Gurrappanaidu Govindaraj, Subbanna Naveen Kumar Gajalavarahalli, Wanyoike Francis, Bahta Sirak, Reddy Yeswanth Raghuram, Bardhan Dwaipayan, Vinayagamurthy Balamurugan, Vijayalakshmy Kennady, Habibur Rahman
ICAR-National Institute of Veterinary Epidemiology and Disease Informatics, Post Box 6450, Yelahanka, Bengaluru 560064, India.
International Livestock Research Institute (ILRI), Post Box 30709, Nairobi 00100, Kenya.
Viruses. 2024 Dec 27;17(1):23. doi: 10.3390/v17010023.
Mass vaccination against peste des petits ruminants (PPR) in two southern states of India, namely Andhra Pradesh and Karnataka, has reduced disease outbreaks significantly. The sporadic outbreaks reported now can be attributed in part to the recurring movement of sheep and goats between these contiguous states. This study assessed the present level of economic burden and impact of vaccination on the local system (one state), considering the exposure from the external system (neighboring state) using a system dynamic (SD) model. The SD model relies on interdependence, interaction, information feedback, and circular causality and captures potential feedback between disease control interventions and their impact on various epidemiological and economic outcomes. The data for parameterization of the model were collected through surveys, expert elicitation, and literature review. The sporadic outbreaks reported in recent years (<10 outbreaks/year during 2022) were due to continuous "mass vaccination" for more than a decade. During 2021-2022, the PPR incidence was less in both the states, with an estimated loss of USD 26.30 and USD 22.86 million in Andhra Pradesh and Karnataka, respectively. The SD model results showed a systemic increase in flock size and offtakes and a decline in the number of infected and death cases under high vaccination coverage (75% and 100% coverage) compared to the low-coverage scenario. Hence, the coordinated inter-state vaccination efforts offer better prospects, as efforts in one state have positive externalities in terms of fewer outbreaks in a neighboring state.
在印度南部的两个邦，即安得拉邦和卡纳塔克邦，针对小反刍兽疫（PPR）进行大规模疫苗接种，已显著减少了疾病暴发。现在报告的零星疫情部分可归因于绵羊和山羊在这两个接壤邦之间的反复流动。本研究使用系统动力学（SD）模型，评估了当前的经济负担水平以及疫苗接种对本地系统（一个邦）的影响，同时考虑了来自外部系统（邻邦）的暴露情况。SD模型依赖于相互依存、相互作用、信息反馈和循环因果关系，并捕捉疾病控制干预措施及其对各种流行病学和经济结果的影响之间的潜在反馈。通过调查、专家意见征集和文献综述收集了用于模型参数化的数据。近年来报告的零星疫情（2022年期间每年<10起疫情）是由于十多年来持续进行“大规模疫苗接种”。在2021 - 2022年期间，两个邦的PPR发病率都较低，安得拉邦和卡纳塔克邦估计损失分别为2630万美元和2286万美元。SD模型结果显示，与低接种覆盖率情景相比，在高疫苗接种覆盖率（75%和100%覆盖率）下，畜群规模和出栏量会系统性增加，感染和死亡病例数量会下降。因此，跨邦协调的疫苗接种努力前景更好，因为一个邦的努力在邻邦疫情减少方面具有正外部性。
