The landscape epidemiology of echinococcoses

Echinococcoses are parasitic diseases of major public health importance globally.Human infection results in chronic disease with poor prognosis and serious medical,social and economic consequences for vulnerable populations.According to recent estimates,the geographical distribution of Echinococcus spp.infections is expanding and becoming an emerging and re-emerging problem in several regions of the world.Echinococcosis endemicity is geographically heterogeneous and over time it may be affected by global environmental change.Therefore,landscape epidemiology offers a unique opportunity to quantify and predict the ecological risk of infection at multiple spatial and temporal scales.Here,we review the most relevant environmental sources of spatial variation in human echinococcosis risk,and describe the potential applications of landscape epidemiological studies to characterise the current patterns of parasite transmission across natural and human-altered landscapes.We advocate future work promoting the use of this approach as a support tool for decision-making that facilitates the design,implementation and monitoring of spatially targeted interventions to reduce the burden of human echinococcoses in disease-endemic areas.

Real-time PCR diagnosis of Schistosoma japonicum in low transmission areas of China

Background:Schistosomiasis in the People’s Republic of China(PRC)can be traced back to antiquity.In the past 60 years,the Chinese government has made great efforts to control this persistent disease with elimination slated by 2020 through the implementation of a comprehensive control strategy.This strategy aims to reduce the role of bovines and humans as sources of infection as a pre-requisite for elimination through transmission interruption.The goal of elimination will be achievable only by the implementation of a sustainable surveillance and control system,with sensitive diagnosis a key feature so that the true disease burden is not underestimated.Currently used diagnostics lack the necessary sensitivity to accurately determine the prevalence of Schistosoma japonicum infection in areas with low infection intensities.It is of critical importance to find and treat people and to identify animals with low-level infections if the National Control Programme for China is to achieve schistosomiasis elimination.Methods:We evaluated a real-time polymerase chain reaction(qPCR)assay using 633 human stool samples collected from five villages in Hunan,Anhui,Hubei,and Jiangxi provinces,and 182 bovine(70 cattle and 112 buffalo)stool samples obtained from four villages in Hunan,Anhui,and Jiangxi provinces in the PRC.All stool samples were subjected to the miracidium hatching test(MHT,a diagnostic procedure used in the National Schistosomiasis Control Programme)and the qPCR assay.Samples positive by MHT were subjected to either the Kato-Katz technique for humans,or the formalin-ethyl acetate sedimentation-digestion(FEA-SD)procedure for bovines,to determine infection intensities.Results:The qPCR assay exhibited a high level of sensitivity in the detection of S.japonicum infections.With both the human and bovine samples,a significantly higher prevalence was determined using the qPCR assay(11.06%humans,24.73%bovines)than with the MHT(0.93%humans,7.69%bovines).The animal contamination index(calculated using data obtained with the qPCR technique)for all positive bovines was 27618000 eggs per day,indicating a considerable amount of environmental egg contamination that would be underestimated using less sensitive diagnostic procedures.Conclusions:The qPCR assay we have evaluated will be applicable as a future field diagnostic and surveillance tool in low-transmission zones where schistosomiasis elimination is targeted and for monitoring post-intervention areas to verify that elimination has been maintained.

Estimating the prevalence of Echinococcus in domestic dogs in highly endemic for echinococcosis

