Wenyi Zhang - Academia.edu (original) (raw)

Papers by Wenyi Zhang

PloS one, 2015

To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the ... more To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the spatiotemporal clusters at the county level for preemptive public health interventions, and evaluate the differences in the epidemiological characteristics within and outside clusters. CA cases reported during 2005-2012 from the national surveillance system were evaluated at the county level using space-time scan statistic. Comparative analysis of the epidemic characteristics within and outside identified clusters was performed using using the χ2 test or Kruskal-Wallis test. The group of 30-39 years had the highest incidence of CA, and the fatality rate increased with age, with persons ≥70 years showing a fatality rate of 4.04%. Seasonality analysis showed that most of CA cases occurred between May/June and September/October of each year. The primary spatiotemporal cluster contained 19 counties from June 2006 to May 2010, and it was mainly located straddling the borders of Sichuan, Gansu...

Computational and Mathematical Methods in Medicine, 2018

In order to analyze the spread of avian influenza A (H7N9), we construct an avian influenza trans... more In order to analyze the spread of avian influenza A (H7N9), we construct an avian influenza transmission model from poultry (including poultry farm, backyard poultry farm, live-poultry wholesale market, and wet market) to human according to poultry transport network. We obtain the threshold value for the prevalence of avian influenza A (H7N9) and also give the existence and number of the boundary equilibria and endemic equilibria in different conditions. We can see that poultry transport network plays an important role in controlling avian influenza A (H7N9). Finally, numerical simulations are presented to illustrate the effects of poultry in different places on avian influenza. In order to reduce human infections in China, our results suggest that closing the retail live-poultry market or preventing the poultry of backyard poultry farm into the live-poultry market is feasible in a suitable condition.

Environment international, 2014

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public... more Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km×1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, wi...

The Lancet Planetary Health, 2017

Background China is experiencing severe ambient air pollution. However, few studies anywhere have... more Background China is experiencing severe ambient air pollution. However, few studies anywhere have examined the health effects of PM 1 (particulate matter with aerodynamic diameter <1 μm), which are a major part of PM 2•5 (particulate matter with aerodynamic diameter <2•5 μm) and even potentially more harmful than PM 2•5. We aimed to estimate the effects of ambient daily PM 1 and PM 2•5 concentrations on emergency hospital visits in China. Methods In this epidemiological study, we collected daily counts of emergency hospital visits from the 28 largest hospitals in 26 Chinese cities from Sept 9, 2013, to Dec 31, 2014. Ground-based monitoring data for PM 1 and PM 2•5 and meteorological data were also collected. Hospital-specific emergency hospital visits associated with PM 1 or PM 2•5 were evaluated with a time-series Poisson regression. The effect estimates were then pooled at the country level using a random-effects meta-analysis. Findings The mean daily concentration of PM 1 in all cities was 42•5 µg/m³ (SD 34•6) and of PM 2•5 was 51•9 µg/m³ (41•5). The mean daily number of emergency hospital visits in all hospitals was 278 (SD 173). PM 1 and PM 2•5 concentrations were significantly associated with an increased risk of emergency hospital visits at lag 0-2 days (cumulative relative risk [RRs] 1•011 [95% CI 1•006-1•017] for a 10 µg/m³ increase in PM 1 and 1•010 [1•005-1•016] for a 10 µg/m³ increase in PM 2•5). Slightly higher RRs of ambient PM 1 and PM 2•5 pollution were noted among women and children than among men and adults, respectively, but without statistical significance. Given a cause-effect association, 4•47% (95% CI 2•05-6•79) and 5•05% (2•23-7•75) of daily emergency hospital visits in China could be attributed to ambient PM 1 and PM 2•5 pollution, respectively. Interpretation Exposure to both ambient PM 1 and PM 2•5 were significantly associated with increased emergency hospital visits. The results suggest that most of the health effects of PM 2•5 come from PM 1 .

