Marianelli Cinzia, Verrubbi Vladimiro, Pruiti Ciarello Flavia, Ippolito Dorotea, Pacciarini Maria Lodovica, Di Marco Lo Presti Vincenzo
Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy.
Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, Rome, Italy.
Front Microbiol. 2023 Mar 17;14:1107396. doi: 10.3389/fmicb.2023.1107396. eCollection 2023.
The persistence of animal tuberculosis (TB) in livestock is a major concern in Sicily, Italy. The objective of this study was to elucidate the transmission dynamics of infection in a highly circumscribed, and at the same time geographically diverse, high-risk area of the island through an in-depth geo-epidemiological investigation of TB in cattle and black pigs raised in small-scale extensive farms across the district of Caronia.
We used genotype analysis coupled with geographic information system (GIS) technology and phylogenetic inference to characterize the spatial distribution of TB and genotypes in livestock and the genetic relationships between isolates. A total of 589 isolates collected from slaughtered cattle ( = 527) and Sicilian black pigs ( = 62) over a 5-year period (2014-2018) were included in the study.
TB was widespread throughout the district and was most frequent in the north-central area of the district, especially along one of the district's streams. We identified a total of 62 genotypes. Identical genetic profiles were isolated from both neighboring and non-neighburing herds. The 10 most frequent genotypes, accounting for 82% of isolates, showed geographic specificities in that they tended to cluster in specific spatial niches. The landscape structure of these niches-i.e. steep slopes, rocky ridges, meadows and streams-is likely to have had a significant influence on the distribution of TB among livestock in Caronia. Higher concentrations of TB were observed along streams and in open meadows, while rocky ridges and slopes appeared to have hampered the spread of TB.
The geographical distribution of TB cases among livestock in Caronia is consistent with several epidemiological scenarios (e.g., high density of infected herds along the streams or in hilly plateau where livestock share pastures). Landscape structure is likely to play an important role in the transmission and persistence of infection across the district. Additional potential risk factors, such as livestock trading and extensive breeding methods, are also discussed. Our results will contribute to the improvement of surveillance, control and eradication activities of TB in Sicily by the implementation of TB control measures, especially in farms located along streams, sharing common pastures or with mixed animal species.
动物结核病在意大利西西里岛家畜中的持续存在是一个主要问题。本研究的目的是通过对卡罗尼亚地区小规模粗放型农场饲养的牛和黑猪的结核病进行深入的地理流行病学调查，阐明该岛一个高度限定且同时地理分布多样的高风险地区的感染传播动态。
我们使用基因型分析结合地理信息系统（GIS）技术和系统发育推断来表征家畜中结核病和基因型的空间分布以及分离株之间的遗传关系。本研究纳入了在5年期间（2014 - 2018年）从屠宰牛（n = 527）和西西里黑猪（n = 62）收集的总共589株分离株。
结核病在整个地区广泛存在，在该地区的中北部最为常见，尤其是沿着该地区的一条溪流。我们总共鉴定出62种基因型。在相邻和不相邻的畜群中都分离出了相同的遗传图谱。10种最常见的基因型占分离株的82%，它们表现出地理特异性，倾向于聚集在特定的空间生态位中。这些生态位的景观结构——即陡坡、岩石山脊、草地和溪流——可能对卡罗尼亚家畜中结核病的分布产生了重大影响。在溪流沿岸和开阔草地上观察到更高的结核病浓度，而岩石山脊和斜坡似乎阻碍了结核病的传播。
卡罗尼亚家畜中结核病病例的地理分布与几种流行病学情况一致（例如，溪流沿岸或家畜共享牧场的丘陵高原地区感染畜群密度高）。景观结构可能在整个地区感染的传播和持续存在中发挥重要作用。还讨论了其他潜在风险因素，如家畜交易和粗放养殖方式。我们的结果将有助于通过实施结核病控制措施来改进西西里岛结核病的监测、控制和根除活动，特别是在沿溪流、共享共同牧场或有混合动物种类的农场。
