{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T18:40:11Z","timestamp":1788374411634,"version":"build-2803163510"},"reference-count":52,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2019,12,2]],"date-time":"2019-12-02T00:00:00Z","timestamp":1575244800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["41601368"],"award-info":[{"award-number":["41601368"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2016YFB0501505"],"award-info":[{"award-number":["2016YFB0501505"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Being a globally emerging mite-borne zoonotic disease, scrub typhus is a serious public health concern in Nepal. Mapping environmental suitability and quantifying the human population under risk of the disease is important for prevention and control efforts. In this study, we model and map the environmental suitability of scrub typhus using the ecological niche approach, machine learning modeling techniques, and report locations of scrub typhus along with several climatic, topographic, Normalized Difference Vegetation Index (NDVI), and proximity explanatory variables and estimated population under the risk of disease at a national level. Both MaxEnt and RF technique results reveal robust predictive power with test The area under curve (AUC) and true skill statistics (TSS) of above 0.8 and 0.6, respectively. Spatial prediction reveals that environmentally suitable areas of scrub typhus are widely distributed across the country particularly in the low-land Tarai and less elevated river valleys. We found that areas close to agricultural land with gentle slopes have higher suitability of scrub typhus occurrence. Despite several speculations on the association between scrub typhus and proximity to earthquake epicenters, we did not find a significant role of proximity to earthquake epicenters in the distribution of scrub typhus in Nepal. About 43% of the population living in highly suitable areas for scrub typhus are at higher risk of infection, followed by 29% living in suitable areas of moderate-risk, and about 22% living in moderately suitable areas of lower risk. These findings could be useful in selecting priority areas for surveillance and control strategies effectively.<\/jats:p>","DOI":"10.3390\/ijerph16234845","type":"journal-article","created":{"date-parts":[[2019,12,3]],"date-time":"2019-12-03T04:58:39Z","timestamp":1575349119000},"page":"4845","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":34,"title":["Mapping Environmental Suitability of Scrub Typhus in Nepal Using MaxEnt and Random Forest Models"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3824-5973","authenticated-orcid":false,"given":"Bipin","family":"Acharya","sequence":"first","affiliation":[{"name":"Department of Epidemiology, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0303-3978","authenticated-orcid":false,"given":"Wei","family":"Chen","sequence":"additional","affiliation":[{"name":"Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zengliang","family":"Ruan","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gobind","family":"Pant","sequence":"additional","affiliation":[{"name":"Department of Public Health, Manmohan Memorial Institute of Health Sciences, Kathmandu 44613, Nepal"},{"name":"Center for Environmental and Occupational Health in Nepal (CEOHN), Karnali Academy of Health Sciences (KAHS), Mahalaxmisthan, Lalitpur 44511, Nepal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yin","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2542-5377","authenticated-orcid":false,"given":"Lalan","family":"Shah","sequence":"additional","affiliation":[{"name":"Department of Health Services, Teku, Kathmandu 44600, Nepal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunxiang","family":"Cao","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7903-2141","authenticated-orcid":false,"given":"Zhiwei","family":"Xu","sequence":"additional","affiliation":[{"name":"School of Public Health, Faculty of Medicine, the University of Queensland, Herston, QLD 4006, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7176-7821","authenticated-orcid":false,"given":"Meghnath","family":"Dhimal","sequence":"additional","affiliation":[{"name":"Nepal Health Research Council, Kathmandu 44600, Nepal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hualiang","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,12,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Knoop, F.C. (2007). Scrub typhus. xPharm: The Comprehensive Pharmacology