The impact of environmental factors on human echinococcosis epidemics: spatial modelling and risk prediction

Trends in the disease burden of cystic echinococcosis in China, 1990-2044 analysis and forecasting study

This study aims to analyze changes in the disease burden of cystic echinococcosis in China from 1990 to 2019 and to predict trends from 2020 to 2044. Using the Global Burden of Disease 2019 (GBD 2019) database, we analyzed the trends in annual percentage change (APC) and average annual percentage change (AAPC) for incidence, prevalence, death, and disability-adjusted life years (DALY) rates of cystic echinococcosis in China via the Joinpoint Regression Program 4.8.0.1 software. Additionally, we applied Nordpred modeling to predict future trends in disease burden over the next 25 years. From 1990 to 2019, the incidence and prevalence of cystic echinococcosis in the Chinese population showed an overall increasing trend, whereas the death and DALY rates exhibited an overall decreasing trend. The disease burden of cystic echinococcosis was greater in males than in females, with significant differences across age groups. The highest incidence and prevalence rates were observed in the 10-24 years age group, whereas the lowest occurred in the 0-9 years age group. Fatalities and DALY rates increased with age, particularly in the 70 and older age groups. According to the Nordpred modeling results, the incidence, prevalence, and DALY rates of cystic echinococcosis in China are expected to rise slightly over the next 25 years. The overall disease burden of cystic echinococcosis is projected to increase gradually between 2020 and 2044, with men exhibiting higher incidence, prevalence, and DALY rates than women.

Prevalence and spatial distribution characteristics of human echinococcosis: A county-level modeling study in southern Xinjiang, China

Objectives

Human echinococcosis remains an important public health problem. The aim of this study was to analyze the prevalence and spatial distribution characteristics of human echinococcosis cases in southern Xinjiang, China from 2005 to 2021.

Methods

Human echinococcosis cases were collected from the National Infectious Disease Reporting System. Joinpoint regression analysis was performed to explore the trends. Spatial autocorrelation, hot spot analysis, as well as spatial-temporal clustering analysis were conducted to confirm the distribution and risk factors.

Results

A total of 4580 cases were reported in southern Xinjiang during 2005-2021, with a mean annual incidence of 2.56/100,000. Echinococcosis incidence showed an increasing trend from 2005 to 2017 (APC = 17.939, 95%CI: 13.985 to 22.029) and a decreasing trend from 2017 to 2021 (APC = -18.769, 95%CI: 28.157 to -8.154). Echinococcosis cases had a positive spatial autocorrelation in 2005-2021 (Moran's I = 0.19, P < 0.05). The disease hotspots were located in the east and west in these areas, then returned to the east clusters, including Hejing, Heshuo, Wuqia, Atushi, Aheqi, and Yanqi Hui Autonomous County. Meanwhile, spatial-temporal analysis identified the first cluster comprised of five counties (cities): Yanqi Hui Autonomous County, Korla City, Bohu County, Hejing County, and Heshuo County. And secondary clusters 1-3 are predominantly in Wushi County, Aheqi County, Keping County, Atushi City, Wuqia County and Cele County.

Conclusions

Our findings suggest that echinococcosis is still an important zoonotic parasitic disease in southern Xinjiang, yet it showed a certain degree of spatial clustering. It is crucial to implement comprehensive prevention and control measures to effectively combat the epidemic of echinococcosis.

Changes in the global epidemiological characteristics of cystic echinococcosis over the past 30 years and projections for the next decade: Findings from the Global Burden of Disease Study 2019

Background

Despite ongoing changes in the global epidemiology of cystic echinococcosis (CE), there is a lack of research conducted to date.

Methods

We extracted data on incidence and disability-adjusted life years for 204 countries and territories from 1990 to 2019 to evaluate the epidemiological characteristics and burden of CE through the Global Burden of Diseases, Injuries, and Risk Factors Study 2019. We used locally weighted linear regression to analyse the primary driving factors of the prevalence of CE at the national and regional levels and utilised a Bayesian Age-Period-Cohort model to forecast the global incidence of CE in the next decade.

Results

Globally, the incidence of CE remained constantly high from 1990 (2.65 per 100 000 population) to 2019 (2.60 per 100 000 population), resulting in an estimated 207 368 new cases in 2019. We observed substantial variations in the disease burden regarding its spatiotemporal distribution, population demographics, and Socio-Demographic Index levels. According to established models, factors such as health care capacity, livestock husbandry, agricultural activities, rural populations, and education levels are likely to play significant roles in determining the prevalence of CE across different countries. By 2030, the worldwide number of CE cases could reach as high as 235 628, representing an increase of 13.63% compared to 2019.

Conclusions

Over the past three decades, the global burden of CE has persistently remained high, especially in Central Asia, as well as North Africa and the Middle East. Efforts should focus on more effective prevention and control measures in these key regions and should specifically target vulnerable populations to prevent the escalation of epidemics.

