Search

Scrub typhus is a climate-sensitive and life-threatening vector-borne disease that poses a growing public health threat. Although the climate-epidemic associations of many vector-borne diseases have been studied for decades, the impacts of climate on scrub typhus remain poorly understood, especially in the context of global warming. Here we incorporate Chinese national surveillance data on scrub typhus from 2010 to 2019 into a climate-driven generalized additive mixed model to explain the spatiotemporal dynamics of this disease and predict how it may be affected by climate change under various representative concentration pathways (RCPs) for three future time periods (the 2030s, 2050s, and 2080s). Our results demonstrate that temperature, precipitation, and relative humidity play key roles in driving the seasonal epidemic of scrub typhus in mainland China with a 2-month lag. Our findings show that the change of projected spatiotemporal dynamics of scrub typhus will be heterogeneous and will depend on specific combinations of regional climate conditions in future climate scenarios. Our results contribute to a better understanding of spatiotemporal dynamics of scrub typhus, which can help public health authorities refine their prevention and control measures to reduce the risks resulting from climate change.

A multitude of epidemiological studies have demonstrated that both ambient temperatures and air pollution are closely related to health outcomes. However, whether temperature has modification effects on the association between ozone and health outcomes is still debated. In this study, Three parallel time-series Poisson generalized additive models (GAMs) were used to examine the effects of modifying ambient temperatures on the association between ozone and mortality (including non-accidental, respiratory, and cardiovascular mortality) in Chengdu, China, from 2014 to 2016. The results confirmed that the ambient high temperatures strongly amplified the adverse effects of ozone on human mortality; specifically, the ozone effects were most pronounced at >28°C. Without temperature stratification conditions, a 10-µg/m3 increase in the maximum 8-hour average ozone (O3−8hmax) level at lag01 was associated with increases of 0.40% (95% confidence interval [CI]: 0.15%, 0.65%), 0.61% (95%CI: 0.27%, 0.95%) and 0.69% (95%CI: 0.34%, 1.04%) in non-accidental, respiratory, and cardiovascular mortality, respectively. On days during which the temperature exceeded 28°C, a 10-µg/m3 increase in O3−8hmax led to increases of 2.22% (95%CI: 1.21%, 3.23%), 2.67% (95%CI: 0.57%, 4.76%), and 4.13% (95%CI: 2.34%, 5.92%) in non-accidental, respiratory, and cardiovascular mortality, respectively. Our findings validated that high temperature could further aggravate the health risks of O3−8hmax, thus mitigating ozone exposure will be brought into the limelight especially under the context of changing climate.

Ambient air temperature is a key factor affecting human health. Adverse effects of extreme weather on mortality have been well explored and expounded in numerous epidemiological studies. The relationship between moderate temperature and mortality is, however, underexplored. This study quantitatively investigated the temperature-dependent mortality burden in China. Data on daily average temperature and mortality in 15 Chinese cities during 2010–2016 were collected for this study. The association between temperature and city-specific mortality was investigated with a quasi-Poisson regression combined with a distributed lag nonlinear model across lag 0–21 days. The results were then included in a multivariate meta-analysis to derive the pooled estimates of the effect of temperature on mortality at the multi-city level. Mortality fractions attributable to cold and heat (i.e., at temperatures below and above the minimum mortality temperature (MMT)) were calculated. Additionally, temperature ranges were further divided into 1 °C intervals of ambient temperature, and the attributable fractions were calculated for each range. The MMT varied from the 71th to 93th percentiles of temperature in the 15 Chinese cities, centering at the 78th percentile at the multi-city level. In total, 12.65% of non-accidental mortality was attributable to non-optimum temperature, of which cold and hot temperatures corresponded to attributable fractions of 11.38% and 1.27%, respectively. The results of temperature stratifications suggested that moderately cold temperatures provided the highest contribution to mortality caused by temperature. Specifically, the highest attributable fractions were at 7 °C, 7 °C, 8 °C, 8 °C, 4 °C, 4 °C, 5 °C, 7 °C, 7 °C, 4 °C, 5 °C, 5 °C, 6 °C, 11 °C, and 12 °C, for Harbin, Changchun, Shenyang, Urumqi, Beijing, Tianjin, Shijiazhuang, Xining, Lanzhou, Nanjing, Shanghai, Hefei, Chengdu, Kunming, and Guangzhou, respectively. Cold temperature was responsible for a higher proportion of deaths than heat. Moderate cold temperature contributed to most of the total health burden. Finally, the cumulative total counts of deaths caused by moderate cold were the largest. Although moderate cold conferred a slightly lower relative risk than extreme cold, it was more common than extreme cold. Taken together, our results show that the effects of moderate cold temperature on health should receive more attention. Furthermore, our findings could help improve the prediction of climate change effects on human health and support the development of response strategies for the changing climate.

