Support for research towards understanding the population health vulnerabilities to vector-borne diseases:increasing resilience under climate change conditions in Africa

Background:Diseases transmitted to humans by vectors account for 17%of all infectious diseases and remain significant public health problems.Through the years,great strides have been taken towards combatting vectorborne diseases(VBDs),most notably through large scale and coordinated control programmes,which have contributed to the decline of the global mortality attributed to VBDs.However,with environmental changes,including climate change,the impact on VBDs is anticipated to be significant,in terms of VBD-related hazards,vulnerabilities and exposure.While there is growing awareness on the vulnerability of the African continent to VBDs in the context of climate change,there is still a paucity of research being undertaken in this area,and impeding the formulation of evidence-based health policy change.Main body:One way in which the gap in knowledge and evidence can be filled is for donor institutions to support research in this area.The collaboration between the WHO Special Programme for Research and Training in Tropical Diseases(TDR)and the International Centre for Research and Development(IDRC)builds on more than 10 years of partnership in research capacity-building in the field of tropical diseases.From this partnership was born yet another research initiative on VBDs and the impact of climate change in the Sahel and sub-Saharan Africa.This paper lists the projects supported under this research initiative and provides a brief on some of the policy and good practice recommendations emerging from the ongoing implementation of the research projects.Conclusion:Data generated from the research initiative are expected to be uptaken by stakeholders(including communities,policy makers,public health practitioners and other relevant partners)to contribute to a better understanding of the impacts of social,environmental and climate change on VBDs(i.e.the nature of the hazard,vulnerabilities,exposure),and improve the ability of African countries to adapt to and reduce the effects of these changes in ways that benefit their most vulnerable populations.

Supporting and strengthening research on urban health interventions for the prevention and control of vector-borne and other infectious diseases of poverty:scoping reviews and research gap analysis

Background:More than half of the world’s population currently lives in urban settlements that grow both in size and number.By 2050,approximately 70%of the global population will be living in urban conglomerations,mainly in low-and middle-income countries.Mobility,poverty,different layers of inequalities as well as climate variability and change are some of the social and environmental factors that influence the exposure of human populations in urban settings to vector-borne diseases,which pose eminent public health threats.Accurate,consistent,and evidencebased interventions for prevention and control of vector-borne and other infectious diseases of poverty in urban settings are needed to implement innovative and cost-effective public policy and to promote inclusive and equitable urban health services.Main body:While there is growing awareness of vector-borne diseases epidemiology at the urban level,there is still a paucity of research and action being undertaken in this area,hindering evidence-based public health policy decisions and practice and strategies for active community engagement.This paper describes the collaboration and partnership of the Special Programme for Research and Training in Tropical Diseases(TDR)hosted by the World Health Organization(WHO)and the“VEctor boRne DiseAses Scoping reviews”(VERDAS)Research Consortium as they joined efforts in response to filling this gap in knowledge and evidence by supporting the development of a series of scoping reviews that highlight priority research gaps and policy implications to address vector-borne and other infectious diseases at the urban level.Conclusions:The set of scoping reviews proposed in this special issue presents a critical analysis of the state-of-the-art of research on urban health interventions for the prevention and control of vector-borne and other infectious diseases of poverty.The authors of the 6 reviews highlighted severe gaps in knowledge and identified organizational and theoretical limitations that need to be urgently tackled to improve cities preparedness and vector control response.The more pressing need at present is to ensure that more implementation research on vector-borne diseases in urban settings is conducted,addressing policy and practice implications and calling for more political commitment and social mobilization through adequate citizen engagement strategies.