Acta tropica, Jan 13, 2016

Zika virus (ZIKV) is an emerging arbovirus transmitted to humans by Aedes mosquitoes, the same ve... more Zika virus (ZIKV) is an emerging arbovirus transmitted to humans by Aedes mosquitoes, the same vectors that transmit dengue virus and chikungunya. Recent work has suggested that prior infection with dengue could lead to more severe clinical disease in ZIKV patients. Here, we describe the spatial distribution of and clinical symptoms experienced by ZIKV cases in Mexico. We performed Fisher's Exact test and Pearson's Chi-Square tests on data from Mexico's national surveillance system on the demographic and clinical characteristics of ZIKV patients (N=84), and then a multivariate logistic regression analysis to determine demographic risk factors for patients presenting with at least 9 symptoms. We also mapped the cases to describe the spatial distribution of ZIKV in Mexico. Results from the multivariate logistic regression analysis indicate that, controlling for all covariates, sex (male) is a significant protective factor in reporting a high number of symptoms (OR=0.36, 95...

PLoS neglected tropical diseases, Jun 1, 2018

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-associated zoonosis caused by hantavirus... more Hemorrhagic fever with renal syndrome (HFRS) is a rodent-associated zoonosis caused by hantavirus. The HFRS was initially detected in northeast China in 1931, and since 1955 it has been detected in many regions of the country. Global climate dynamics influences HFRS spread in a complex nonlinear way. The quantitative assessment of the spatiotemporal variation of the "HFRS infections-global climate dynamics" association at a large geographical scale and during a long time period is still lacking. This work is the first study of a recently completed dataset of monthly HFRS cases in Eastern China during the period 2005-2016. A methodological synthesis that involves a time-frequency technique, a composite space-time model, hotspot analysis, and machine learning is implemented in the study of (a) the association between HFRS incidence spread and climate dynamics and (b) the geographic factors impacting this association over Eastern China during the period 2005-2016. The results...

Environmental health perspectives, Apr 20, 2018

There is limited evidence about the association between ambient temperature and the incidence of ... more There is limited evidence about the association between ambient temperature and the incidence of pediatric hand, foot, and mouth disease (HFMD) nationwide in China. We examined the childhood temperature-HFMD associations across mainland China, and we projected the change in HFMD cases due to projected temperature change by the 2090s. Data on daily HFMD (children 0-14 y old) counts and weather were collected from 362 sites during 2009-2014. Daily temperature by the 2090s was downscaled under the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Temperature-HFMD associations were quantified using a two-stage Poisson regression with a distributed lag nonlinear model. The impact of changes in temperature on the incidence of HFMD was estimated by combining the fitted temperature-HFMD associations with projected temperatures under each scenario, assuming a constant population structure. Sensitivity analyses were performed to assess the influence of primary model assumption...

Background: The unprecedented size of the 2014 Ebola Virus Disease (EVD) outbreak in West Africa ... more Background: The unprecedented size of the 2014 Ebola Virus Disease (EVD) outbreak in West Africa has allowed for a more extensive characterization of the clinical presentation and management of this disease. In this study, we report the trends in morbidity, mortality, and determinants of patient survival as EVD spread into Bong County, Liberia.

Clinical and spatial features of Zika virus in Mexico.Acta Tropica http://dx.

Background: Botswana significantly reduced its malaria burden between 2000 and 2012. Incidence dr... more Background: Botswana significantly reduced its malaria burden between 2000 and 2012. Incidence dropped from 0.99 to 0.01 % and deaths attributed to malaria declined from 12 to 3. The country initiated elimination strategies in October 2012. We examine the progress and challenges during implementation and identify future needs for a successful program in Botswana. Methods: A national, rapid notification and response strategy was developed. Cases detected through the routine passive surveillance system at health facilities were intended to initiate screening of contacts around a positive case during follow up. Positive cases were reported to district health management teams to activate district rapid response teams (DRRT). The health facility and the DRRT were to investigate the cases, and screen household members within 100 m of case households within 48 h of notification using rapid diagnostic tests (RDT) and microscopy. Positive malaria cases detected in health facilities were used for spatial analysis. Results: There were 1808 malaria cases recorded in Botswana during 26 months from October, 2012 to December, 2014. Males were more frequently infected (59 %) than females. Most cases (60 %) were reported from Okavango district which experienced an outbreak in 2013 and 2014. Among the factors creating challenges for malaria eradication, only 1148 cases (63.5 %) were captured by the required standardized notification forms. In total, 1080 notified cases were diagnosed by RDT. Of the positive malaria cases, only 227 (12.6 %) were monitored at the household level. One hundred (8.7 %) cases were associated with national or transnational movement of patients. Local movements of infected individuals within Botswana accounted for 31 cases while 69 (6.01 %) cases were imported from other countries. Screening individuals in and around index households identified 37 additional, asymptomatic infections. Oscillating, sporadic and new malaria hot-spots were detected in Botswana during the study period. Conclusion: Botswana's experience shows some of the practical challenges of elimination efforts. Among them are the substantial movements of human infections within and among countries, and the persistence of asymptomatic reservoir infections. Programmatically, challenges include improving the speed of communicating and improving the thoroughness when responding to newly identified cases. The country needs further sustainable interventions to target infections if it is to successfully achieve its elimination goal.