Black carbon (BC) may have more adverse effects on human health than other constituents of PM

Visceral leishmaniasis (VL) is an important vector-borne zoonosis caused by Leishmania spp. that has been spreading in China. It has been posing a significant risk to public health in central China due to its recurrence in recent decades. Yet, the spatiotemporal patterns and the driving factors of VL in central China remain unclear at present. The purpose of this study was to analyse spatiotemporal distribution, explore driving factors, and provide novel insight into prevention and control countermeasures of the VL spreading in central China. Based on data of human VL cases from 2006 to 2019 obtained from the Chinese Centres for Disease Control and Prevention (CDC), we depicted the map showing the spatiotemporal distribution of VL in central China. We further explored the driving factors contributing to the spread of VL through the general additive model (GAM) by combining maps of environmental, meteorological, and socioeconomic correlates. Most VL cases were reported in Shaanxi and Shanxi provinces, the number of which has been increasing every year in the last 14 years, from 3 new cases in 2006 to 101 new cases in 2019. The results of GAM revealed that environmental (i.e., changes in grasslands/forests), meteorological (i.e., temperature and relative humidity), and socioeconomic (i.e., population density) factors are significantly associated with the prevalence of VL in central China. Our results provide a better understanding regarding the current situation and the driving factors of VL in central China, assisting in developing the disease prevention and control strategies implemented by public health authorities.

Vector control interventions including long-lasting insecticidal nets and indoor residual spraying are important for malaria control and elimination. And effectiveness of these interventions depends entirely on the high level of susceptibility of malaria vectors to insecticides. However, the insecticide resistance in majority of mosquito vector species across African countries is a serious threat to the success of vector control efforts with the extensive use of insecticides, while no data on insecticide resistance was reported from Sierra Leone in the past decade. In the present study, the polymerase chain reaction was applied for the identification of species of 757 dry adult female Anopheles gambiae mosquitoes reared from larvae collected from four districts in Sierra Leone during May and June 2018. And the mutations of kdr, rdl, ace-1 genes in An. gambiae were detected using SNaPshot and sequencing. As a result, one sample from Western Area Rural district belonged to Anopheles melas, and 748 An. gambiae were identified. Furthermore, the rdl mutations, kdr west mutations and ace-1 mutation were found. The overall frequency was 35.7%, 0.3%, 97.6% and 4.5% in A296G rdl, A296S rdl, kdrW and ace-1, respectively. The frequencies of A296G rdl mutation (P < 0.001), kdrW mutation (P = 0.001) and ace-1 mutation (P < 0.001) were unevenly distributed in four districts, respectively, while no statistical significance was found in A296S rdl mutation (P = 0.868). In addition, multiple resistance patterns were also found. In conclusion, multiple mutations involved in insecticide resistance in An. gambiae populations in Sierra Leone were detected in the kdrW, A296G rdl and ace-1 alleles in the present study. It is necessary to monitor vector susceptibility levels to insecticides used in this country, and update the insecticide resistance monitoring and management strategy.

Sierra Leone is a highly endemic area for malaria, and the implementation of the National Malaria Strategic Plan (2016–2020) has reached its midpoint in 2018. To provide more specific guidance for interventions in the future, a household-based cross-sectional survey was conducted to elucidate the knowledge, awareness and practices regarding malaria and malarial control measures among the general public. Three communities (Grafton, Jui, and Kossoh) in the Western Area Rural District that were in close proximity to Sierra Leone's capital city of Freetown were included. Households were randomly selected and interviewed with a structured questionnaire covering malaria infection, diagnosis, treatment and prevention, as well as knowledge of malaria prevention. As a result, a total of 262 qualified questionnaires were included. The average cost for meals per day is ~30,000 Leones in each household. The rate of awareness, indicated by reporting having heard of malaria, was 98.1% (257/262), and 86.6% (227/262) of the respondents knew that mosquito bites are the main route of transmission. In addition, 80.9% (212/262) of the respondents sought health advice or treatment for the illness, and a similar percentage of respondents had been tested for malaria, mostly with rapid diagnostic tests (RDTs). A high demand for long-lasting insecticidal nets (72.1%) matched the serious shortage (61.8%, 162/262), and of the households that reported a lack of nets, 66 had children younger than 5 years old. In conclusion, public awareness of malaria prevention is high, based on this survey, although there was a limited use of preventive measures in these three communities and the malaria burden was still high. Therefore, the public's knowledge of malaria should be sustained and reinforced, and the distribution and use of malaria prevention measures should be promoted to supprt the achievement of the planned objectives.