Background:Cystic echinococcosis(CE)and alveolar echinococcosis(AE)are highly endemic in Xiji County of Ningxia Hui Autonomous Region(NHAR)in China where the control campaign based on dog de-worming with praziquantel has been undertaken over preceding decades.This study is to determine the current prevalence of Echinococcus granulosus and E.multilocularis in domestic dogs and monitor the echinococcosis transmission dynamics.Methods:Study villages were selected using landscape patterns(Geographic Information System,GIS)for Echinococcus transmission“hot spots”,combined with hospital records identifying risk areas for AE and CE.A survey of 750 domestic dogs,including copro-sampling and owner questionnaires,from 25 selected villages,was undertaken in 2012.A copro-multiplex PCR assay was used for the specific diagnosis of E.granulosus and E.multilocularis in the dogs.Data analysis,using IBM SPSS Statistics,was undertaken,to compare the prevalence of the two Echinococcus spp.in dogs between four geographical areas of Xiji by theχ^(2)test.Univariate analysis of the combinations of outcomes from the questionnaire and copro-PCR assay data was carried out to determine the significant risk factors for dog infection.Results:The highest de-worming rate of 84.0%was found in the northwest area of Xiji County,and significant differences(P<0.05)in the de-worming rates among dogs from the four geographical areas of Xiji were detected.The highest prevalence(19.7%,59/300)of E.multilocularis occurred in northwest Xiji,though the highest prevalence(18.1%,38/210)of E.granulosus occurred in southwest Xiji.There was no significant difference(P>0.05)in the prevalence of E.granulosus in dogs from the northwest,southwest,northeast,and southeast of Xiji,but there were significant differences(P<0.05)between dogs infected with E.multilocularis from the four areas.None of the other independent variables was statistically significant.Conclusions:The results from this study indicate a high prevalence of both E.granulosus and E.muiltilocularis in dogs in Xiji County,NHAR.Transmission of E.multilocularis was more impacted by geographical risk-factors in Xiji County than that of E.granulosus.Dogs have the potential to maintain the transmission of both species of Echinococcus within local Xiji communities,and the current praziquantel dosing of dogs appears to be ineffective or poorly implemented in this area.

Clinical predictors of severe dengue:a systematic review and meta-analysis

Background:Severe dengue is a life-threatening complication;rapid identifcation of these cases,followed by adequate management is crucial to improve the clinical prognosis.Therefore,this study aimed to identify risk factors and predictors of severe dengue.Methods:A literature search for studies reporting risk factors of severe dengue among individuals with dengue virus infection was conducted in PubMed,Scopus and Web of Science database from inception to December 31,2020.Pooled odds ratios(ORs)for patients’demographic characteristics,co-morbidities,and warning signs were estimated using an inverse variance heterogeneity model.Results:We included 143 articles in the meta-analysis from a total of 13090 articles retrieved from the literature search.The risk factors of severe dengue were:being a child[OR=1.96;95%confdence interval(CI):1.22–3.13],secondary infection(OR=3.23;95%CI:2.28–4.57),and patients with pre-existing diabetes(OR=2.88;95%CI:1.72–4.81)and renal disease(OR=4.54;95%CI:1.55–13.31).Warning signs strongly associated with severe disease were increased haematocrit with a concurrent decrease in platelet count(OR=5.13;95%CI:1.61–16.34),abdominal pain(OR=2.00;95%CI:1.49–2.68),lethargy(OR=2.73;95%CI:1.05–7.10),vomiting(OR=1.80;95%CI:1.43–2.26),hepa‑tomegaly(OR=5.92;95%CI:3.29–10.66),ascites(OR=6.30;95%CI:3.75–10.60),pleural efusion(OR=5.72;95%CI:3.24–10.10)and melena(OR=4.05;95%CI:1.64–10.00).Conclusions:Our meta-analysis identifed children,secondary infection,diabetes and renal disease(s)as important predictors of severe dengue.Our fnding also supports the predictive ability of the WHO warning signs to iden‑tify severe dengue.These fndings are useful for clinicians to identify severe dengue for management and timely interventions.

The control of soil-transmitted helminthiases in the Philippines: the story continues

Background:Soil-transmitted helminth(STH)infections have long been an important public health concern in the Philippines.In this review,we describe the current status of STH infections there and highlight the control efforts undertaken to reduce STH burden.Main text:A nationwide STH mass drug administration(MDA)programme was started in 2006 but the overall STH prevalence remains stubbornly high across the Philippines,rangi ng from 24.9%to 97.4%.

