Climate change and sugarcane expansion increase Hantavirus infection risk

Hantavirus Cardiopulmonary Syndrome (HCPS) is a disease caused by Hantavirus, which is highly virulent for humans. High temperatures and conversion of native vegetation to agriculture, particularly sugarcane cultivation can alter abundance of rodent generalist species that serve as the principal reservoir host for HCPS, but our understanding of the compound effects of land use and climate on HCPS incidence remains limited, particularly in tropical regions. Here we rely on a Bayesian model to fill this research gap and to predict the effects of sugarcane expansion and expected changes in temperature on Hantavirus infection risk in the state of São Paulo, Brazil. The sugarcane expansion scenario was based on historical data between 2000 and 2010 combined with an agro-environment zoning guideline for the sugar and ethanol industry. Future evolution of temperature anomalies was derived using 32 general circulation models from scenarios RCP4.5 and RCP8.5 (Representative greenhouse gases Concentration Pathways adopted by IPCC). Currently, the state of São Paulo has an average Hantavirus risk of 1.3%, with 6% of the 645 municipalities of the state being classified as high risk (HCPS risk ≥ 5%). Our results indicate that sugarcane expansion alone will increase average HCPS risk to 1.5%, placing 20% more people at HCPS risk. Temperature anomalies alone increase HCPS risk even more (1.6% for RCP4.5 and 1.7%, for RCP8.5), and place 31% and 34% more people at risk. Combined sugarcane and temperature increases led to the same predictions as scenarios that only included temperature. Our results demonstrate that climate change effects are likely to be more severe than those from sugarcane expansion. Forecasting disease is critical for the timely and efficient planning of operational control programs that can address the expected effects of sugarcane expansion and climate change on HCPS infection risk. The predicted spatial location of HCPS infection risks obtained here can be used to prioritize management actions and develop educational campaigns.

汉坦病毒心肺综合征（Hantavirus Cardiopulmonary Syndrome, HCPS）是由汉坦病毒引发的高致病性人类疾病。高温事件以及原生植被向农业用地的转化（尤以甘蔗种植为甚），会改变作为HCPS主要储存宿主的啮齿类广食性物种的种群丰度，但目前学界对土地利用与气候的复合效应如何影响HCPS发病率的认知仍较为有限，在热带地区这一局限尤为突出。
本研究依托贝叶斯模型（Bayesian model）填补这一研究空白，对巴西圣保罗州内甘蔗扩张与气温预期变化对汉坦病毒感染风险的影响开展预测。
本研究中的甘蔗扩张情景基于2000至2010年的历史数据，并结合糖业与乙醇行业的农业环境分区指南制定；气温异常的未来演变则采用了政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）所采用的典型温室气体浓度路径（Representative Greenhouse Gases Concentration Pathways, RCP）RCP4.5与RCP8.5情景下的32个通用环流模型。
当前，圣保罗州的汉坦病毒平均感染风险为1.3%，该州645个市镇中有6%被划为高风险区域（HCPS感染风险≥5%）。
研究结果显示，仅甘蔗扩张一项即可将HCPS平均感染风险提升至1.5%，使受HCPS风险威胁的人口增加20%；仅考虑气温异常的情景下，HCPS感染风险的提升更为显著（RCP4.5情景下为1.6%，RCP8.5情景下为1.7%），受威胁人口分别增加31%与34%。甘蔗扩张与气温升高的复合情景所得到的预测结果，与仅纳入气温因素的情景完全一致。本研究结果表明，气候变化对HCPS感染风险的影响大概率比甘蔗扩张更为严峻。
疾病预测对于及时高效地规划防控实操方案至关重要，此类方案可应对甘蔗扩张与气候变化给HCPS感染风险带来的预期影响。
本研究得到的HCPS感染风险预测空间分布结果，可用于优先确定管理行动优先级并制定宣传教育活动方案。