To investigate the spread of Rice yellow mottle virus (RYMV) along the Niger River, regular sampling of virus isolates was conducted along 500 km of the Niger Valley in the Republic of Niger and was complemented by additional sampling in neighbouring countries in West Africa and Central Africa. The spread of RYMV into and within the Republic of Niger was inferred as a continuous process using a Bayesian statistical framework applied previously to reconstruct its dispersal history in West Africa, East Africa, and Madagascar. The spatial resolution along this section of the Niger River was the highest implemented for RYMV and possibly for any plant virus. We benefited from the results of early field surveys of the disease for the validation of the phylogeographic reconstruction and from the well-documented history of rice cultivation changes along the Niger River for their interpretation. As a prerequisite, the temporal signal of the RYMV data sets was revisited in the light of recent methodological advances. The role of the hydrographic network of the Niger Basin in RYMV spread was examined, and the link between virus population dynamics and the extent of irrigated rice was assessed. RYMV was introduced along the Niger River in the Republic of Niger in the early 1980s from areas to the southwest of the country where rice was increasingly grown. Viral spread was triggered by a major irrigation scheme made of a set of rice perimeters along the river valley. The subsequent spatial and temporal host continuity and the inoculum build-up allowed for a rapid spread of RYMV along the Niger River, upstream and downstream, over hundreds of kilometres, and led to the development of severe epidemics. There was no evidence of long-distance dissemination of the virus through natural water. Floating rice in the main meanders of the Middle Niger did not contribute to virus dispersal from West Africa to Central Africa. RYMV along the Niger River is an insightful example of how agricultural intensification favours pathogen emergence and spread.

中文翻译：

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尼日尔河谷植物病毒、水稻黄斑驳病毒的河流和景观生态学

为了调查水稻黄斑驳病毒 (RYMV) 沿尼日尔河的传播情况，在尼日尔共和国尼日尔河谷 500 公里的范围内对病毒分离株进行了定期采样，并在西非和中部的邻国进行了补充采样非洲。RYMV 传播到尼日尔共和国和在尼日尔共和国内部被推断为一个连续的过程，使用以前应用的贝叶斯统计框架来重建其在西非、东非和马达加斯加的传播历史。尼日尔河这一段的空间分辨率是 RYMV 实施的最高的，可能是任何植物病毒的。我们受益于该疾病的早期实地调查结果，以验证系统地理学重建，并受益于尼日尔河沿岸水稻种植变化的有据可查的历史，以供解释。作为先决条件，根据最近的方法学进展重新审视了 RYMV 数据集的时间信号。研究了尼日尔盆地水文网络在 RYMV 传播中的作用，并评估了病毒种群动态与水稻灌溉范围之间的联系。RYMV 于 1980 年代初从尼日尔共和国西南部的水稻种植日益增多的地区沿尼日尔河引入。病毒传播是由沿河谷的一组水稻周边组成的大型灌溉计划引发的。随后宿主在空间和时间上的连续性和接种物的积累使得 RYMV 沿着尼日尔河上游和下游迅速传播，传播范围超过数百公里，并导致严重流行病的发展。没有证据表明病毒可以通过天然水进行远距离传播。尼日尔中部主要河道的漂浮水稻对病毒从西非向中非的传播没有帮助。尼日尔河沿岸的 RYMV 是农业集约化如何有利于病原体出现和传播的一个富有洞察力的例子。没有证据表明病毒可以通过天然水进行远距离传播。尼日尔中部主要河道的漂浮水稻对病毒从西非向中非的传播没有帮助。尼日尔河沿岸的 RYMV 是农业集约化如何有利于病原体出现和传播的一个富有洞察力的例子。没有证据表明病毒可以通过天然水进行远距离传播。尼日尔中部主要河道的漂浮水稻对病毒从西非向中非的传播没有帮助。尼日尔河沿岸的 RYMV 是农业集约化如何有利于病原体出现和传播的一个富有洞察力的例子。