[Recurrence of dengue epidemics in Burkina Faso: Community preference for an intervention to prevent the disease]

KIR2DL2, KIR2DL5A and KIR2DL5B Genes Induce Susceptibility to Dengue Virus Infection, while KIR3DL3 and KIR2DS5 Confer Protection

BACKGROUND AND OBJECTIVES

Dengue fever (DF), an emerging and re-emerging viral disease, is a major public health problem. The aim of this study was to investigate the influence of KIRs genes polymorphism and KIRs genotypes in susceptibility to dengue virus infection and disease severity in a population from Burkina Faso through a case-control study.

METHODS

KIRs genes determination was performed using PCR-SSP in 50 patients infected by dengue virus (DENV) and 54 Healthy controls (HC) subjects who had never been infected.

RESULTS

Data analysis showed significant association between frequencies of three KIR genes and dengue virus infection (DF): KIR2DL2 (OR: 7.32; IC: 2.87-18.65; P < 0.001); KIR2DL5A (OR: 15.00, IC: 5.68-39.59; P < 0.001) and KIR2DL5B (OR: 11.43; IC: 4.42-29; P < 0.001). While, KIR3DL3 (OR: 0.13, IC: 0.052-0.32; P < 0.001) and KIR2DS5 (OR: 0.12; IC: 0.04-0.30; P < 0.001) were associated with protection against DF. KIR2DL4 (OR: 9.75; IC95%: 1.33-70.97; p: 0.03) and KIRD3DL1 (OR: 12.00; IC95%: 1.60-90.13; p: 0.02) were associated with an increased risk in the development of secondary dengue infection (SDI).

CONCLUSION

The results suggest a contribution of KIR2DL2, KIR2DL5A, and KIR2DL5B genes in the susceptibility of DF development. In contrast, KIR3DL3 and KIR2DS5 were associated with protection against DF development by enhancing both innate and acquired immune responses.

Analyzing implementation of public health interventions : a need for rigor, and the challenges of stakeholder involvement

OBJECTIVES

This article shows how conceptual models can help to develop and evaluate public health interventions. It also reports on the challenges of getting stakeholders involved.

METHOD

The analysis is based on the reflexive approach applied by the authors during their participation in two public health intervention research (PHIR) projects, in France and in Burkina Faso.

RESULTS

In Paris, PHIR aimed to enable sub-Saharan immigrants to appropriate the existing means of prevention and sexual health care and to strengthen their empowerment in view of preserving their health. Evaluation was carried out using mixed methods. The intervention process theory is based on Ninacs' conceptual model of individual empowerment. The Consolidated Framework For Implementation Research (CFIR) was mobilized a posteriori to analyze the process. PHIR stemmed from collaboration between a research team and two associations. The different stakeholders were involved in the evaluation process, as were, at certain times, persons in highly precarious situations. In Ouagadougou, a community-based dengue vector control intervention was deployed to address an essential but neglected need. As regards evaluation, we opted for a holistic, mixed method approach (effectiveness and process). The contents of the intervention were determined based on tacit knowledge, a community preference survey and solid evidence. The theoretical framework of the intervention consisted in an eco-biological model of vector control. The implementation analysis combined an internal assessment of implementation fidelity with an external CFIR process analysis. All stakeholders were involved in the evaluation process.

DISCUSSION

Analysis confirmed not only the value of process evaluations in PHIR, but also the primordial importance of a rigorous approach. Stakeholder involvement is a major challenge to be addressed early in the planning of RISPs; with this in mind, effective and ethically sound assessment mechanisms need to be drawn up. Interdisciplinary evaluative approaches should be preferred, and the use of justified, relevant, and flexible frameworks is highly recommended.

CONCLUSION

Lessons learned for those wishing to engage in the process evaluation of a public health intervention are hereby presented.

[Dengue virus circulation in West Africa: An emerging public health issue]

Dengue is the most widespread arbovirosis in the world, with approximately 390 million cases per year, 96 millions of which have clinical manifestations and 25,000 deaths. In West Africa, the circulation of this virus in human populations was first reported in the 1960s in Nigeria. Clinical diagnosis of dengue in West Africa is made difficult by the existence of other diseases with similar clinical presentations. Biological diagnosis remains therefore the only alternative. This biological diagnosis requires high quality equipment and well-trained personnel, which are not always available in resource-limited countries. Thus, many cases of dengue fever are consistently reported as malaria, leading to mismanagement, which can have serious consequences on the health status of patients. It is therefore necessary to set up surveillance systems for febrile infections of unknown origin in Africa by strengthening the diagnostic capacities of national laboratories.