PLoS Neglected Tropical Diseases, 2014

Background: Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many... more Background: Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes of hantaviruses. In China, HFRS has been recognized as a severe public health problem with 90% of the total reported cases in the world. This study describes the spatiotemporal dynamics of HFRS cases in China and identifies the regions, time, and populations at highest risk, which could help the planning and implementation of key preventative measures.

To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the ... more To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the spatiotemporal clusters at the county level for preemptive public health interventions, and evaluate the differences in the epidemiological characteristics within and outside clusters.

Environment International, 2014

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public... more Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km × 1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, with local spatial variations in probability influenced by minimum temperatures, human population density, mean temperatures, and elevation, with contribution of 17.94%-38.37%, 15.47%-21.82%, 3.86%-21.22%, and 12.05%-16.02%, respectively. Approximately 60% of JE cases occurred in predicted high risk areas, which covered less than 6% of areas in mainland China. Our findings will help inform optimal geographical allocation of the limited resources available for JE prevention and control in China, find hidden high-risk areas, and increase the effectiveness of public health interventions against JE transmission.

BACKGROUND: Malaria in pregnancy (MiP) is a major concern in Zambia. Here we aim to determine the... more BACKGROUND: Malaria in pregnancy (MiP) is a major concern in Zambia. Here we aim to determine the burden and risk factors of MiP.METHODS: Monthly reported district-level malaria cases among pregnant women (count data) from January 2009 to December 2014 were obtained from the Zambian District Health Information System. Negative binomial regression model was used to investigate the associations between vector control tools, coverage of health care facilities, transportation networks and population density. Data on MiP treatment were obtained from the 2012 Zambian Malaria Indicator Survey. Yearly clusters of MiP were investigated using spatial statistics in ArcGIS v 10.1.RESULTS: The results indicated that MiP decreased in Zambia between 2010 and 2013. MiP was observed throughout the year, but showed a strong seasonal pattern. Persistent hotspots of MiP were reported in the southeast and northeast regions of Zambia, with districts that had better access to rail road and presence of water bodies associated with decreased prevalence of MiP. Better indoor residual spraying and long-lasting insecticide-treated nets coverage was demonstrated to be protective against MiP.CONCLUSIONS: Mapping the distribution of MiP to track the future requirements for scaling up essential disease-prevention efforts in stable hotspots can help the Zambian National Malaria Control Center to further develop strategies to reduce malaria prevalence in this vulnerable sub-population.© The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Environment international, 2014

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public... more Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km×1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, wi...

PLoS neglected tropical diseases, 2014

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes o... more Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes of hantaviruses. In China, HFRS has been recognized as a severe public health problem with 90% of the total reported cases in the world. This study describes the spatiotemporal dynamics of HFRS cases in China and identifies the regions, time, and populations at highest risk, which could help the planning and implementation of key preventative measures. Data on all reported HFRS cases at the county level from January 2005 to December 2012 were collected from Chinese Center for Disease Control and Prevention. Geographic Information System-based spatiotemporal analyses including Local Indicators of Spatial Association and Kulldorff's space-time scan statistic were performed to detect local high-risk space-time clusters of HFRS in China. In addition, cases from high-risk and low-risk counties were compared to identify significant demographic differences. A total of 100,868 cases were repo...