Reference, Elsevier.","DOI":"10.1016\/B978-008055232-3.60902-X"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"563","DOI":"10.3126\/nje.v6i2.15162","article-title":"Scrub typhus in Nepal","volume":"6","author":"Nayak","year":"2016","journal-title":"Nepal J. Epidemiol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Xu, G., Walker, D.H., Jupiter, D., Melby, P.C., and Arcari, C.M. (2017). A review of the global epidemiology of scrub typhus. PLoS Negl. Trop. Dis., 11.","DOI":"10.1371\/journal.pntd.0006062"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"S203","DOI":"10.1086\/596576","article-title":"Scrub typhus: The geographic distribution of phenotypic and genotypic variants of Orientia tsutsugamushi","volume":"48","author":"Kelly","year":"2009","journal-title":"Clin. Infect. Dis."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Luce-Fedrow, A., Lehman, M., Kelly, D., Mullins, K., Maina, A., Stewart, R., Ge, H., John, H., Jiang, J., and Richards, A. (2018). A review of scrub typhus (Orientia tsutsugamushi and related organisms): Then, now, and tomorrow. Trop. Med. Infect. Dis., 3.","DOI":"10.3390\/tropicalmed3010008"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"76","DOI":"10.4103\/0971-5916.193292","article-title":"Epidemiology & risk factors of scrub typhus in south India","volume":"144","author":"Varghese","year":"2016","journal-title":"Indian J. Med. Res."},{"key":"ref_7","unstructured":"Karki, K.B., Acharya, B.P., Dhimal, M., Aryal, K.K., Sharma, G.N., Khanal, P., Ranabhat, K., Dumre, S.P., and Jha, A.K. (2017). Descriptive Epidemiology of Scrub Typhus in Nepal, 2017."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1093\/jmedent\/11.3.237","article-title":"Review article: The ecology of chigger-borne Rickettsiosis (scrub typhus)1, 2","volume":"11","author":"Traub","year":"1974","journal-title":"J. Med. Entomol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1205","DOI":"10.1093\/cid\/ciy1050","article-title":"Spatiotemporal patterns and risk factors for scrub typhus from 2007 to 2017 in Southern China","volume":"69","author":"Zheng","year":"2019","journal-title":"Clin. Infect. Dis."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Wei, Y., Huang, Y., Li, X., Ma, Y., Tao, X., Wu, X., and Yang, Z. (2017). Climate variability, animal reservoir and transmission of scrub typhus in Southern China. PLoS Negl. Trop. Dis., 11.","DOI":"10.1371\/journal.pntd.0005447"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"229","DOI":"10.4081\/gh.2013.69","article-title":"Bayesian spatial modelling and the significance of agricultural land use to scrub typhus infection in Taiwan","volume":"8","author":"Wardrop","year":"2013","journal-title":"Geospat. Health"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Tsai, P.-J., and Yeh, H.-C. (2013). Scrub typhus islands in the Taiwan area and the association between scrub typhus disease and forest land use and farmer population density: Geographically weighted regression. BMC Infect. Dis., 13.","DOI":"10.1186\/1471-2334-13-191"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"755","DOI":"10.1111\/zph.12489","article-title":"Ecosystem change and zoonoses in the Anthropocene","volume":"65","author":"McMahon","year":"2018","journal-title":"Zoonoses Public Health"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.actatropica.2011.05.018","article-title":"Spatial analysis of scrub typhus infection and its association with environmental and socioeconomic factors in Taiwan","volume":"120","author":"Kuo","year":"2011","journal-title":"Acta Trop."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Min, K.D., Lee, J.Y., So, Y., and Cho, S.I. (2019). Deforestation increases the risk of scrub typhus in Korea. Int. J. Environ. Res. Public. Health, 16.","DOI":"10.3390\/ijerph16091518"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3389\/fmicb.2016.01174","article-title":"Advances and limitations of disease biogeography using ecological niche modeling","volume":"7","author":"Escobar","year":"2016","journal-title":"Front. Microbiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1614","DOI":"10.1098\/rstb.2012.0250","article-title":"Global mapping of infectious disease","volume":"368","author":"Hay","year":"2013","journal-title":"Philos. Trans. R. Soc. B Biol. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"328","DOI":"10.1016\/j.tree.2005.03.009","article-title":"Spatial epidemiology: An emerging (or re-emerging) discipline","volume":"20","author":"Ostfeld","year":"2005","journal-title":"Trends Ecol. Evol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1410","DOI":"10.1353\/hpu.2012.0146","article-title":"Four ways geographic information systems can help to enhance health service planning and delivery for infectious diseases in low-income countries","volume":"23","author":"Brijnath","year":"2012","journal-title":"J. Health Care Poor Underserved"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1016\/j.apgeog.2011.06.011","article-title":"Empirical mapping of suitability to dengue fever in Mexico using species distribution modeling","volume":"33","year":"2012","journal-title":"Appl. Geogr."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/j.actatropica.2018.05.003","article-title":"Modeling Dengue vector population using remotely sensed data and machine learning","volume":"185","author":"Scavuzzo","year":"2018","journal-title":"Acta Trop."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1016\/j.ecolmodel.2005.03.026","article-title":"Maximum entropy modeling of species geographic distributions","volume":"190","author":"Phillips","year":"2006","journal-title":"Ecol. Model."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1023\/A:1010933404324","article-title":"Classification and regression based on a forest of trees using random inputs","volume":"45","author":"Breiman","year":"2001","journal-title":"Mach. Learn."},{"key":"ref_24","first-page":"236","article-title":"Aftermath earthquake in Nepal: Burden of scrub typhus cases and their presentations","volume":"5","author":"Bastola","year":"2017","journal-title":"J. Trop. Dis."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Gautam, R., Parajuli, K., and Sherchand, J.B. (2019). Epidemiology, risk factors and seasonal variation of scrub typhus fever in Central Nepal. Trop. Med. Infect. Dis., 4.","DOI":"10.3390\/tropicalmed4010027"},{"key":"ref_26","first-page":"122","article-title":"Scrub typhus: An emerging neglected tropical disease in Nepal","volume":"14","author":"Upadhyaya","year":"2016","journal-title":"J. Nepal Health Res. Counc."},{"key":"ref_27","unstructured":"MoFALD (2017). Local Government Operative Act, 2017."},{"key":"ref_28","unstructured":"(1986). LRMP, Land System Report and Map, Land Resources Mapping Project\/HMG."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2775","DOI":"10.1175\/1520-0442(1999)012<2775:MTTITH>2.0.CO;2","article-title":"Maximum temperature trends in the Himalaya and its vicinity: An analysis based on temperature records from Nepal for the period 1971\u201394","volume":"12","author":"Shrestha","year":"1999","journal-title":"J. Clim."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Wei, Y., Huang, Y., Luo, L., Xiao, X., Liu, L., and Yang, Z. (2014). Rapid increase of scrub typhus: An epidemiology and spatial-temporal cluster analysis in Guangzhou City, Southern China, 2006\u20132012. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0101976"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1965","DOI":"10.1002\/joc.1276","article-title":"Very high resolution interpolated climate surfaces for global land areas","volume":"25","author":"Hijmans","year":"2005","journal-title":"Int. J. Climatol."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Acharya, B., Cao, C., Xu, M., Khanal, L., Naeem, S., and Pandit, S. (2018). Present and future of dengue fever in Nepal: Mapping climatic suitability by ecological Niche Model. Int. J. Environ. Res. Public. Health, 15.","DOI":"10.3390\/ijerph15020187"},{"key":"ref_33","unstructured":"Didan, K. (2015). MOD13A3 MODIS\/Terra vegetation indices monthly L3 global 1km SIN grid V006(Data set). NASA EOSDIS Land Process. DAAC."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.cageo.2016.08.020","article-title":"MODIStsp: An R package for automatic preprocessing of MODIS Land Products time series","volume":"97","author":"Busetto","year":"2016","journal-title":"Comput. Geosci."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1016\/j.jenvman.2014.07.047","article-title":"Development of 2010 national land cover database for the Nepal","volume":"148","author":"Uddin","year":"2015","journal-title":"J. Environ. Manag."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"504","DOI":"10.1038\/nature12060","article-title":"The global distribution and burden of dengue","volume":"496","author":"Bhatt","year":"2013","journal-title":"Nature"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1186\/1756-3305-7-289","article-title":"Modeling the distribution of the West Nile and Rift Valley Fever vector Culex pipiens in arid and semi-arid regions of the Middle East and North Africa","volume":"7","author":"Conley","year":"2014","journal-title":"Parasit. Vectors"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"253","DOI":"10.2307\/2288003","article-title":"Classification and Regression Trees","volume":"81","author":"Ryzin","year":"1986","journal-title":"J. Am. Stat. Assoc."