Presence of three dengue serotypes in Ouagadougou(Burkina Faso):research and public health implications

Background:The significant malaria burden in Africa has often eclipsed other febrile illnesses.Burkina Faso’s first dengue epidemic occurred in 1925 and the most recent in 2013.Yet there is still very little known about dengue prevalence,its vector proliferation,and its poverty and equity impacts.Methods:An exploratory cross-sectional survey was performed from December 2013 to January 2014.Six primary healthcare centers in Ouagadougou were selected based on previously reported presence of Flavivirus.All patients consulting with fever or having had fever within the previous week and with a negative rapid diagnostic test(RDT)for malaria were invited to participate.Sociodemographic data,healthcare use and expenses,mobility,health-related status,and vector control practices were captured using a questionnaire.Blood samples of every eligible subject were obtained through finger pricks during the survey for dengue RDT using SD BIOLINE Dengue Duo(NS1Ag and IgG/IgM)®and to obtain blood spots for reverse transcription polymerase chain reaction(RT-PCR)analysis.In a sample of randomly selected yards and those of patients,potential Aedes breeding sites were found and described.Larvae were collected and brought to the laboratory to monitor the emergence of adults and identify the species.Results:Of the 379 subjects,8.7%(33/379)had positive RDTs for dengue.Following the 2009 WHO classification,38.3%(145/379)had presumptive,probable,or confirmed dengue,based on either clinical symptoms or laboratory testing.Of 60 samples tested by RT-PCR(33 from the positive tests and 27 from the subsample of negatives),15 were positive.The serotypes observed were DENV2,DENV3,and DENV4.Odds of dengue infection in 15-to-20-year-olds and persons over 50 years were 4.0(CI 95%:1.0–15.6)and 7.7(CI 95%:1.6–37.1)times higher,respectively,than in children under five.Average total spending for a dengue episode was 13771 FCFA[1300–67300 FCFA](1$US=478 FCFA).On average,2.6 breeding sites were found per yard.Potential Aedes breeding sites were found near 71.4%(21/28)of patients,but no adult Aedes were found.The most frequently identified potential breeding sites were water storage containers(45.2%).Most specimens collected in yards were Culex(97.9%).Conclusions:The scientific community,public health authorities,and health workers should consider dengue as a possible cause of febrile illness in Burkina Faso.

Priorities and needs for research on urban interventions targeting vector-borne diseases: rapid review of scoping and systematic reviews

This paper highlights the critical importance of evidence on vector-borne diseases(VBD)prevention and control interventions in urban settings when assessing current and future needs,with a view to setting policy priorities that promote inclusive and equitable urban health services.Research should produce knowledge about policies and interventions that are intended to control and prevent VBDs at the population level and to reduce inequities.Such interventions include policy,program,and resource distribution approaches that address the social determinants of health and exert influence at organizational and system levels.

Effective surveillance systems for vectorborne diseases in urban settings and translation of the data into action:a scoping review

Background:Vector-borne diseases(VBDs)continue to represent a global threat,with“old”diseases like malaria,and“emergent”or“re-emergent”ones like Zika,because of an increase in international trade,demographic growth,and rapid urbanization.In this era of globalization,surveillance is a key element in controlling VBDs in urban settings,but surveillance alone cannot solve the problem.A review of experiences is of interest to examine other solution elements.The objectives were to assess the different means of VBD surveillance in urban environments,to evaluate their potential for supporting public health actions,and to describe the tools used for public health actions,the constraints they face,and the research and health action gaps to be filled.Main body:For this scoping review we searched peer-reviewed articles and grey literature published between 2000 and 2016.Various tools were used for data coding and extraction.A quality assessment was done for each study reviewed,and descriptive characteristics and data on implementation process and transferability were analyzed in all studies.After screening 414 full-text articles,we retained a total of 79 articles for review.The main targets of the articles were arboviral diseases(65.8%)and malaria(16.5%).The positive aspects of many studies fit within the framework of integrated vector management.Public awareness is considered a key to successful vector control programs.Advocacy and legislation can reinforce both empowerment and capacity building.These can be achieved by collaboration within the health sector and with other sectors.Research is needed to develop well designed studies and new tools for surveillance and control.Conclusions:The need for surveillance systems in urban settings in both developing and developed countries was highlighted.Countries face the same challenges relating to human,financial,and structural resources.These findings also constitute a wake-up call for governments,academia,funders,and World Health Organization to strengthen control programs and enhance VBD research in urban environments.

Impact of a community-based intervention on Aedes aegypti and its spatial distribution in Ouagadougou,Burkina Faso

Background:Several studies highlighted the impact of community-based interventions whose purpose was to reduce the vectors’breeding sites.These strategies are particularly interesting in low-and-middle-income countries which may find it difficult to sustainably assume the cost of insecticide-based interventions.In this case study we determine the spatial distribution of a community-based intervention for dengue vector control using different entomological indices.The objective was to evaluate locally where the intervention was most effective,using spatial analysis methods that are too often neglected in impact assessments.Methods:Two neighbourhoods,Tampouy and Juvenat in Ouagadougou,Burkina Faso,were chosen among five after a survey was conducted,as part of an assessment related to the burden of dengue.As part of the communitybased intervention conducted in Tampouy between August and early October 2016,an entomological survey was implemented in two phases.The first phase consisted of a baseline entomological characterization of potential breeding sites in the neighbourhood of Tampouy as well as in Juvenat,the control area.This phase was conducted in October 2015 at the end of the rainy season.The mosquito breeding sites were screened in randomly selected houses:206 in Tampouy and 203 in Juvenat.A second phase took place after the intervention,in October 2016.The mosquito breeding sites were investigated in the same yards as during the baseline phase.We performed several entomological analyses to measure site productivity as well as before and after analysis using multilevel linear regression.We used Local Indicators of Spatial Association(LISAs)to analyse spatial concentrations of larvae.Results:After the intervention,it is noted that LISAs at Tampouy reveal few aggregates of all types and the suppression of those existing before the intervention.The analysis therefore reveals that the intervention made it possible to reduce the number of concentration areas of high and low values of pupae.Conclusions:The contribution of spatial methods for assessing community-based intervention are relevant for monitoring at local levels as a complement to epidemiological analyses conducted within neighbourhoods.They are useful,therefore,not only for assessment but also for establishing interventions.This study shows that spatial analyses also have their place in population health intervention research.