The COVID-19 vaccination campaign in Bhutan: strategy and enablers

Bhutan has reported a total of 2596 COVID-19 cases and three deaths as of September 15,2021.With support from India,the United States,Denmark,the People’s Republic of China,Croatia and other countries,Bhutan was able to conduct two rounds of nationwide vaccination campaign.While many countries struggle to overcome vaccine refusal or hesitancy due to complacency,a lack of trust,inconvenience and fear,escalated in some countries by anti-vaccine groups,Bhutan managed to inoculate more than 95%of its eligible populations in two rounds of vaccination campaign.Enabling factors of this successful vaccination campaign were strong national leadership,a well-coordinated national preparedness plan,and high acceptability of vaccine due to effective mass communication and social engagement led by religious figures,volunteers and local leaders.In this short report,we described the national strategic plan and enabling factors that led to the success of this historical vaccination campaign.

Health-education to prevent COVID-19 in schoolchildren: a call to action

Background:There is currently considerable international debate around school closures/openings and the role of children in the transmission of coronavirus disease 2019(COVID-19).Whilst evidence suggests that children are not impacted by COVID-19 as severely as adults,little is still known about their transmission potential,and with a lot of asymptomatic cases they may be silent transmitters(i.e.infectious without showing clinical signs of disease),albeit at a lower level than adults.In relation to this,it is somewhat concerning that in many countries children are cared for,or are often in close contact with,older individuals such as grandparents—the age group most at risk of acquiring serious respiratory complications resulting in death.Main text:We emphasise that in the absence of a vaccine or an effective therapeutic drug,preventive measures such as good hygiene practices—hand washing,cough etiquette,disinfection of surfaces and social distancing represent the major(in fact only)weapons that we have against COVID-19.Accordingly,we stress that there is a pressing need to develop specific COVID-19 prevention messages for schoolchildren.Conclusion:An entertainment education intervention for schoolchildren systematically implemented in schools would be highly effective and fill this need.With such measures in place there would be greater confidence around the opening of schools.

Repeated praziquantel treatment and Opisthorchis viverrini infection:a population-based cross-sectional study in northeast Thailand

Background:Opisthorchis viverrini infection is highly prevalent in northeast Thailand.This liver fluke is classified as a carcinogen due to its causal links with cholangiocarcinoma(CCA)development.Although treatment with praziquantel(PZQ)effectively cures O.viverrini infection,the prevalence remains high due to the traditional consumption of raw fish.Therefore,re-infection is common in the endemic community,leading to severe hepatobiliary morbidities including the fatal CCA.In this study,we evaluate the association between the frequency of previous PZQ treatment and current O.viverrini infections among Thai adults living in the endemic area of northeast Thailand.Methods:This study includes all participants who were screened for O.viverrini infection in the Cholangiocarcinoma Screening and Care Program(CASCAP),northeast Thailand.History of PZQ treatment was recorded using a health questionnaire.O.viverrini infections were diagnosed using urine antigen detection.Associations between PZQ and O.viverrini were determined by adjusted odds ratio(aOR)and 95%confidence interval(CI)using multiple logistic regression.Results:Among participants,27.7%had previously been treated once with PZQ,8.2%twice,2.8%three times,and 3.5%more than three times.Current O.viverrini prevalence was 17%(n=524).Compared with participants who never used PZQ,the aOR for infection among those who used the drug once was 1.09(95%CI:0.88-1.37),twice was 1.19(95%CI:0.85-1.68),three times was 1.28(95%C/:0.74-2.21),and more than three times was 1.86(95%C/:1.18-2.93;P=0.007).Conclusions:The population with a frequent history of PZQ use and still continued raw fish consumption showed high levels of repeated reinfection with O.viverrini.They were infected,treated and re-infected repeatedly.These findings suggest that certain participants continue raw fish consumption even after previous infection.This is a particular problem in highly endemic areas for O.viverrni and increases the risk of CCA.

Correction to:Repeated praziquantel treatment and Opisthorchis viverrini infection:a population-based crosssectional study in northeast Thailand

In the original publication of this article[1],there is an error in the section of‘Ethics approval and consent to participate’at the end of the article,the correct Ethics reference number should be HE551404 rather than HE591067.