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1111\/j.2041-210X.2011.00172.x","article-title":"Selecting pseudo-absences for species distribution models: How, where and how many?: How to use pseudo-absences in niche modelling?","volume":"3","author":"Jiguet","year":"2012","journal-title":"Methods Ecol. Evol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1016\/j.actatropica.2018.06.021","article-title":"Mapping the transmission risk of Zika virus using machine learning models","volume":"185","author":"Jiang","year":"2018","journal-title":"Acta Trop."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"513","DOI":"10.1186\/s13071-018-3097-9","article-title":"Environmental suitability for lymphatic filariasis in Nigeria","volume":"11","author":"Eneanya","year":"2018","journal-title":"Parasit. Vectors"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1223","DOI":"10.1111\/j.1365-2664.2006.01214.x","article-title":"Assessing the accuracy of species distribution models: Prevalence, kappa and the true skill statistic (TSS): Assessing the accuracy of distribution models","volume":"43","author":"Allouche","year":"2006","journal-title":"J. Appl. Ecol."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Kogo, B.K., Kumar, L., Koech, R., and Kariyawasam, C.S. (2019). Modelling climate suitability for rainfed Maize cultivation in Kenya using a Maximum Entropy (MaxENT) approach. Agronomy, 9.","DOI":"10.3390\/agronomy9110727"},{"key":"ref_44","unstructured":"Pun, S.B. (2018, December 12). Rise of scrub typhus: Urgent action required. Available online: https:\/\/thehimalayantimes.com\/opinion\/rise-of-scrub-typhus-urgent-action-required\/."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"2269","DOI":"10.1890\/10-1047.1","article-title":"Comparison of statistical and theoretical habitat models for conservation planning: The benefit of ensemble prediction","volume":"21","author":"Fearer","year":"2011","journal-title":"Ecol. Appl."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"586","DOI":"10.1016\/0035-9203(81)90210-8","article-title":"Antibodies to typhus in Eastern Nepal","volume":"75","author":"Brown","year":"1981","journal-title":"Trans. R. Soc. Trop. Med. Hyg."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Dorji, K., Phuentshok, Y., Zangpo, T., Dorjee, S., Dorjee, C., Jolly, P., Morris, R., Marquetoux, N., and McKenzie, J. (2019). Clinical and epidemiological patterns of scrub typhus, an emerging disease in Bhutan. Trop. Med. Infect. Dis., 4.","DOI":"10.3390\/tropicalmed4020056"},{"key":"ref_48","unstructured":"(2017). DoH, Annual Health Report (2015\/2016)."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1153","DOI":"10.1016\/j.trstmh.2009.02.006","article-title":"Scrub typhus in Darjeeling, India: Opportunities for simple, practical prevention measures","volume":"103","author":"Sharma","year":"2009","journal-title":"Trans. R. Soc. Trop. Med. Hyg."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1519","DOI":"10.1007\/s11442-018-1559-9","article-title":"Spatiotemporal changes in agricultural land cover in Nepal over the last 100 years","volume":"28","author":"Paudel","year":"2018","journal-title":"J. Geogr. Sci."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"e516","DOI":"10.1016\/S2214-109X(16)30094-8","article-title":"Typhoid versus typhus fever in post-earthquake Nepal","volume":"4","author":"Basnyat","year":"2016","journal-title":"Lancet Glob. Health"},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Park, S.-W., Ha, N.-Y., Ryu, B., Bang, J.H., Song, H., Kim, Y., Kim, G., Oh, M., Cho, N.-H., and Lee, J. (2015). Urbanization of scrub typhus disease in South Korea. PLoS Negl. Trop. Dis., 9.","DOI":"10.1371\/journal.pntd.0003814"}],"container-title":["International Journal of Environmental Research and Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-4601\/16\/23\/4845\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:39:22Z","timestamp":1760189962000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-4601\/16\/23\/4845"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,12,2]]},"references-count":52,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2019,12]]}},"alternative-id":["ijerph16234845"],"URL":"https:\/\/doi.org\/10.3390\/ijerph16234845","relation":{},"ISSN":["1660-4601"],"issn-type":[{"value":"1660-4601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,12,2]]}}}