Ecological and behavioural risk factors of scrub typhus in central Vietnam:a case-control study

Background The risk factors for scrub typhus in Vietnam remain unknown.Scrub typhus caused by Orientia tsutsugamushi often presents as an undifferentiated febrile illness and remains under appreciated due to the limited availability of diagnostic tests.This tropical rickettsial illness is increasingly recognized as an important cause of non-malaria acute undifferentiated fever in Asia.This study aimed to investigate behavioural and ecological related risk factors of scrub typhus to prevent this potentially life-threatening disease in Vietnam.Methods We conducted a clinical hospital-based active surveillance study,and a retrospective residence-enrolment date-age-matched case–control study in Khanh Hoa province,Vietnam,from August 2018 to March 2020.Clinical examinations,polymerase chain reaction and enzyme-linked immunosorbent assay IgM tests were applied to define cases and controls.All enrolled participants filled out a questionnaire including demographic socio-economic status,personal behaviors/protective equipment,habitat connections,land use,and possible exposure to the vector.Multivariable conditional logistic regression was used to define the scrub typhus associated risk factors.Results We identified 44 confirmed cases and matched them with 152 controls.Among cases and controls,the largest age group was the 41–50 years old and males accounted for 61.4%and 42.8%,respectively.There were similarities in demographic characteristics between the two groups,with the exception of occupation.Several factors were significantly associated with acquisition of scrub typhus,including sitting/laying directly on household floor[adjusted OR(aOR)=4.9,95%CI:1.6–15.1,P=0.006],household with poor sanitation/conditions(aOR=7.9,95%CI:1.9–32.9,P=0.005),workplace environment with risk(aOR=3.0,95%CI:1.2–7.6,P=0.020),always observing mice around home(aOR=3.7,95%CI:1.4–9.9,P=0.008),and use of personal protective equipment in the field(aOR=0.4,95%CI:0.1–1.1,P=0.076).Conclusions Ecological and household hygiene-related factors were more associated with scrub typhus infection,than individual-level exposure activities in the hyper-endemic area.These findings support local education and allow people to protect themselves from scrub typhus,especially in areas with limitations in diagnostic capacity.

The impact of pastoralist mobility on tuberculosis control in Ethiopia:a systematic review and meta-synthesis

Background:Directly observed treatment,short-course(DOTS)is the current mainstay to control tuberculosis(TB)worldwide.Context-specific adaptations of DOTS have impending implications in the fight against TB.In Ethiopia,there is a national TB control programme with the goal to eliminate TB,but uneven distribution across lifestyle gradients remains a challenge.Notably,the mobile pastoralist communities in the country are disproportionately left uncovered.The aim of this study was to summarize the evidence base from published literature to guide TB control strategy for mobile pastoralist communities in Ethiopia.Main text:We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)guidelines and systematically reviewed articles in seven electronic databases:Excerptra Medical Database,African Journal Online,PubMed,Google Scholar,Centre for Agriculture and Bioscience International Direct,Cochrane Library and Web of Science.The databases were searched from inception to December 31,2018,with no language restriction.We screened 692 items of which 19 met our inclusion criteria.Using a meta-ethnographic method,we identified six themes:(i)pastoralism in Ethiopia;(ii)pastoralists’livelihood profile;(iii)pastoralists’service utilisation;(iv)pastoralists’knowledge and awareness on TB control services;(v)challenges of TB control in pastoral settings;and(vi)equity disparities affecting pastoralists.Our interpretation triangulates the results across all included studies and shows that TB control activities observed in pastoralist regions of Ethiopia are far fewer than elsewhere in the country.Conclusions:This systematic review and meta-synthesis shows that TB control in Ethiopia does not align well with the pastoralist lifestyle.Inaccessibility and lack of acceptability of TB care are the key bottlenecks to pastoralist TB service provision.Targeting these two parameters holds promise to enhance effectiveness of an intervention.

GPS-based fine-scale mapping surveys for schistosomiasis assessment: a practical introduction and documentation of field implementation

Background Fine-scale mapping of schistosomiasis to guide micro-targeting of interventions will gain importance in elimination settings,where the heterogeneity of transmission is often pronounced.Novel mobile applications offer new opportunities for disease mapping.We provide a practical introduction and documentation of the strengths and shortcomings of GPS-based household identification and participant recruitment using tablet-based applications for fine-scale schistosomiasis mapping at sub-district level in a remote area in Pemba,Tanzania.Methods A community-based household survey for urogenital schistosomiasis assessment was conducted from November 2020 until February 2021 in 20 small administrative areas in Pemba.For the survey,1400 housing structures were prospectively and randomly selected from shapefile data.To identify pre-selected structures and collect survey-related data,field enumerators searched for the houses’geolocation using the mobile applications Open Data Kit(ODK)and MAPS.ME.The number of inhabited and uninhabited structures,the median distance between the pre-selected and recorded locations,and the dropout rates due to non-participation or non-submission of urine samples of sufficient volume for schistosomiasis testing was assessed.Results Among the 1400 randomly selected housing structures,1396(99.7%)were identified by the enumerators.The median distance between the pre-selected and recorded structures was 5.4 m.A total of 1098(78.7%)were residential houses.Among them,99(9.0%)were dropped due to continuous absence of residents and 40(3.6%)households refused to participate.In 797(83.1%)among the 959 participating households,all eligible household members or all but one provided a urine sample of sufficient volume.Conclusions The fine-scale mapping approach using a combination of ODK and an offline navigation application installed on tablet computers allows a very precise identification of housing structures.Dropouts due to non-residential housing structures,absence,non-participation and lack of urine need to be considered in survey designs.Our findings can guide the planning and implementation of future household-based mapping or longitudinal surveys and thus support micro-targeting and follow-up of interventions for schistosomiasis control and elimination in remote areas.