Epidemiological characteristics and risk factors for cystic and alveolar echinococcosis in China: an analysis of a national population-based field survey

BACKGROUND

Human cystic and alveolar echinococcosis are neglected tropical diseases that WHO has prioritized for control in recent years. Both diseases impose substantial burdens on public health and the socio-economy in China. In this study, which is based on the national echinococcosis survey from 2012 to 2016, we aim to describe the spatial prevalence and demographic characteristics of cystic and alveolar echinococcosis infections in humans and assess the impact of environmental, biological and social factors on both types of the disease.

METHODS

We computed the sex-, age group-, occupation- and education level-specific prevalences of cystic and alveolar echinococcosis at national and sub-national levels. We mapped the geographical distribution of echinococcosis prevalence at the province, city and county levels. Finally, by analyzing the county-level echinococcosis cases combined with a range of associated environmental, biological and social factors, we identified and quantified the potential risk factors for echinococcosis using a generalized linear model.

RESULTS

A total of 1,150,723 residents were selected and included in the national echinococcosis survey between 2012 and 2016, of whom 4161 and 1055 tested positive for cystic and alveolar echinococcosis, respectively. Female gender, older age, occupation at herdsman, occupation as religious worker and illiteracy were identified as risk factors for both types of echinococcosis. The prevalence of echinococcosis was found to vary geographically, with areas of high endemicity observed in the Tibetan Plateau region. Cystic echinococcosis prevalence was positively correlated with cattle density, cattle prevalence, dog density, dog prevalence, number of livestock slaughtered, elevation and grass area, and negatively associated with temperature and gross domestic product (GDP). Alveolar echinococcosis prevalence was positively correlated with precipitation, level of awareness, elevation, rodent density and rodent prevalence, and negatively correlated with forest area, temperature and GDP. Our results also implied that drinking water sources are significantly associated with both diseases.

CONCLUSIONS

The results of this study provide a comprehensive understanding of geographical patterns, demographic characteristics and risk factors of cystic and alveolar echinococcosis in China. This important information will contribute towards developing targeted prevention measures and controlling diseases from the public health perspective.

The Impact of Environmental and Host Factors on Human Cystic Echinococcosis: A County-Level Modeling Study in Western China

Human cystic echinococcosis (CE) is a parasitic disease caused by tapeworms from the Echinococcus granulosus genus, potentially affected by the environment and host animals. West China is one of the most endemic areas of human CE nation and worldwide. The current study identifies the crucial environmental and host factors of human CE prevalence in the Qinghai-Tibet Plateau and non-Qinghai-Tibet Plateau regions. An optimal county-level model was used to analyze the association between key factors and human CE prevalence within the Qinghai-Tibet Plateau. Geodetector analysis and multicollinearity tests identify key factors, and an optimal model is developed through generalized additive models. In the Qinghai-Tibet Plateau, four key factors were identified from the 88 variables, such as maximum annual precipitation (Pre), maximum summer normalized difference vegetation index (NDVI), Tibetan population rate (TibetanR), and positive rates of Echinococcus coproantigen in dogs (DogR). Based on the optimal model, a significant positive linear relationship was observed between maximum annual Pre and human CE prevalence. A probable U-shaped curve depicts the non-linear relationship between maximum summer NDVI and the human CE prevalence. Human CE prevalence possesses significant positive non-linear relationships with TibetanR and DogR. Human CE transmission is integrally affected by environmental and host factors. This explains the mechanism of human CE transmission based on the pathogen, host, and transmission framework. Therefore, the current study provides references and innovative ideas for preventing and controlling human CE in western China.

The impact of natural environment on human alveolar echinococcosis: A township-level modeling study in Qinghai-Tibet Plateau

Human alveolar echinococcosis (AE) is a lethal helminthic infection caused by the tapeworms Echinococcus multilocularis. The Qinghai-Tibet Plateau has the greatest endemicity of human AE globally, but the natural risk factors and its impact mechanism are still unclear. Generalized linear models and generalized additive models are used to select key linear and non-linear environmental factors associated with cases of AE. The interactive effect between different factors is identified using concurvity test. From fifty-nine variables analyzed, four key factors and one interaction term were identified associated with AE. Considering interaction terms between climatic and geographical landscape factors can significantly improve model fitting. Minimum winter precipitation, percentage of grassland cover, and minimum elevation have significant positive linear relationship with human AE incidence. The relationship between maximum summer precipitation and human AE is non-linear with high AE incidence associated with moderate precipitation. The interaction term of maximum summer precipitation and number of patches of grassland on human AE indicates that human AE incidence is highest when both factors were high. The climatic and landscape risk factors together are associated with the local transmission of human AE in Qinghai-Tibet Plateau. This study provides a scientific basis for human intervention in AE from fine-scale ecological environment.