Ambient air temperature is a key index that affects human health, including mortality risks of cardiovascular disease (CVD). This study quantitatively investigated CVD mortality burden with respect to various segments across the climatic temperature range. Daily data on average temperature and CVD deaths in nine Chinese cities during 2010–2016 were collected for the study. The association between temperature and city-specific CVD mortality was investigated with a distributed lag nonlinear model across lag 0–21 days for cold temperature and lag 0–2 days for hot temperature, and then pooled the association results in a multivariate meta-analysis to derive the pooled estimates of temperature on CVD mortality at national level. Attributable fractions of CVD mortality to cold- and heat-related (i.e., at temperatures below and above the minimum mortality temperature [MMT]) were calculated. In addition, temperature was further separated at 1 °C intervals of ambient temperature and the attributable fractions of each range were calculated. The results showed that the MMT varied from the 71th to 79th percentiles of temperature in nine Chinese cities, centering at 76th at national level. In total, 16.88% of CVD mortality was attributable to nonoptimal temperature, ranging from 9.73% in Hefei to 24.48% in Nanjing. Cold temperature was responsible for most CVD death burden, with a fraction of 14.62%, compared with 2.26% CVD mortality for heat at overall level. The results of temperature stratification suggested that the highest CVD deaths due to temperature fall within moderate cold. Specifically, the highest attributable fractions were at 7 °C, 7 °C, 8 °C, 4 °C, 5 °C, 4 °C, 4 °C, 5 °C, and 6 °C for Harbin, Changchun, Shenyang, Beijing, Shijiazhuang, Nanjing, Hefei, Shanghai, and Chengdu, respectively. Furthermore, the highest CVD deaths due to temperature were near at the start and end time of heating for five northern cities (Harbin, Changchun, Shenyang, Beijing, and Shijiazhuang). Hence, moderately cold temperature plays a noticeable role in impact mortality. Although moderate cold had a slightly lower relative risk than extreme cold, it occurred on more days than did extreme cold. Finally, the cumulative total counts of CVD deaths caused by moderate cold were the largest. We should pay more attention to the adverse health effects of moderate cold in the future. Additionally, the government and heating departments should slow down the rate of increase (or decrease) temperature at the start (or end) time of heating during moderate time in northern China. The findings have important implications for health promotion and disease prevention strategies of adverse temperatures.

Background The echinococcosis is prevalent in 10 provinces /autonomous region in western and northern China. Epidemiological survey of echinococcosis in China in 2012 showed the average prevalence of four counties in Tibet Autonomous Region (TAR) is 4.23%, much higher than the average prevalence in China (0.24%). It is important to understand the transmission risks and the prevalence of echinococcosis in human and animals in TAR. Methods A stratified and proportionate sampling method was used to select samples in TAR. The selected residents were examined by B-ultrasonography diagnostic, and the faeces of dogs were tested for the canine coproantigen against Echinococcus spp. using enzyme-linked immunosorbent assay. The internal organs of slaughtered domestic animals were examined by visual examination and palpation. The awareness of the prevention and control of echinococcosis among of residents and students was investigated using questionnaire. All data were inputted using double entry in the Epi Info database, with error correction by double-entry comparison, the statistical analysis of all data was processed using SPSS 21.0, and the map was mapped using ArcGIS 10.1, the data was tested by Chi-square test and Cochran-Armitage trend test. Results A total of 80 384 people, 7564 faeces of dogs, and 2103 internal organs of slaughtered domestic animals were examined. The prevalence of echinococcosis in humans in TAR was 1.66%, the positive rate in females (1.92%) was significantly higher than that in males (1.41%), (χ2 = 30.31, P

