Sevá Anaiá da Paixão, Mao Liang, Galvis-Ovallos Fredy, Tucker Lima Joanna Marie, Valle Denis
Department of Mathematics, University of Florida, Gainesville, Florida, United States of America.
Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Sciences, University of São Paulo, São Paulo, Brazil.
PLoS Negl Trop Dis. 2017 Feb 6;11(2):e0005353. doi: 10.1371/journal.pntd.0005353. eCollection 2017 Feb.
Visceral leishmaniasis (VL) is an important neglected disease caused by a protozoan parasite, and represents a serious public health problem in many parts of the world. It is zoonotic in Europe and Latin America, where infected dogs constitute the main domestic reservoir for the parasite and play a key role in VL transmission to humans. In Brazil this disease is caused by the protozoan Leishmania infantum chagasi, and is transmitted by the sand fly Lutzomyia longipalpis. Despite programs aimed at eliminating infection sources, the disease continues to spread throughout the Country. VL in São Paulo State, Brazil, first appeared in the northwestern region, spreading in a southeasterly direction over time. We integrate data on the VL vector, infected dogs and infected human dispersion from 1999 to 2013 through an innovative spatial temporal Bayesian model in conjunction with geographic information system. This model is used to infer the drivers of the invasion process and predict the future progression of VL through the State. We found that vector dispersion was influenced by vector presence in nearby municipalities at the previous time step, proximity to the Bolívia-Brazil gas pipeline, and high temperatures (i.e., annual average between 20 and 23°C). Key factors affecting infected dog dispersion included proximity to the Marechal Rondon Highway, high temperatures, and presence of the competent vector within the same municipality. Finally, vector presence, presence of infected dogs, and rainfall (approx. 270 to 540mm/year) drove the dispersion of human VL cases. Surprisingly, economic factors exhibited no noticeable influence on disease dispersion. Based on these drivers and stochastic simulations, we identified which municipalities are most likely to be invaded by vectors and infected hosts in the future. Prioritizing prevention and control strategies within the identified municipalities may help halt the spread of VL while reducing monitoring costs. Our results contribute important knowledge to public and animal health policy planning, and suggest that prevention and control strategies should focus on vector control and on blocking contact between vectors and hosts in the priority areas identified to be at risk.
内脏利什曼病（VL）是一种由原生动物寄生虫引起的重要被忽视疾病，在世界许多地区都是严重的公共卫生问题。在欧洲和拉丁美洲，它是人畜共患病，受感染的狗是该寄生虫的主要家养宿主，在VL传播给人类的过程中起关键作用。在巴西，这种疾病由原生动物婴儿利什曼原虫恰加斯亚种引起，通过长须罗蛉传播。尽管有旨在消除感染源的项目，但该疾病仍在巴西全国蔓延。巴西圣保罗州的VL最初出现在西北部地区，随着时间的推移向东南方向扩散。我们通过一个创新的时空贝叶斯模型结合地理信息系统，整合了1999年至2013年期间VL媒介、受感染狗和受感染人类分布的数据。该模型用于推断入侵过程的驱动因素，并预测VL在该州未来的发展。我们发现，媒介分布受到前一时间步附近城市中媒介的存在、靠近玻利维亚 - 巴西天然气管道以及高温（即年平均温度在20至23°C之间）的影响。影响受感染狗分布的关键因素包括靠近马雷夏尔·朗东高速公路、高温以及同一城市内存在合适的媒介。最后，媒介的存在、受感染狗的存在以及降雨（约270至540毫米/年）推动了人类VL病例的分布。令人惊讶的是，经济因素对疾病分布没有明显影响。基于这些驱动因素和随机模拟，我们确定了哪些城市未来最有可能被媒介和受感染宿主入侵。在确定的城市中优先实施预防和控制策略可能有助于阻止VL的传播，同时降低监测成本。我们的结果为公共和动物卫生政策规划贡献了重要知识，并表明预防和控制策略应侧重于媒介控制以及在确定为有风险的优先区域阻断媒介与宿主之间的接触。
