Scoping review on vector-borne diseases in urban areas: transmission dynamics, vectorial capacity and co-infection

Insecticide resistance in Aedes aegypti: An impact from human urbanization?

In the city of Magelang, Indonesia, the distribution of Dengue Haemorhagic Fever (DHF) cases tend to be clustered, ever changing along with human urbanization from 2014 to 2017. Although DHF cases have been less reported in the city of Magelang for the past 5 years, vector control measures by using insecticide space spraying, particularly permethrin, have been continuously performed. Current study aimed to detect kdr mutations associated with pyrethroid resistance in Ae. aegypti and to study possible association between insecticide resistance and DHF case distribution related to human urbanization. The study was a cross sectional study conducted in 3 sub-districts in the city of Magelang, Central Java, Indonesia. Eggs of Ae. aegypti collected from 195 sample households were reared and were tested for resistance to pyrethroids by using PCR. Primers AaSCF1 and AaSCR4, and primers AaSCF7 and AaSCR7 were used in detecting presence of mutation in VGSC IIS6 and IIIS6 gene, respectively. Fragments of amplified DNA were sequenced and were analyzed. Spatio-temporal using Standard Deviational Ellipse (SDE) was performed to obtain mapping of DHF case distribution trends. The total number of DHF case was 380 cases, with the most cases (158) occurred in 2015 and the least cases (66) reported in 2017. DHF case distribution was grouped into several clusters. SDE calculation demonstrated movement of DHF case in the direction to principal arterial road, suggesting link to urbanization. Gene sequencing demonstrated VGSC IIS6 gene mutation (S989P and V1016G) in Ae. aegypti collected from study areas, indicating resistance to permethrin. VGSC IIIS6 gene mutation was not found. Current study concluded that multiple kdr mutations associated with resistance to pyrethroid was detected in Ae. aegypti, and that human urbanization may have a role in the development of such resistance.

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.

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 evidence-based 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.