Background Substantial outbreaks of scrub typhus, coupled with the discovery of this vector-borne disease in new areas, suggest that the disease remains remarkably neglected. The objectives of this study were to map the contemporary and potential transmission risk zones of the disease and to provide novel insights into the health burden imposed by scrub typhus in southern China. Methods Based on the assembled data sets of annual scrub typhus cases and maps of environmental and socioeconomic correlates, a boosted regression tree modeling procedure was used to identify the environmental niche of scrub typhus and to predict the potential infection zones of the disease. Additionally, we estimated the population living in the potential scrub typhus infection areas in southern China. Results Spatiotemporal patterns of the annual scrub typhus cases in southern China between 2007 and 2017 reveal a tremendous, wide spread of scrub typhus. Temperature, relative humidity, elevation, and the normalized difference vegetation index are the main factors that influence the spread of scrub typhus. In southern China, the predicted highest transmission risk areas of scrub typhus are mainly concentrated in several regions, such as Yunnan, Guangxi, Guangdong, Hainan, and Fujian. We estimated that 162 684 million people inhabit the potential infection risk zones in southern China. Conclusions Our results provide a better understanding of the environmental and socioeconomic factors driving scrub typhus spread, and estimate the potential infection risk zones beyond the disease’s current, limited geographical extent, which enhances our capacity to target biosurveillance and help public health authorities develop disease control strategies.

Background The relative contributions of asymptomatic, presymptomatic, and symptomatic transmission of severe acute respiratory syndrome coronavirus 2 have not been clearly measured, although control measures may differ in response to the risk of spread posed by different types of cases. Methods We collected detailed information on transmission events and symptom status based on laboratory-confirmed patient data and contact tracing data from 4 provinces and 1 municipality in China. We estimated the variation in risk of transmission over time and the severity of secondary infections by symptomatic status of the infector. Results There were 393 symptomatic index cases with 3136 close contacts and 185 asymptomatic index cases with 1078 close contacts included in the study. The secondary attack rates among close contacts of symptomatic and asymptomatic index cases were 4.1% (128 of 3136) and 1.1% (12 of 1078), respectively, corresponding to a higher transmission risk from symptomatic cases than from asymptomatic cases (odds ratio, 3.79; 95% confidence interval, 2.06–6.95). Approximately 25% (32 of 128) and 50% (6 of 12) of the infected close contacts were asymptomatic from symptomatic and asymptomatic index cases, respectively, while more than one third (38%) of the infections in the close contacts of symptomatic cases were attributable to exposure to the index cases before symptom onset. Conclusions Asymptomatic and presymptomatic transmissions play an important role in spreading infection, although asymptomatic cases pose a lower risk of transmission than symptomatic cases. Early case detection and effective test-and-trace measures are important to reduce transmission.

Background Sierra Leone is a highly endemic area for malaria, and the implementation of the National Malaria Strategic Plan (2016-2020) has reached its midpoint. To provide more specific guidance for interventions in the future, a household-based cross-sectional survey was conducted to elucidate the knowledge, attitudes and practices regarding malaria and malarial control measures among the general public.Methods Three communities (Grafton, Jui and Kossoh) in the Western Area Rural District that were in close proximity to Sierra Leone’s capital city of Freetown were included. Households were randomly selected and interviewed with a structured questionnaire covering malaria infection, diagnosis, treatment and prevention, as well as knowledge of malaria prevention, in collaboration with the National Malaria Control Program of the Ministry of Health and Sanitation, Sierra Leone. Results A total of 262 qualified questionnaires were included. The average cost for meals per day is approximately 30000 Leones in each household. The rate of awareness, indicated by reporting having heard of malaria, was 98.1% (257/262), and 86.6% (227/262) of the respondents knew that mosquito bites are the main route of transmission. In addition, 80.9% (212/262) of the respondents sought health advice or treatment for the illness, and a similar percentage of respondents had been tested for malaria, mostly with rapid diagnostic tests (RDTs). A hight demand for long-lasting insecticidal nets (72.1%) matched the serious shortage (61.8%, 162/262), and of the households that reported a lack of nets, 66 had children younger than five years old.Conclusion The malaria burden is still high. Although public awareness of malaria prevention is high, based on this survey, there is a shortage of the necessary supplies and a limited use of preventive measures in these three communities. Therefore, the public’s knowledge of malaria should be sustained and reinforced, and the distribution and use of malaria prevention measures should be promoted to supprt the achievement of the planned objectives.