Establishing research priorities in prevention and control of vector-borne diseases in urban areas:a collaborative process

Background:In 2015,following a call for proposals from the Special Programme for Research and Training in Tropical Diseases(TDR),six scoping reviews on the prevention and control of vector-borne diseases in urban areas were conducted.Those reviews provided a clear picture of the available knowledge and highlighted knowledge gaps,as well as needs and opportunities for future research.Based on the research findings of the scoping reviews,a concept mapping exercise was undertaken to produce a list of priority research needs to be addressed.Methods:Members of the six research teams responsible for the“VEctor boRne DiseAses Scoping reviews”(VERDAS)consortium’s scoping reviews met for 2 days with decision-makers from Colombia,Brazil,Peru,Pan-American Health Organization,and World Health Organization.A total of 11 researchers and seven decision-makers(from ministries of health,city and regional vector control departments,and vector control programs)completed the concept mapping,answering the question:“In view of the knowledge synthesis and your own expertise,what do we still need to know about vector-borne diseases and other infectious diseases of poverty in urban areas?”Participants rated each statement on two scales from 1 to 5,one relative to‘priority’and the other to‘policy relevance’,and grouped statements into clusters based on their own individual criteria and expertise.Results:The final map consisted of 12 clusters.Participants considered those entitled“Equity”,“Technology”,and“Surveillance”to have the highest priority.The cluster considered the most important concerns equity issues,confirming that these issues are rarely addressed in research on vector-borne diseases.On the other hand,the“Population mobility”and“Collaboration”clusters were considered to be the lowest priority but remained identified by participants as research priorities.The average policy relevance scores for each of the 12 clusters were roughly the same as the priority scores for all clusters.Some issues were not addressed during the brain-storming.This is the case for governance and for access and quality of care.Conclusions:Based on this work,and adopting a participatory approach,the concept mapping exercise conducted collaboratively with researchers from these teams and high-level decision-makers identified research themes for which studies should be carried out as a priority.

Levels of insecticide resistance to deltamethrin,malathion,and temephos,and associated mechanisms in Aedes aegypti mosquitoes from the Guadeloupe and Saint Martin islands(French West Indies)

Background:In the Guadeloupe and Saint Martin islands,Aedes aegypti mosquitoes are the only recognized vectors of dengue,chikungunya,and Zika viruses.For around 40 years,malathion was used as a mosquito adulticide and temephos as a larvicide.Since the European Union banned the use of these two insecticide molecules in the first decade of the 21st century,deltamethrin and Bacillus thuringiensis var.israelensis are the remaining adulticide and larvicide,respectively,used in Guadeloupe.In order to improve the management of vector control activities in Guadeloupe and Saint Martin,we investigated Ae.aegypti resistance to and mechanisms associated with deltamethrin,malathion,and temephos.Methods:Ae.aegypti mosquitoes were collected from six different localities of Guadeloupe and Saint Martin.Larvae were used for malathion and temephos bioassays,and adult mosquitoes for deltamethrin bioassays,following World Health Organization recommendations.Knockdown resistance(Kdr)genotyping for V1016I and F1534C mutations,and expression levels of eight enzymes involved in detoxification mechanisms were examined in comparison with the susceptible reference Bora Bora strain.Results:Resistance ratios(RR50)calculated for Ae.aegypti larvae showed high resistance levels to temephos(from 8.9 to 33.1-fold)and low resistance levels to malathion(from 1.7 to 4.4-fold).Adult females displayed moderate resistance levels to deltamethrin regarding the time necessary to affect 50%of individuals,varying from 8.0 to 28.1-fold.Molecular investigations on adult mosquitoes showed high resistant allele frequencies for V1016I and F1534C(from 85 to 96%and from 90 to 98%,respectively),as well as an overexpression of the glutathione S-transferase gene,GSTe2,the carboxylesterase CCEae3a,and the cytochrome genes 014614,CYP6BB2,CYP6M11,and CYP9J23.Conclusions:Ae.aegypti populations from Guadeloupe and Saint Martin exhibit multiple resistance to organophosphates(temephos and malathion),and pyrethroids(deltamethrin).The mechanisms associated with these resistance patterns show strong frequencies of F1534C and V1016I Kdr mutations,and an over-expression of CCEae3a,GSTe2,and four cytochrome P450 genes(014614,CYP9J23,CYP6M11,CYP6BB2).These results will form the baseline for a deeper understanding of the insecticide resistance levels and associated mechanisms of Ae.aegypti populations and will be used to improve vector control strategies in Guadeloupe and Saint Martin.