Ashango Asrat Arke, Waktole Hika, Leta Samson, Negussie Haileleul
Department of Veterinary Epidemiology and Public Health, College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Ethiopia.
Department of Veterinary Microbiology, Parasitology and Poultry Health, College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Ethiopia.
Transbound Emerg Dis. 2025 Jul 13;2025:6620243. doi: 10.1155/tbed/6620243. eCollection 2025.
Livestock trade significantly contributes to the spread of transboundary animal diseases (TADs), like Peste des Petits Ruminants virus (PPRV), due to the long-distance movement of infected animals. This study investigates the structure and dynamics of the small ruminant trade network across 64 markets and 20 destinations, focusing on market connectivity, trade patterns, and disease risk. Eight key markets were identified due to their significant trading activity and connections. During the study period, 365,261 small ruminants were traded, with 54% directed toward market destinations and the remainder to slaughterhouses or cross-border locations, primarily Somaliland and Kenya. Over 85% of transport to these destinations was by truck, while more than 55% of internal movements were on foot. Trade peaked between July and September, accounting for 42% of the annual trade volume and 46% of cross-border movements. Network analysis revealed 172 distinct trade routes with varying activity levels: 12 persistent, 47 frequent, 42 intermediate, and 69 occasional. The network exhibited low connectivity (density = 0.024) and low reciprocity (0.104), with a negative assortativity (-0.52), indicating smaller markets often connected with larger ones. The network's clustering coefficient was 0.729, and the average path length was 2.216, contrasting with simulated random networks that had a clustering coefficient of 0.047 and an average path length of 3.22. Key markets were identified as "gate-keepers" and "pulse takers," facilitating connections between isolated and central markets. The epidemic threshold (q) and R0 indicated a high risk of disease spread, especially from July to October. The study found that removing key markets drastically reduced network cohesion, with a 10% removal of central nodes decreasing the giant strongly connected component (GSCC) size by ~80%. Peste des Petits Ruminants (PPR) outbreaks in 2023 correlated strongly with market centrality, highlighting the need for targeted monitoring and control measures. This study underscores the importance of understanding network dynamics to manage trade efficiently and mitigate disease risks in small ruminant populations.
由于感染动物的长途运输，牲畜贸易对跨界动物疾病（TADs）的传播有重大影响，如小反刍兽疫病毒（PPRV）。本研究调查了64个市场和20个目的地的小反刍兽贸易网络的结构和动态，重点关注市场连通性、贸易模式和疾病风险。由于其重要的贸易活动和联系，确定了八个关键市场。在研究期间，共交易了365,261只小反刍兽，其中54%运往市场目的地，其余运往屠宰场或跨境地点，主要是索马里兰和肯尼亚。运往这些目的地的运输中，超过85%是通过卡车，而国内运输中超过55%是步行。贸易在7月至9月达到顶峰，占年贸易量的42%和跨境运输量的46%。网络分析揭示了172条不同活动水平的贸易路线：12条持续路线、47条频繁路线、42条中间路线和69条偶尔路线。该网络显示出低连通性（密度 = 0.024）和低互惠性（0.104），具有负向聚类系数（-0.52），表明较小的市场通常与较大的市场相连。该网络的聚类系数为0.729，平均路径长度为2.216，与聚类系数为0.047、平均路径长度为3.22的模拟随机网络形成对比。关键市场被确定为“守门人”和“脉搏采集者”，促进了孤立市场和中心市场之间的联系。流行阈值（q）和R0表明疾病传播风险很高，特别是在7月至10月。研究发现，移除关键市场会大幅降低网络凝聚力，移除10% 的中心节点会使巨型强连通分量（GSCC）大小减少约80%。2023年的小反刍兽疫（PPR）疫情与市场中心性密切相关，凸显了针对性监测和控制措施的必要性。本研究强调了理解网络动态对于有效管理贸易和减轻小反刍兽种群疾病风险的重要性。
