination strategies, to uplift the small ruminant farming mostly managed by small and marginal farmers in India.