Spatiotemporal patterns and environmental drivers of human echinococcoses over a twenty-year period in Ningxia Hui Autonomous Region, China

Angela M Cadavid Restrepo,Tamsin S Barnes,Ricardo J Soares Magalhães,Archie C A Clements,Donald P Mcmanus,Nicholas A S Hamm,Darren J Gray,Yu Rong Yang,Gail M Williams

doi:10.1186/s13071-018-2693-z

Abstract

BackgroundHuman cystic (CE) and alveolar (AE) echinococcoses are zoonotic parasitic diseases that can be influenced by environmental variability and change through effects on the parasites, animal intermediate and definitive hosts, and human populations. We aimed to assess and quantify the spatiotemporal patterns of human echinococcoses in Ningxia Hui Autonomous Region (NHAR), China between January 1994 and December 2013, and examine associations between these infections and indicators of environmental variability and change, including large-scale landscape regeneration undertaken by the Chinese authorities.MethodsData on the number of human echinococcosis cases were obtained from a hospital-based retrospective survey conducted in NHAR for the period 1 January 1994 through 31 December 2013. High-resolution imagery from Landsat 4/5-TM and 8-OLI was used to create single date land cover maps. Meteorological data were also collected for the period January 1980 to December 2013 to derive time series of bioclimatic variables. A Bayesian spatio-temporal conditional autoregressive model was used to quantify the relationship between annual cases of CE and AE and environmental variables.ResultsAnnual CE incidence demonstrated a negative temporal trend and was positively associated with winter mean temperature at a 10-year lag. There was also a significant, nonlinear effect of annual mean temperature at 13-year lag. The findings also revealed a negative association between AE incidence with temporal moving averages of bareland/artificial surface coverage and annual mean temperature calculated for the period 11–15 years before diagnosis and winter mean temperature for the period 0–4 years. Unlike CE risk, the selected environmental covariates accounted for some of the spatial variation in the risk of AE.ConclusionsThe present study contributes towards efforts to understand the role of environmental factors in determining the spatial heterogeneity of human echinococcoses. The identification of areas with high incidence of CE and AE may assist in the development and refinement of interventions for these diseases, and enhanced environmental change risk assessment.

Highlights

Human cystic (CE) and alveolar (AE) echinococcoses are zoonotic parasitic diseases that can be influenced by environmental variability and change through effects on the parasites, animal intermediate and definitive hosts, and human populations
Based on reports from the Chinese Ministry of Health, more than 98% of patients with human echinococcoses originate from Gansu, Qinghai and Sichuan Provinces and from Xinjiang Uygur, Ningxia Hui and Inner Mongolia Autonomous Regions [5]
Using geographical information systems (GIS), Earth observation data and a Bayesian statistical framework, the present study describes the spatio-temporal patterns of CE and AE in Ningxia Hui Autonomous Region (NHAR) between January 1994 and December 2013

Summary

Introduction

Human cystic (CE) and alveolar (AE) echinococcoses are zoonotic parasitic diseases that can be influenced by environmental variability and change through effects on the parasites, animal intermediate and definitive hosts, and human populations. Cystic (CE) and alveolar (AE) echinococcoses, caused by Echinococcus granulosus and E. multilocularis, respectively, are the two forms of human echinococcosis of major public health importance worldwide [1] Both diseases are distributed widely and potentially life threatening if left untreated [2,3,4]. Based on reports from the Chinese Ministry of Health, more than 98% of patients with human echinococcoses originate from Gansu, Qinghai and Sichuan Provinces and from Xinjiang Uygur, Ningxia Hui and Inner Mongolia Autonomous Regions [5] These regions constitute highly endemic areas for these diseases in East Asia, significant differences in parasite prevalences have been demonstrated at regional and local levels [6,7,8]. Understanding how environmental and social factors interact to determine parasite transmission is essential for the design and implementation of effective strategies against echinococcosis, and to target resources to the communities most in need

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