Background Although visceral leishmaniasis (VL), a disease caused by parasites, is controlled in most provinces in China, it is still a serious public health problem and remains fundamentally uncontrolled in some northwest provinces and autonomous regions. The objective of this study is to explore the spatial and temporal characteristics of VL in Sichuan Province, Gansu Province and Xinjiang Uygur Autonomous Region in China from 2004 to 2018 and to identify the risk areas for VL transmission. Methods Spatiotemporal models were applied to explore the spatio-temporal distribution characteristics of VL and the association between VL and meteorological factors in western China from 2004 to 2018. Geographic information of patients from the National Diseases Reporting Information System operated by the Chinese Center for Disease Control and Prevention was defined according to the address code from the surveillance data. Results During our study period, nearly 90% of cases occurred in some counties in three western regions (Sichuan Province, Gansu Province and Xinjiang Uygur Autonomous Region), and a significant spatial clustering pattern was observed. With our spatiotemporal model, the transmission risk, autoregressive risk and epidemic risk of these counties during our study period were also well predicted. The number of VL cases in three regions of western China concentrated on a few of counties. VL in Kashi Prefecture, Xinjiang Uygur Autonomous Region is still serious prevalent, and integrated control measures must be taken in different endemic areas. Conclusions The number of VL cases in three regions of western China concentrated on a few of counties. VL in Kashi Prefecture, Xinjiang Uygur Autonomous Region is still serious prevalent, and integrated control measures must be taken in different endemic areas. Our findings will strengthen the VL control programme in China.

Visceral leishmaniasis (VL) is a neglected disease caused by trypanosomatid protozoa in the genus Leishmania, which is transmitted by phlebotomine sandflies. Although this vector-borne disease has been eliminated in several regions of China during the last century, the reported human VL cases have rebounded in Western and Central China in recent decades. However, understanding of the spatial epidemiology of the disease remains vague, as the spatial risk factors driving the spatial heterogeneity of VL. In this study, we analyzed the spatiotemporal patterns of annual human VL cases in Western and Central China from 2007 to 2017. Based on the related spatial maps, the boosted regression tree (BRT) model was adopted to explore the relationships between VL and spatial correlates as well as predicting both the existing and potential infection risk zones of VL in Western and Central China. The mined links reveal that elevation, minimum temperature, relative humidity, and annual accumulated precipitation make great contributions to the spatial heterogeneity of VL. The maps show that Xinjiang Uygur Autonomous Region, Gansu, western Inner Mongolia Autonomous Region, and Sichuan are predicted to fall in the highest infection risk zones of VL. Approximately 61.60 million resident populations lived in the high-risk regions of VL in Western and Central China. Our results provide a better understanding of how spatial risk factors driving VL spread as well as identifying the potential endemic risk region of VL, thereby enhancing the biosurveillance capacity of public health authorities.

Background The malaria epidemic is high in Sierra Leone, and the implementation of the National Malaria Strategic Plan (2016-2020) has reached its middle stage. In order to guide the interventions more specifically in future, a household-based cross-sectional survey was conducted to understand the public perception of knowledge, attitudes and practices of malaria and its control.Methods Three communities (Grafton, Jui and Kossoh) in Western Area Rural District within close proximity to Sierra Leone’s capital city of Freetown were included. Households were randomly selected and interviewed with a structural questionnaire covering malaria infection, diagnosis, treatment and prevention, as well as the knowledge of malaria prevention, in collaboration with the National Malaria Control Program of the Ministry of Health and Sanitation, Sierra Leone. Results A total of 262 qualified questionnaires were included. The average cost for meals per day is around 30000 Leones in each household. The awareness rate of having heard of malaria is 98.1% (257/262) and knowing mosquito biting as its main route of transmission is 86.6% (227/262) respectively. And 80.9% (212/262) of the respondents sought health advice or treatment for the illness, and similar percentage of them could be tested for malaria, mostly through RDTs. A great demand of long-lasting insecticidal nets (72.1%) was raised to fulfill the high shortage (61.8%, 162/262) in households, and of them there were 66 families having children under five years old.Conclusion Malaria burden is still high. Although public awareness of malaria prevention sounds well in this survey, the fact that the coverage of supplies and the use of preventive measures against malaria is low in households within the three communities. It is suggested that an advanced campaign should be carried out to scale up not only the knowledge on malaria but also the actual coverage and usage of malaria prevention measures, contributing to the achievements of planned objectives.