PloS one, 2015

To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the ... more To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the spatiotemporal clusters at the county level for preemptive public health interventions, and evaluate the differences in the epidemiological characteristics within and outside clusters. CA cases reported during 2005-2012 from the national surveillance system were evaluated at the county level using space-time scan statistic. Comparative analysis of the epidemic characteristics within and outside identified clusters was performed using using the χ2 test or Kruskal-Wallis test. The group of 30-39 years had the highest incidence of CA, and the fatality rate increased with age, with persons ≥70 years showing a fatality rate of 4.04%. Seasonality analysis showed that most of CA cases occurred between May/June and September/October of each year. The primary spatiotemporal cluster contained 19 counties from June 2006 to May 2010, and it was mainly located straddling the borders of Sichuan, Gansu...

Computational and Mathematical Methods in Medicine, 2018

In order to analyze the spread of avian influenza A (H7N9), we construct an avian influenza trans... more In order to analyze the spread of avian influenza A (H7N9), we construct an avian influenza transmission model from poultry (including poultry farm, backyard poultry farm, live-poultry wholesale market, and wet market) to human according to poultry transport network. We obtain the threshold value for the prevalence of avian influenza A (H7N9) and also give the existence and number of the boundary equilibria and endemic equilibria in different conditions. We can see that poultry transport network plays an important role in controlling avian influenza A (H7N9). Finally, numerical simulations are presented to illustrate the effects of poultry in different places on avian influenza. In order to reduce human infections in China, our results suggest that closing the retail live-poultry market or preventing the poultry of backyard poultry farm into the live-poultry market is feasible in a suitable condition.

Environment international, 2014

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public... more Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km×1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, wi...

The Lancet Planetary Health, 2017

Background China is experiencing severe ambient air pollution. However, few studies anywhere have... more Background China is experiencing severe ambient air pollution. However, few studies anywhere have examined the health effects of PM 1 (particulate matter with aerodynamic diameter <1 μm), which are a major part of PM 2•5 (particulate matter with aerodynamic diameter <2•5 μm) and even potentially more harmful than PM 2•5. We aimed to estimate the effects of ambient daily PM 1 and PM 2•5 concentrations on emergency hospital visits in China. Methods In this epidemiological study, we collected daily counts of emergency hospital visits from the 28 largest hospitals in 26 Chinese cities from Sept 9, 2013, to Dec 31, 2014. Ground-based monitoring data for PM 1 and PM 2•5 and meteorological data were also collected. Hospital-specific emergency hospital visits associated with PM 1 or PM 2•5 were evaluated with a time-series Poisson regression. The effect estimates were then pooled at the country level using a random-effects meta-analysis. Findings The mean daily concentration of PM 1 in all cities was 42•5 µg/m³ (SD 34•6) and of PM 2•5 was 51•9 µg/m³ (41•5). The mean daily number of emergency hospital visits in all hospitals was 278 (SD 173). PM 1 and PM 2•5 concentrations were significantly associated with an increased risk of emergency hospital visits at lag 0-2 days (cumulative relative risk [RRs] 1•011 [95% CI 1•006-1•017] for a 10 µg/m³ increase in PM 1 and 1•010 [1•005-1•016] for a 10 µg/m³ increase in PM 2•5). Slightly higher RRs of ambient PM 1 and PM 2•5 pollution were noted among women and children than among men and adults, respectively, but without statistical significance. Given a cause-effect association, 4•47% (95% CI 2•05-6•79) and 5•05% (2•23-7•75) of daily emergency hospital visits in China could be attributed to ambient PM 1 and PM 2•5 pollution, respectively. Interpretation Exposure to both ambient PM 1 and PM 2•5 were significantly associated with increased emergency hospital visits. The results suggest that most of the health effects of PM 2•5 come from PM 1 .