Review of the ecology and behaviour of Aedes aegypti and Aedes albopictus in Western Africa and implications for vector control

Western Africa is vulnerable to arboviral disease transmission, having recently experienced major outbreaks of chikungunya, dengue, yellow fever and Zika. However, there have been relatively few studies on the natural history of the two major human arbovirus vectors in this region, Aedes aegypti and Ae. albopictus, potentially limiting the implementation of effective vector control. We systematically searched for and reviewed relevant studies on the behaviour and ecology of Ae. aegypti and Ae. albopictus in Western Africa, published over the last 40 years. We identified 73 relevant studies, over half of which were conducted in Nigeria, Senegal, or Côte d'Ivoire. Most studies investigated the ecology of Ae. aegypti and Ae. albopictus, exploring the impact of seasonality and land cover on mosquito populations and identifying aquatic habitats. This review highlights the adaptation of Ae. albopictus to urban environments and its invasive potential, and the year-round maintenance of Ae. aegypti populations in water storage containers. However, important gaps were identified in the literature on the behaviour of both species, particularly Ae. albopictus. In Western Africa, Ae. aegypti and Ae. albopictus appear to be mainly anthropophilic and to bite predominantly during the day, but further research is needed to confirm this to inform planning of effective vector control strategies. We discuss the public health implications of these findings and comment on the suitability of existing and novel options for control in Western Africa.

Analyses of Insecticide Resistance Genes in Aedes aegypti and Aedes albopictus Mosquito Populations from Cameroon

The emergence of insecticide resistance in Aedes mosquitoes could pose major challenges for arboviral-borne disease control. In this paper, insecticide susceptibility level and resistance mechanisms were assessed in Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) from urban settings of Cameroon. The F1 progeny of Aedes aegypti and Aedes albopictus collected in Douala, Yaoundé and Dschang from August to December 2020 was tested using WHO tube assays with four insecticides: deltamethrin 0.05%, permethrin 0.75%, DDT 4% and bendiocarb 0.1%. TaqMan, qPCR and RT-qPCR assays were used to detect kdr mutations and the expression profiles of eight detoxification genes. Aedes aegypti mosquitoes from Douala were found to be resistant to DDT, permethrin and deltamethrin. Three kdr mutations, F1534C, V1016G and V1016I were detected in Aedes aegypti populations from Douala and Dschang. The kdr allele F1534C was predominant (90%) in Aedes aegypti and was detected for the first time in Aedes albopictus (2.08%). P450s genes, Cyp9J28 (2.23-7.03 folds), Cyp9M6 (1.49-2.59 folds), Cyp9J32 (1.29-3.75 folds) and GSTD4 (1.34-55.3 folds) were found overexpressed in the Douala and Yaoundé Aedes aegypti populations. The emergence of insecticide resistance in Aedes aegypti and Aedes albopictus calls for alternative strategies towards the control and prevention of arboviral vector-borne diseases in Cameroon.

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 community-based 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.

Analysis of the implementation of a community-based intervention to control dengue fever in Burkina Faso

BACKGROUND

A community-based dengue fever intervention was implemented in Burkina Faso in 2017. The results achieved vary from one area to another. The objective of this article is to analyze the implementation of this intervention, to better understand the process, and to explain the contextual elements of performance variations in implementation.

METHODOLOGY

The research was conducted in the former sector 22 of the city of Ouagadougou. We adapted the Consolidated Framework for Implementation Research (CFIR) to take into account the realities of the context and the intervention. The data collected from the participants directly involved in the implementation using three techniques: document consultation, individual interview, and focus group.

RESULTS

Two dimensions of CFIR emerge from the results as having had a positive influence on the implementation: (i) the characteristics of the intervention and (ii) the processes of the intervention implementation. The majority of the CFIR constructions were considered to have had a positive effect on implementation. The quality and strength of the evidence received the highest score. The dimension of the external context had a negative influence on the implementation of the intervention.

CONCLUSION

The objective of the study was to analyze the influence of contextual elements on the implementation process of a community-based dengue fever intervention. We used the CFIR framework already used by many studies for implementation analysis. Although it was not possible to test this framework in its entirety, it is useful for the analysis of the implementation. Its use is simple and does not require any special skills from users. Usability is indeed an essential criterion for the relevance of using an analytical framework in implementation science.