Molini Umberto, Coetzee Lauren M, Hemberger Maria Y, Chiwome Bernard, Khaiseb Siegfried, Dundon William G, Franzo Giovanni
School of Veterinary Medicine, Faculty of Health Sciences and Veterinary Medicine, University of Namibia, Windhoek, Namibia.
Central Veterinary Laboratory (CVL), Windhoek, Namibia.
Front Vet Sci. 2024 Jan 15;10:1323974. doi: 10.3389/fvets.2023.1323974. eCollection 2023.
The swine sector in Africa plays an important role in local economies, contributing to poverty alleviation and community subsistence. In addition, intensive farming is progressively becoming more important in the region. Therefore, any disease affecting swine populations can have detrimental effects on local communities. Porcine Reproductive and Respiratory Syndrome (PRRS) is among the most important infectious diseases affecting swine worldwide, but information on its epidemiology in Africa is extremely limited.
In the present study, 147 healthy butchered pigs, originating from 15 Namibian intensive and rural farms were tested by RT-PCR and the ORF7 genes of positive samples were sequenced for further genetic characterization and phylogenetic analysis. Additionally, 55 warthogs were also evaluated using the same approach.
Overall, 7 out of 147 pigs (4.76%) tested positive, all originating from 3 rural farms (with a within-herd detection frequency higher than 14%) characterized by strong epidemiological links. All industrial pig and warthog samples were negative. Sequence analysis revealed that all strains belonged to the species, previously known as PRRSV type I, and were likely imported from Europe at least 6 years ago, evolving independently thereafter. When and how the first introduction occurred could not be determined due to the absence of other African sequences for comparison.
The present work provides the first detection and characterization of PRRSV molecular epidemiology in Namibia. Based on the present findings, the presence of the PPRSV appears marginal and limited to backyard farms. While biosecurity measures applied in industrial farms appear to be effective in preventing viral introduction, PRRSV circulation in rural settings still represents a potential threat, and considering the socio-economical implication of livestock diseases decreasing animal performances in rural areas, active monitoring should be encouraged to promptly act against emerging menaces and guarantee the welfare of local pig populations.
非洲的养猪业在当地经济中发挥着重要作用，有助于减轻贫困和维持社区生计。此外，集约化养殖在该地区正变得越来越重要。因此，任何影响猪群的疾病都可能对当地社区产生不利影响。猪繁殖与呼吸综合征（PRRS）是全球影响猪的最重要传染病之一，但关于其在非洲的流行病学信息极为有限。
在本研究中，对来自纳米比亚15个集约化和农村农场的147头健康屠宰猪进行了逆转录聚合酶链反应（RT-PCR）检测，并对阳性样本的开放阅读框7（ORF7）基因进行测序，以进行进一步的基因特征分析和系统发育分析。此外，还使用相同方法对55头疣猪进行了评估。
总体而言，147头猪中有7头（4.76%）检测呈阳性，均来自3个农村农场（群体内检测频率高于14%），这些农场具有很强的流行病学联系。所有工业猪场的猪和疣猪样本均为阴性。序列分析表明，所有毒株均属于以前称为I型PRRSV的物种，可能至少在6年前从欧洲传入，此后独立进化。由于缺乏其他非洲序列进行比较，无法确定首次传入的时间和方式。
本研究首次对纳米比亚PRRSV的分子流行病学进行了检测和特征分析根据目前的研究结果，PRRSV的存在似乎很有限，仅限于后院农场。虽然工业农场实施的生物安全措施似乎能有效防止病毒传入，但PRRSV在农村地区的传播仍然是一个潜在威胁，考虑到牲畜疾病对社会经济的影响以及农村地区动物生产性能的下降，应鼓励进行积极监测，以便及时应对新出现的威胁，保障当地猪群的健康。