Acta tropica, Jan 13, 2016

Zika virus (ZIKV) is an emerging arbovirus transmitted to humans by Aedes mosquitoes, the same ve... more Zika virus (ZIKV) is an emerging arbovirus transmitted to humans by Aedes mosquitoes, the same vectors that transmit dengue virus and chikungunya. Recent work has suggested that prior infection with dengue could lead to more severe clinical disease in ZIKV patients. Here, we describe the spatial distribution of and clinical symptoms experienced by ZIKV cases in Mexico. We performed Fisher's Exact test and Pearson's Chi-Square tests on data from Mexico's national surveillance system on the demographic and clinical characteristics of ZIKV patients (N=84), and then a multivariate logistic regression analysis to determine demographic risk factors for patients presenting with at least 9 symptoms. We also mapped the cases to describe the spatial distribution of ZIKV in Mexico. Results from the multivariate logistic regression analysis indicate that, controlling for all covariates, sex (male) is a significant protective factor in reporting a high number of symptoms (OR=0.36, 95...

PLoS neglected tropical diseases, Jun 1, 2018

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-associated zoonosis caused by hantavirus... more Hemorrhagic fever with renal syndrome (HFRS) is a rodent-associated zoonosis caused by hantavirus. The HFRS was initially detected in northeast China in 1931, and since 1955 it has been detected in many regions of the country. Global climate dynamics influences HFRS spread in a complex nonlinear way. The quantitative assessment of the spatiotemporal variation of the "HFRS infections-global climate dynamics" association at a large geographical scale and during a long time period is still lacking. This work is the first study of a recently completed dataset of monthly HFRS cases in Eastern China during the period 2005-2016. A methodological synthesis that involves a time-frequency technique, a composite space-time model, hotspot analysis, and machine learning is implemented in the study of (a) the association between HFRS incidence spread and climate dynamics and (b) the geographic factors impacting this association over Eastern China during the period 2005-2016. The results...

Environmental health perspectives, Apr 20, 2018

There is limited evidence about the association between ambient temperature and the incidence of ... more There is limited evidence about the association between ambient temperature and the incidence of pediatric hand, foot, and mouth disease (HFMD) nationwide in China. We examined the childhood temperature-HFMD associations across mainland China, and we projected the change in HFMD cases due to projected temperature change by the 2090s. Data on daily HFMD (children 0-14 y old) counts and weather were collected from 362 sites during 2009-2014. Daily temperature by the 2090s was downscaled under the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Temperature-HFMD associations were quantified using a two-stage Poisson regression with a distributed lag nonlinear model. The impact of changes in temperature on the incidence of HFMD was estimated by combining the fitted temperature-HFMD associations with projected temperatures under each scenario, assuming a constant population structure. Sensitivity analyses were performed to assess the influence of primary model assumption...

Background: The unprecedented size of the 2014 Ebola Virus Disease (EVD) outbreak in West Africa ... more Background: The unprecedented size of the 2014 Ebola Virus Disease (EVD) outbreak in West Africa has allowed for a more extensive characterization of the clinical presentation and management of this disease. In this study, we report the trends in morbidity, mortality, and determinants of patient survival as EVD spread into Bong County, Liberia.

Clinical and spatial features of Zika virus in Mexico.Acta Tropica http://dx.

Background: Botswana significantly reduced its malaria burden between 2000 and 2012. Incidence dr... more Background: Botswana significantly reduced its malaria burden between 2000 and 2012. Incidence dropped from 0.99 to 0.01 % and deaths attributed to malaria declined from 12 to 3. The country initiated elimination strategies in October 2012. We examine the progress and challenges during implementation and identify future needs for a successful program in Botswana. Methods: A national, rapid notification and response strategy was developed. Cases detected through the routine passive surveillance system at health facilities were intended to initiate screening of contacts around a positive case during follow up. Positive cases were reported to district health management teams to activate district rapid response teams (DRRT). The health facility and the DRRT were to investigate the cases, and screen household members within 100 m of case households within 48 h of notification using rapid diagnostic tests (RDT) and microscopy. Positive malaria cases detected in health facilities were used for spatial analysis. Results: There were 1808 malaria cases recorded in Botswana during 26 months from October, 2012 to December, 2014. Males were more frequently infected (59 %) than females. Most cases (60 %) were reported from Okavango district which experienced an outbreak in 2013 and 2014. Among the factors creating challenges for malaria eradication, only 1148 cases (63.5 %) were captured by the required standardized notification forms. In total, 1080 notified cases were diagnosed by RDT. Of the positive malaria cases, only 227 (12.6 %) were monitored at the household level. One hundred (8.7 %) cases were associated with national or transnational movement of patients. Local movements of infected individuals within Botswana accounted for 31 cases while 69 (6.01 %) cases were imported from other countries. Screening individuals in and around index households identified 37 additional, asymptomatic infections. Oscillating, sporadic and new malaria hot-spots were detected in Botswana during the study period. Conclusion: Botswana's experience shows some of the practical challenges of elimination efforts. Among them are the substantial movements of human infections within and among countries, and the persistence of asymptomatic reservoir infections. Programmatically, challenges include improving the speed of communicating and improving the thoroughness when responding to newly identified cases. The country needs further sustainable interventions to target infections if it is to successfully achieve its elimination goal.

