Prevalence of Eimeria species in sheep of arid and semi-arid Rajasthan

Abstract

With the aim to devise suitable preventive strategy, an assessment on the diversity and seasonal occurrence of coccidia was carried out in farm and field flocks of sheep in Rajasthan. From April 2004 to March 2019, a total of 139428 faecal samples were examined for Eimeria spp. infection and to determine composition of prevalent species at monthly intervals. The data were analyzed to observe the effect of different geographical regions, management practices, seasons and months on the prevalence of Eimeria infection. Flock-wise it varied from 27.0% (arid farm and semi-arid field) to 33.8% (semi-arid farm). Within the agroclimatic regions, management of flocks had significant (P<0.001) effect with higher prevalence of Eimeria spp. in the farm as compared to the field flocks in the semi-arid region while reverse trend was observed in the arid region. Effects of year, season and month had significant (P<0.001) effect on the prevalence of Eimeria infection in all categories of sheep flocks in Rajasthan. On comparison between farm and field flocks (irrespective of the agroclimatic region), a non-consistent pattern was observed for annual prevalence of Eimeria infection. The overall seasonal prevalence varied significantly (P<0.001) from 25.1 (winter) to 31.8% (monsoon) in farm flocks and from 24.4 (winter) to 33.3% (monsoon) in field flocks. As per flock management, the overall monthly prevalence varied significantly (P<0.001) from 21.7 (January) to 33.6% (July) in farm and from 22.7 (March) to 37.6% (July) in the field. In general, the prevalence of Eimeria infection among flocks started rising with increase in environmental temperature in April probably due to stress on animals and reached to peak in July/August due to prevalent hot-humid conditions. The overall composition of Eimeria species showed higher proportion of E. parva (44.2–45.1%) and E. pallida (27.3–29.2%). The other species prevalent were E. faurei (11.8–12.6%), E. ovinoidalis (4.3–5.0%), E. intricata (2.9–6.3%), E. granulosa (4.2–5.0%) and E. ahsata (0.4–1.1%). For majority of the species, effect of season and month was non-significant in both the agroclimatic regions. The study suggested that moderate level of infection with Eimeria spp. in adult sheep persisted throughout the year with higher prevalence during monsoon. Adult animals with moderate infection contaminate the environment and are the main source of infection for lambs, particularly in the lambing period.