Scrub typhus, a miteborne rickettsiosis, has emerged in many areas globally. We analyzed the incidence and spatial-temporal distribution of scrub typhus in China during 1952-1989 and 2006-2016 using national disease surveillance data. A total of 133,623 cases and 174 deaths were recorded. The average annual incidence was 0.13 cases/100,000 population during 1952-1989; incidence increased sharply from 0.09/100,000 population in 2006 to 1.60/100,000 population in 2016. The disease, historically endemic to southern China, has expanded to all the provinces across both rural and urban areas. We identified 3 distinct seasonal patterns nationwide; infections peaked in summer in the southwest, summer-autumn in the southeast, and autumn in the middle-east. Persons >40 years of age and in nonfarming occupations had a higher risk for death. The changing epidemiology of scrub typhus in China warrants an enhanced disease control and prevention program.

The effect of temperature on cardiovascular disease (CVD) mortality has been extensively studied. However, it remains largely unknown over whether there is any difference between urban and suburban areas within the same city and how urbanization modifies the relationship between temperature and CVD mortality. In order to examine whether the association between temperature and CVD mortality existed difference in urban and suburban areas, and how urbanization modified this association, we used a distributed lag nonlinear model and a generalized additive model to investigate temperature-related CVD mortality in urban and suburban areas in Beijing, China, from 2006 to 2011. The age, gender, and educational attainment of the population were stratified to explore the modifying effect. We observed that the impacts of heat and cold temperature on CVD mortality were higher in suburban areas than in urban areas. In addition, the elderly and illiterate subjects in suburban areas were more vulnerable to both heat and cold than their counterparts in urban areas. Moreover, higher urbanization levels were significantly associated with districts having lower the excess risks for temperature- CVD mortality. Our findings provide evidence that populations in suburban Beijing have higher risk of temperature-related CVD mortality than those in urban areas. Therefore, greater attention should be paid to vulnerable groups in suburban areas to reduce temperature-related health burden.

Additional file 4: Table S1. Code and name of the investigated counties.

What is already known about this topic? Both alveolar echinococcosis (AE) and cystic echinococcosis are endemic in China, among which alveolar echinococcosis has a very high mortality rate. What is added by this report? The survey results showed the prevalence and scope of AE in China and identified high-risk groups including children, monks, herdsmen and illiterate people. At the same time, all the cases found in the survey (more than 90% of the patients did not go to the hospital for diagnosis and treatment before survey) were promptly diagnosed and treated. What are the implications for public health practice? This study provides information for the development of a plan for AE prevention and control and for the implementation of interventions targeted to high-risk populations.

Visibility has been continuously and stably observed for more than half a century, while particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5) was not introduced to the national monitoring system in China until 2013. It is a scientific issue as to whether visibility can be used as an alternative to assess the health risks of air pollution in periods and areas without pollutant monitoring data. A generalized additive model (GAM) was adopted to estimate the impacts of seasonal changes in visibility on mortality in Beijing, China. Moreover, we estimated the contributions of particulate matter in the health effects of visibility by adjusting for dry extinction coefficient (βdryext) and PM2.5 in the model, respectively. We found that the acute health impacts of visibility varied by season, with the highest risks in winter. For respiratory mortality, the effect estimates per 1 km decrease in visibility were 0.40% (95% CI: 0.17–0.62%), 0.10% (95% CI: −0.14–0.34%), 0.27% (95% CI: 0.09–0.45%), and 0.62% (95% CI: 0.38–0.85%) in spring, summer, autumn, and winter, respectively. For cardiovascular mortality, the effect estimates per 1 km decrease in visibility were 0.20% (95% CI: 0.08–0.31%), 0.16% (95% CI: 0.04–0.27%), 0.25% (95% CI: 0.13–0.37%), and 0.24% (95% CI: 0.13–0.35%) in spring, summer, autumn, and winter, respectively. The seasonal pattern of health impacts related to visibility reflected the seasonal variations in the characteristics of air pollution emission sources and meteorological conditions that are unfavorable for pollutant dispersion. Particulate matter, particularly PM2.5, made significant contributions to the health impacts of visibility. The results indicated that controlling pollutant emissions in winter would be of significant importance to improve air quality and mitigate the health hazard of air pollution in Beijing. Our study also provides further evidence on the feasibility of using visibility to assess the health impacts of particulate matter pollution.