PLoS Neglected Tropical Diseases, 2014

Background: Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many... more Background: Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes of hantaviruses. In China, HFRS has been recognized as a severe public health problem with 90% of the total reported cases in the world. This study describes the spatiotemporal dynamics of HFRS cases in China and identifies the regions, time, and populations at highest risk, which could help the planning and implementation of key preventative measures.

To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the ... more To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the spatiotemporal clusters at the county level for preemptive public health interventions, and evaluate the differences in the epidemiological characteristics within and outside clusters.

Environment International, 2014

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public... more Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km × 1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, with local spatial variations in probability influenced by minimum temperatures, human population density, mean temperatures, and elevation, with contribution of 17.94%-38.37%, 15.47%-21.82%, 3.86%-21.22%, and 12.05%-16.02%, respectively. Approximately 60% of JE cases occurred in predicted high risk areas, which covered less than 6% of areas in mainland China. Our findings will help inform optimal geographical allocation of the limited resources available for JE prevention and control in China, find hidden high-risk areas, and increase the effectiveness of public health interventions against JE transmission.

BACKGROUND: Malaria in pregnancy (MiP) is a major concern in Zambia. Here we aim to determine the... more BACKGROUND: Malaria in pregnancy (MiP) is a major concern in Zambia. Here we aim to determine the burden and risk factors of MiP.METHODS: Monthly reported district-level malaria cases among pregnant women (count data) from January 2009 to December 2014 were obtained from the Zambian District Health Information System. Negative binomial regression model was used to investigate the associations between vector control tools, coverage of health care facilities, transportation networks and population density. Data on MiP treatment were obtained from the 2012 Zambian Malaria Indicator Survey. Yearly clusters of MiP were investigated using spatial statistics in ArcGIS v 10.1.RESULTS: The results indicated that MiP decreased in Zambia between 2010 and 2013. MiP was observed throughout the year, but showed a strong seasonal pattern. Persistent hotspots of MiP were reported in the southeast and northeast regions of Zambia, with districts that had better access to rail road and presence of water bodies associated with decreased prevalence of MiP. Better indoor residual spraying and long-lasting insecticide-treated nets coverage was demonstrated to be protective against MiP.CONCLUSIONS: Mapping the distribution of MiP to track the future requirements for scaling up essential disease-prevention efforts in stable hotspots can help the Zambian National Malaria Control Center to further develop strategies to reduce malaria prevalence in this vulnerable sub-population.© The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Environment international, 2014

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public... more Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km×1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, wi...

PLoS neglected tropical diseases, 2014

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes o... more Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes of hantaviruses. In China, HFRS has been recognized as a severe public health problem with 90% of the total reported cases in the world. This study describes the spatiotemporal dynamics of HFRS cases in China and identifies the regions, time, and populations at highest risk, which could help the planning and implementation of key preventative measures. Data on all reported HFRS cases at the county level from January 2005 to December 2012 were collected from Chinese Center for Disease Control and Prevention. Geographic Information System-based spatiotemporal analyses including Local Indicators of Spatial Association and Kulldorff's space-time scan statistic were performed to detect local high-risk space-time clusters of HFRS in China. In addition, cases from high-risk and low-risk counties were compared to identify significant demographic differences. A total of 100,868 cases were repo...