Seroprevalence study of peste des petits ruminants in sheep and goats in the northern region of India

Abstract

Background and Aim: Peste des petits ruminants (PPR) is a contagious, World Organization for Animal Health notifiable, economically important, transboundary morbilliviral disease of sheep and goats. Studying seroprevalence of PPR from different geographical areas under varying agro-climatic conditions may help in formulating effective and appropriate disease control strategies under the ongoing national PPR control program. The present cross-sectional study describes the prevalence of PPR virus antibodies in sheep and goats in the various epidemiological units in different states (Haryana, Himachal Pradesh [HP], Jammu and Kashmir [J&K], Punjab, Uttarakhand [UK], and Uttar Pradesh [UP]) of the northern region of India. Materials and Methods: A total of 5843 serum samples (sheep [n=2463] and goats [n=3380]) were collected by stratified random sampling method from 322 epidemiological units in the studied region during 2017-2018 and tested for PPR virus (PPRV) antibodies by competitive ELISA. Results: The results revealed that an overall seroprevalence of 44.05% (2574/5843) with 57.32%, 55.22%, 65.69%, 37.09%, 32.73%, and 29.35% prevalence of PPRV antibodies in small ruminants in Haryana, Punjab, UP, HP, J&K, and UK states, respectively. Further, Chi-squared test revealed an association of PPRV antibodies in goats (χ2=252.28, p<0.01) and sheep (χ2=192.12, p<0.01) across different states in the region. Conclusion: The seroprevalence in majority of the epidemiological units (n=130) in sheep and goats in the studied region had <30%. This necessitates comprehensive, rigorous, continuous vaccination and active surveillance programs for few more years to achieve the desired 70% seroprevalence level of PPRV antibodies in population and to make the northern region of India, as PPR free zone.

Temporal and Spatial Epidemiological Analysis of Peste Des Petits Ruminants Outbreaks from the Past 25 Years in Sheep and Goats and Its Control in India

“…Further, the number of reported outbreaks and cases showed a declining trend from 2005, which might be due to the implementation of focussed vaccination in some states since 2002 [ 11 ], and the strategic vaccination under PPR-CP in a few states from 2011, besides implementation of the biosecurity measures to prevent the spread and control of PPR outbreaks. However, during 2018–2019, the marginal increase in the number of outbreaks only in some defined geographical areas in Maharashtra, Haryana, Jharkhand, and West Bengal when compared to 2017 ( Figure 6 ), might be due to the migration/movements of the non-vaccinated animals for grazing/trade as well as non-implementation of the vaccination as per the direction of the strategic vaccination under PPR-CP [ 18 , 19 , 20 ]. Further, the multivariable regression analysis of outbreaks revealed disease occurrence in the East zone was positively associated and significant, as in this zone more outbreaks were being reported than other zones, as extensive vaccination is not being practiced.…”

“…The variation in disease endemicity might be due to differences in animal husbandry practices and the agro-climatic conditions affecting the pattern of the natural vegetation which indirectly influences the socio-economic factors, the migration patterns of small ruminants, flock size, and the population density of the animals in the different states. Although India is endemic to PPR, north-eastern states either free from disease or have very few reports [ 12 , 21 , 44 ]. North-East states have a relatively small sheep and goats population and intermixing of these animals with the small ruminants population from the rest of the country is usually limited because of very narrow connecting passage [ 12 , 21 , 44 ].…”

“…Although India is endemic to PPR, north-eastern states either free from disease or have very few reports [ 12 , 21 , 44 ]. North-East states have a relatively small sheep and goats population and intermixing of these animals with the small ruminants population from the rest of the country is usually limited because of very narrow connecting passage [ 12 , 21 , 44 ]. Further, the hilly terrain characterizing this region may restrict the movement of animals and disease transmission [ 45 ].…”

“…Since 2002, focused vaccination and/or strategic vaccination under PPR-CP were carried out in some states but neither systematic sero-monitoring was initiated during the last decade to assess the efficacy of the vaccination program nor any sero-surveillance plan was undertaken during these periods [ 29 ]. A national-wide serosurvey in sheep and goats during 2017–2018 by PPR competitive ELISA [ 17 ] showed wide variations of PPR seroprevalence/immune population in the different states in India [ 18 , 19 , 20 , 21 ]. The immune populations were greater in regular vaccination practiced states (Andhra Pradesh, Telangana, Karnataka, Chhattisgarh, Maharashtra, Gujarat, Punjab, Haryana) compared with focused or non-vaccinated states (Kerala, Tamil Nadu, Bihar, Assam, Goa, Himachal Pradesh, Jammu and Kashmir, Madhya Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Odisha, Tripura, Uttara Pradesh, Uttarakhand, West Bengal), where the disease is endemic and outbreaks are being regularly reported.…”

“…In India, several outbreaks of PPR in sheep and goats have not been recorded properly, owing to inadequate animal disease surveillance and reporting systems [ 15 , 16 ]. Further, a national-wide serosurvey conducted by employing the PPR competitive ELISA [ 17 ] in sheep and goats during 2017–2018 showed a wide variation in the prevalence status of PPRV antibodies (seroprevalence/immune population) in the different states of India as vaccination strategies employed and coverage by the states varied significantly [ 18 , 19 , 20 , 21 ], even though it is not possible to distinguish the vaccinated and infected animals, as the differentiation of infected from vaccinated animals (DIVA) vaccine was not being used in the PPR-CP.…”