Department of Public Health, State University of Campinas, São Paulo, Brazil.
Superintence for Control of Endemic Diseases, State Secretariat of Health of São Paulo, Mogi Guaçu, Brazil.
Acta Trop. 2020 Jul;207:105496. doi: 10.1016/j.actatropica.2020.105496. Epub 2020 Apr 18.
Brazilian spotted fever (BSF) is a highly lethal disease in southeastern Brazil. BSF is caused by the bacterium Rickettsia rickettsii and is transmitted by the bites of the tick of the genus Amblyomma. The spatial distribution of BSF risk areas is not well known in the country given the complexity of the transmission cycle. This study used the ecological niche modeling (ENM) approach to anticipate the potential distribution of the etiological agent (Rickettsia rickettsii), vectors (Amblyomma sculptum and A. dubitatum), and hosts (Hydrochoerus hydrochaeris, Didelphis aurita, and D. marsupialis) of BSF in Brazil. We compiled occurrence records for all vectors, hosts, and BSF from our own field surveillance, online repositories, and literature. ENM identified BSF risk areas in southeastern and southern Brazil, and anticipated other dispersed suitable areas in the western, central, and northeastern coast regions of Brazil. Tick vectors and mammalian hosts were confined to these same areas; however, host species showed broader suitability in northern Brazil. All species ENMs performed significantly better than random expectations. We also tested the BSF prediction based on 253 additional independent cases identified in our surveillance; the model anticipated 251 out of 253 of these independent cases. Background similarity tests comparing the ENMs of R. rickettsii, tick vectors, and mammalian hosts were unable to reject null hypotheses of niche similarity. Finally, we observed close coincidence between independent BSF cases, and areas suitable for combinations of vectors and hosts, reflecting the ability of these model pairs to anticipate the distribution of BSF cases across Brazil.
巴西出血热（BSF）是巴西东南部一种高致死性疾病。BSF 由立克次体引起，由安氏革蜱属的蜱叮咬传播。由于传播周期复杂，BSF 风险地区的空间分布在该国并不为人所知。本研究使用生态位模型（ENM）方法预测巴西出血热的病因（立氏立克次体）、媒介（A. sculptum 和 A. dubitatum）和宿主（H. hydrochaeris、D. aurita 和 D. marsupialis）的潜在分布。我们从自己的实地监测、在线存储库和文献中整理了所有媒介、宿主和 BSF 的发生记录。ENM 确定了巴西东南部和南部的 BSF 风险区，并预测了巴西西部、中部和东北部沿海地区其他分散的适宜区。蜱媒介和哺乳动物宿主都局限于这些相同的地区；然而，宿主物种在巴西北部表现出更广泛的适宜性。所有物种的 ENM 表现明显优于随机预期。我们还根据我们的监测中确定的 253 个额外独立病例测试了 BSF 预测；该模型预测了 253 个独立病例中的 251 个。比较立氏立克次体、蜱媒介和哺乳动物宿主的 ENM 的背景相似性测试无法拒绝生态位相似性的零假设。最后，我们观察到独立 BSF 病例与适合媒介和宿主组合的区域非常吻合，这反映了这些模型对预测巴西各地 BSF 病例分布的能力。