Performance of a real-time PCR approach for diagnosing Schistosoma haematobium infections of different intensity in urine samples from Zanzibar

Background:Efforts to control and eliminate schistosomiasis have accelerated over the past decade.As parasite burden,associated morbidity and egg excretion decrease,diagnosis with standard parasitological methods becomes harder.We assessed the robustness and performance of a real-time PCR(qPCR)approach in comparison with urine filtration microscopy and reagent strip testing for the diagnosis of Schistosoma haematobium infections of different intensities.Methods:The robustness of DNA isolation and qPCR was validated in eight laboratories from Europe and Africa.Subsequently,792 urine samples collected during cross-sectional surveys of the Zanzibar Elimination of Schistosomiasis Transmission(ZEST)project in 2012-2017 were examined with qPCR in 2018.Diagnostic sensitivity of the qPCR was calculated at different infection intensity categories,using urine filtration microscopy as reference test.Spearman's rank correlation between Ct-values and S.haematobium egg counts was assessed and Ct-value percentiles for infection intensity categories determined.Results:S.haematobium Dra1 DNA-positive samples were identified correctly in all eight laboratories.Examination of urine samples from Zanzibar revealed Dra1 DNA in 26.8%(212/792)by qPCR,S.haematobium eggs in 13.3%(105/792)by urine filtration,and microhaematuria in 13.8%(109/792)by reagent strips.Sensitivity of the qPCR increased with augmenting egg counts:80.6%(29/36)for counts between 1 and 4 eggs,83.3%(15/18)for counts between 5 and 9 eggs,100%(23/23)for counts between 10 and 49 eggs,and 96.4%(27/28)for counts of 50+eggs.There was a significant negative correlation between Ct-values and egg counts(Spearman's rho=-0.49,P<0.001).Seventy-five percent of the Ct-values were≥33 in the egg-negative category,<31 in the light intensity category,and<24 in the heavy intensity category.Conclusions:While the sensitiivity of the qPCR was^80%for very light intensity infections(egg counts<10),in general,the Dra1 based qPCR assay detected twice as many S.haematobium infections compared with classical parasitological tests.The qPCR is hence a sensitive,urine-based approach for S.haernatcbium diagnosis that can be used for impact assessment of schistosomiasis elimination programmes,individual diagnosis,and in improved format also for verification and certification of elimination.Trial registration:ISRCTN,ISRCTN48837681.Registered 05 September 2012-Retrospectively registered.

Effectiveness of a home-environmental intervention package and an early child development intervention on child health and development in high-altitude rural communities in the Peruvian Andes: a cluster-randomised controlled trial

Background: Unsafe drinking water,poor sanitation and hygiene,exposure to household air pollution and low cognitive and socio-emotional stimulation are risk factors affecting children in low-and middle-income countries.We implemented an integrated home-environmental intervention package(IHIP),comprising a kitchen sink,hygiene education and a certified improved biomass cookstove,and an early child development(ECD)programme to improve children´s health and developmental outcomes in the rural high-altitude Andes of Peru.Methods: We conducted a one-year cluster-randomised controlled trial among 317 children<36 months divided into 4 arms(IHIP+ECD,IHIP,ECD,and Control)and 40 clusters(10 clusters per arm).ECD status(socio-emotional,fine and gross motor,communication,cognitive skills,and an overall performance)measured with the Peruvian Infant Development Scale and the occurrence of self-reported child diarrhoea from caretakers were primary outcomes.Secondary outcomes included the occurrence of acute respiratory infections and the presence of thermo-tolerant faecal bacteria in drinking water.The trial was powered to compare each intervention against its control arm but it did not allow pairwise comparisons among the four arms.Primary analysis followed the intention-to-treat principle.For the statistical analysis,we employed generalised estimating equation models with robust standard errors and an independent correlation structure.Results: We obtained ECD information from 101 children who received the ECD intervention(individually and combined with IHIP)and 102 controls.Children who received the ECD intervention performed better in all the domains compared to controls.We found differences in the overall performance(64 vs.39%,odd ratio(OR):2.8;95%confidence interval(CI):1.6–4.9)and the cognitive domain(62 vs 46%,OR:1.9;95%CI:1.1–3.5).Data analysis of child morbidity included 154 children who received the IHIP intervention(individually and combined with ECD)and 156 controls.We recorded 110,666 child-days of information on diarrhoea morbidity and observed 1.3 mean episodes per child-year in the children who received the IHIP intervention and 1.1 episodes in the controls.This corresponded to an incidence risk ratio of 1.2(95%CI:0.8–1.7).Conclusions: Child stimulation improved developmental status in children,but there was no health benefit associated with the home-environmental intervention.Limited year-round access to running water at home and the possible contamination of drinking water after boiling were two potential factors linked to the lack of effect of the home-environmental intervention.Potential interactions between ECD and home-environmental interventions need to be further investigated.