Background Visceral leishmaniasis (VL) is a neglected disease that is spread to humans by the bites of infected female phlebotomine sand flies. Although this vector-borne disease has been eliminated in most parts of China, it still poses a significant public health burden in the Xinjiang Uygur Autonomous Region. Understanding of the spatial epidemiology of the disease remains vague in the local community. In the present study, we investigated the spatiotemporal distribution of VL in the region in order to assess the potential threat of the disease. Methods Based on comprehensive infection records, the spatiotemporal patterns of new cases of VL in the region between 2005 and 2015 were analysed. By combining maps of environmental and socioeconomic correlates, the boosted regression tree (BRT) model was adopted to identify the environmental niche of VL. Results The fitted BRT models were used to map potential infection risk zones of VL in the Xinjiang Uygur Autonomous Region, revealing that the predicted high infection risk zones were mainly concentrated in central and northern Kashgar Prefecture, south of Atushi City bordering Kashgar Prefecture and regions of the northern Bayingolin Mongol Autonomous Prefecture. The final result revealed that approximately 16.64 million people inhabited the predicted potential infection risk areas in the region. Conclusions Our results provide a better understanding of the potential endemic foci of VL in the Xinjiang Uygur Autonomous Region with a 1 km spatial resolution, thereby enhancing our capacity to target the potential risk areas, to develop disease control strategies and to allocate medical supplies.

The resistance of mosquito vectors to insecticides is one of the biological obstacles in the fight against malaria. Understanding of the status and mechanisms underlying the insecticide resistance in Anopheles gambiae species is necessary for success of vector control efforts. The study aimed to determine the molecular forms of An. gambiae from four districts in Sierra Leone during May and June 2018, and the level of N1575Y mutation. The molecular form identification of adult female An. gambiae mosquitoes reared from larvae were carried out using polymerase chain reaction and sequencing. And the N1575Y mutations were detected using SNaPshot and sequencing. As a result, significant differences were found in the distribution of An. gambiae molecular forms among regions (P 0.001). And a total of 638 An. gambiae sensu stricto, 106 An. coluzzi, and 4 hybrid individuals were identified. Moreover, the overall N1575Y mutation frequency was 10.2% with no statistical difference among regions (χ

Echinococcosis, caused by genus Echinococcus, is the most pathogenic zoonotic parasitic disease in the world. In Tibet of the People’s Republic of China, echinococcosis refers principally to two types of severe zoonosis, cystic echinococcosis (CE) and alveolar echinococcosis (AE), which place a serious burden on public health and economy in the local community. However, research on the spatial epidemiology of echinococcosis remains inadequate in Tibet, China. Based on the recorded human echinococcosis data, maps of the spatial distribution of human CE and AE prevalence in Tibet were produced at city level and county level respectively, which show that the prevalence of echinococcosis in northern and western Tibet was much higher than that in other regions. We employ a geographical detector to explore the influencing factors for causing CE and AE while sorting information on the maps of disease prevalence and environment factors (e.g. terrain, population, and yak population). The results of our analysis showed that biological factors have the most impact on the prevalence of echinococcosis, of which the yak population contributes the most for CE, while the dog population contributes the most for AE. In addition, the interaction between various factors, as we found out, might further explain the disease prevalence, which indicated that the echinococcosis prevalence is not simply affected by one single factor, but by multiple factors that are correlated with each other complicatedly. Our results will provide an important reference for the evaluation of the echinococcosis risk, control projects, and prevention programs in Tibet., Author summary Echinococcosis, a worldwide zoonosis caused by genus Echinococcus, is highly endemic in Tibet of China. CE and AE as two main types of Echinococcosis are causing serious health burdens, thereby attracting more attention to public health in Tibet. This work provides detailed geographical information about CE and AE prevalence based on the recorded human echinococcosis data from CDC. A geographical detector was employed to explore the potential environmental factors that influence these diseases and to quantify the specific contribution of each factor as well as discovering the interaction between factors. The results showed that biological factors have the most impact on the prevalence of echinococcosis, of which the yak population contributes most to CE while the dog population makes the most contribution to AE. Besides, the interactive results greatly improved the explanation of the two diseases, indicating that the echinococcosis prevalence is not simply affected by one factor, but by various interrelated factors. Such research can be beneficial to the evaluation, control projects, and prevention programs of the echinococcosis risk in Tibet.

An amendment to this paper has been published and can be accessed via the original article.

