Mapping the global potential transmission hotspots for severe fever with thrombocytopenia syndrome by machine learning methods

Abstract

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with increasing spread. Currently SFTS transmission has expanded beyond Asian countries, however, with definitive global extents and risk patterns remained obscure. Here we established an exhaustive database that included globally reported locations of human SFTS cases and the competent vector, Haemaphysalis longicornis (H. longicornis), as well as the explanatory environmental variables, based on which, the potential geographic range of H. longicornis and risk areas for SFTS were mapped by applying two machine learning methods. Ten predictors were identified contributing to global distribution for H. longicornis with relative contribution ≥1%. Outside contemporary known distribution, we predict high receptivity to H. longicornis across two continents, including northeastern USA, New Zealand, parts of Australia, and several Pacific islands. Eight key drivers of SFTS cases occurrence were identified, including elevation, predicted probability of H. longicornis presence, two temperature-related factors, two precipitation-related factors, the richness of mammals and percentage coverage of water bodies. The globally model-predicted risk map of human SFTS occurrence was created and validated effective for discriminating the actual affected and unaffected areas (median predictive probability 0.74 vs. 0.04, P < 0.001) in three countries with reported cases outside China. The high-risk areas (probability ≥50%) were predicted mainly in east-central China, most parts of the Korean peninsula and southern Japan, and northern New Zealand. Our findings highlight areas where an intensive vigilance for potential SFTS spread or invasion events should be advocated, owing to their high receptibility to H. longicornis distribution.

Comparison of Habitat Suitability Models for Haemaphysalis longicornis Neumann in North America to Determine Its Potential Geographic Range

“…The most noted human pathogen transmitted by the H. longicornis in its native range in East Asia is the SFTSV [4]. Since its discovery in 2009, cases of SFTSV have been increasingly reported in East Asia [46]. In November 2019, the first case of SFTSV was reported from Taiwan [47], and cases have also occurred in Vietnam [48], suggesting that the SFTSV is expanding its range in Asia.…”

Time Course of Severe Fever With Thrombocytopenia Syndrome Virus and Antibodies in Patients by Long-Term Follow-Up Study, China

“…Anhui province has shown a higher disease burden of SFTS ( Zhan et al, 2017 ; Bopp et al, 2020 ; Li et al, 2021 ). Besides China, SFTSV infections have also been confirmed in Japan, South Korea, Vietnam, and Pakistan ( Li, 2015 ; Tran et al, 2019 ; Bopp et al, 2020 ; Miao et al, 2020 ). The virus was not only transmitted by tick bites but although by person-to-person transmission ( Gong et al, 2018 ; Jung et al, 2019 ).…”

Estimating severe fever with thrombocytopenia syndrome transmission using machine learning methods in South Korea

“…The risk factors of SFTS cases in China have been analyzed using univariate analysis of epidemiological data 11 , 13 . Moreover, previous studies have estimated the occurrence of SFTS by assessing risk factors 10 , 12 , 14 . The risk of demographic and spatiotemporal features of SFTS occurrence in Shandong Province has been estimated using the maximum entropy niche model 14 .…”