We observed significant effects of particulate matter (PM2.5) on cause-specific mortality by applying a time-stratified case-crossover and lag-structure designs in Beijing over a nine-year study period (2005&ndash, 2013). The year-round odds ratio (OR) was 1.005 on the current day with a 10 &mu, g/m3 increase in PM2.5 for all-cause mortality. For cardiovascular mortality and stroke, the ORs were 1.007 and 1.008 on the current day, respectively. Meanwhile, during a lag of six days, the cumulative effects of haze on relative risk of mortality, respiratory mortality and all-cause mortality was in the range of 2~11%. Moreover, we found a significant seasonal pattern in the associations for respiratory mortality: significant associations were observed in spring and fall, while for all-cause mortality, cardiovascular mortality, cardiac and stroke, significant associations were observed in winter. Moreover, increasing temperature would decrease risks of mortalities in winter taking fall as the reference season. We concluded that in summer, temperature acted as a direct enhancer of air pollutants, while in winter and spring, it was an index of the diameter distribution and composition of fine particles.

Although visceral leishmaniasis disease is controlled overall in China, it remains a serious public health problem and remains fundamentally uncontrolled in Jiashi County, Xinjiang Uygur Autonomous Region. During 2005&ndash, 2015, there were two outbreaks in Jiashi County. Assessing the influence of meteorological factors on visceral leishmaniasis incidence is essential for its monitoring and control. In this study, we applied generalized estimating equations to assess the impact of meteorological factors on visceral leishmaniasis risk from 2005 to 2015. We also compared meteorological factors among years with Kruskal&ndash, Wallis test to explore possible reasons behind the two outbreaks that occurred during our study period. We found that temperature and relative humidity had very significant associations with visceral leishmaniasis risk and there were interactions between these factors. Increasing temperature or decreasing relative humidity could increase the risk of visceral leishmaniasis events. The outbreaks investigated might have been related to low relative humidity and high temperatures. Our findings will support the rationale for visceral leishmaniasis control in China.

Ambient air temperature is a key factor affecting human health. Adverse effects of extreme weather on mortality have been well explored and expounded in numerous epidemiological studies. The relationship between moderate temperature and mortality is, however, underexplored. This study quantitatively investigated the temperature-dependent mortality burden in China. Data on daily average temperature and mortality in 15 Chinese cities during 2010-2016 were collected for this study. The association between temperature and city-specific mortality was investigated with a quasi-Poisson regression combined with a distributed lag nonlinear model across lag 0-21 days. The results were then included in a multivariate meta-analysis to derive the pooled estimates of the effect of temperature on mortality at the multi-city level. Mortality fractions attributable to cold and heat (i.e., at temperatures below and above the minimum mortality temperature (MMT)) were calculated. Additionally, temperature ranges were further divided into 1 °C intervals of ambient temperature, and the attributable fractions were calculated for each range. The MMT varied from the 71th to 93th percentiles of temperature in the 15 Chinese cities, centering at the 78th percentile at the multi-city level. In total, 12.65% of non-accidental mortality was attributable to non-optimum temperature, of which cold and hot temperatures corresponded to attributable fractions of 11.38% and 1.27%, respectively. The results of temperature stratifications suggested that moderately cold temperatures provided the highest contribution to mortality caused by temperature. Specifically, the highest attributable fractions were at 7 °C, 7 °C, 8 °C, 8 °C, 4 °C, 4 °C, 5 °C, 7 °C, 7 °C, 4 °C, 5 °C, 5 °C, 6 °C, 11 °C, and 12 °C, for Harbin, Changchun, Shenyang, Urumqi, Beijing, Tianjin, Shijiazhuang, Xining, Lanzhou, Nanjing, Shanghai, Hefei, Chengdu, Kunming, and Guangzhou, respectively. Cold temperature was responsible for a higher proportion of deaths than heat. Moderate cold temperature contributed to most of the total health burden. Finally, the cumulative total counts of deaths caused by moderate cold were the largest. Although moderate cold conferred a slightly lower relative risk than extreme cold, it was more common than extreme cold. Taken together, our results show that the effects of moderate cold temperature on health should receive more attention. Furthermore, our findings could help improve the prediction of climate change effects on human health and support the development of response strategies for the changing climate.

Additional file 1: Table S1. Land cover types. Table S2. Population living in areas with high predicted VL risk within each prefecture-level administrative unit and the top six regions contributing to these populations at risk. Figure S1. The predicted potential VL infection risk zones and the boundaries of the main administrative districts. Figure S2. Uncertainty in the model of predicted VL infection risk. Figure S3. The distribution of VL cases reported from 2016 (a) to 2017 (b).