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BackgroundEntomological surveillance of lymphatic filariasis and malaria infections play an important role in the decision-making of national programs to control, or eliminate these both diseases. In areas where both diseases prevalence is low, a large number of mosquitoes need to be sampled to determine vectors infection rate. To do this, efficient mosquito collection methods must be used. This study is part in this framework, to assess appropriate mosquito collection methods for lymphatic filariasis xenomonitoring in a coexistence context with malaria in Burkina Faso.Methodology/principal findingsMosquito collections were performed between August and September 2018 in four villages (Koulpissi, Seiga, and Péribgan, Saptan), distributed in East and South-West health regions of Burkina Faso. Different collection methods were used: Human Landing Catches (HLC) executed indoor and outdoor, Window Exit-Trap, Double Net Trap (DNT) and Pyrethrum Spray Catches (PSC). Molecular analyses were performed to identify Anopheles gambiae s.l. sibling species and to detect Wuchereria bancrofti and Plasmodium falciparum infection in Anopheles mosquitoes. A total of 3 322 mosquitoes were collected among this, Anopheles gambiae s.l. was the vector caught in largest proportion (63.82%). An. gambiae s.l. sibling species molecular characterization showed that An. gambiae was the dominant specie in all villages. The Human Landing Catches (indoor and outdoor) collected the highest proportion of mosquitoes (between 61.5% and 82.79%). For the sampling vectors infected to W. bancrofti or P. falciparum, PSC, HLC and Window Exit-Trap were found the most effective collection methods.Conclusions/significanceThis study revealed that HLC indoor and outdoor remained the most effective collection method. Likewise, the results showed the probability to use Window Exit-Trap and PSC collection methods to sample Anopheles infected.

Abstract Background The use of urban lowlands for agriculture contributes to the food security of city- dwellers, but promotes malaria transmission. The objective of the study was to characterize the entomological drivers of malaria transmission in two lowlands (N’Gattakro and Odiennekourani) in the city of Bouaké, Côte d’Ivoire. Methods The human landing catch technique was used to capture mosquitoes in houses located at the edge of two lowlands in Bouaké from February to December 2019. Cultivated surfaces were calculated monthly in both lowlands for each crop type (rice and market gardening) using images acquired by a drone. The different mosquito species were identified morphologically and by PCR analysis for the Anopheles gambiae complex. Anopheles infection by Plasmodium parasites was assessed by quantitative PCR. Mosquito diversity, biting behaviour and rhythmicity, and malaria transmission were determined in each lowland and compared. Results Anopheles gambiae sensu lato (s.l.) was predominant in N’Gattakro and Culex quinquefasciatus in Odiennekourani. Four Anopheles species were identified: An. gambiae s.l. and Anopheles funestus s.l. in both lowlands, Anopheles pharoensis in N’Gattakro, and Anopheles ziemanni in Odiennekourani. Within the An. gambiae complex, three species were caught: An. gambiae sensu stricto (s.s.), Anopheles coluzzii, and Anopheles arabiensis for the first time in Côte d’Ivoire (30.1%, 69.9% and 0% in N’Gattakro, and 45.1%, 52.6% and 2.4% in Odiennekourani, respectively). Anopheles gambiae s.l. species exhibited a significant exophagic behaviour in N’Gattakro (77.1% of outdoor bites versus 52.2% in Odiennekourani). In N’Gattakro, 12.6% of captures occurred before bedtime (09.00 pm) and after waking up (05.00 am), 15.1% in Odiennekourani. The mean human biting rate was higher in N’Gattakro than in Odiennekourani (61.6 versus 15.5 bites per person per night). Overall, Anopheles infection rate was 0.68%, with 0.539 and 0.029 infected bites per person per night in N’Gattakro and Odiennekourani, respectively. Conclusion The risk of malaria in urban agricultural lowland areas is uneven. The role of agricultural developments and irrigation patterns in the production of larval habitat should be explored. The exophagic behaviour of Anopheles vectors raises the question of the residual transmission that needs to be assessed to implement appropriate control strategies.

Abstract Background Previous studies have revealed high malaria transmission in Bouaké, Côte d’Ivoire. The sociopolitical crisis in the country and the resulting environmental changes have raised the need to update existing knowledge on mosquito vector species and malaria transmission. Methods Adult mosquitoes were caught using the human landing catch (HLC) sampling method in Bouaké. They were collected in six districts representative of the diversity in urban landscapes. Sampling points were selected along the water network crossing the city and monitored from 2020 to 2021 to detect the presence of anopheline larvae. PCR techniques were used to ascertain the species of the Anopheles gambiae complex, Plasmodium falciparum sporozoite infection in a subset of Anopheles vectors, and insecticide resistance mechanisms in Anopheles arabiensis only. Results A total of 4599 Anopheles mosquitoes were collected and then identified. Anopheles gambiae sensu lato (s.l.) made up the majority of the whole collection (99%) while Anopheles funestus (0.7%), Anopheles ziemanni (0.2%), Anopheles pharoensis (0.2%) represented the remaining proportion of collection. Among the Anopheles gambiae complex, three species were identified namely An. gambiae sensu stricto (45.9%), Anopheles coluzzii (52.2%), and Anopheles arabiensis (1.9%). The first two species had already been collected in Bouaké, however this is the first time that An. arabiensis is reported in Côte d’Ivoire. Anopheles arabiensis was also collected during the larval surveys in a similar proportion (1.1%) in the same areas as the adults. Conclusions This study detected the presence of An. arabiensis for the first time in Côte d’Ivoire. This species was found quite far from its usual geographic area and its expansion could be linked to the urbanization process. Although no An. arabiensis was found to be infected by Plasmodium sp., its role in malaria transmission in Bouaké has to be explored, particularly since its exophagic behaviour raises the issue of control measures and the use of insecticide-impregnated nets. The spread of this species in Côte d'Ivoire should be assessed through further research in additional towns in the country.

Abstract Background The use of long-lasting insecticide-treated nets (LLINs) is one of the main malaria prevention method promoted by the World Health Organization (WHO) in Côte d'Ivoire. LLIN-coverage has reached 95% since 2015 and nearly 16 million LLINs were distributed in 2017. Despite these efforts, malaria incidence at the national level remains high (120‰ in 2012 to 164‰ in 2017) although this could be partly explained by increased screening efforts. This study aimed at determining what preventative measures were used against mosquito bites, as well as LLIN maintenance practices used by the inhabitants of the city of Bouaké, capital city of the Gbêkê region with a malaria incidence of 257‰ in 2017. Methods A descriptive qualitative investigation took place in Bouaké, in four neighbourhoods that were selected through purposive sampling based on their social composition. Data were collected using an interview guide based on convenience sampling. Results The results of the study reveal that LLINs are the most reported used malaria prevention measure (66.4%). Environmental health (28.8%) came second in their declarations, smoke coils (23.5%) third and aerosol cans (18.8%) last. The percentage of respondents who answered that they had slept under an LLIN the previous night was 53%. 57.7% reported that they wash their LLINs, 12.1% that they do not wash them, and 4% that they replace dirty LLINs with new ones. The LLINs washing methods described by the respondents did not comply with the WHO recommendations and there was no mention of LLINs repairs. Conclusion Despite mass distributions of LLINs in Côte d'Ivoire, this key malaria control tool remains under-used by the population. Regarding LLIN maintenance, more than half of the population reports that they wash their nets while not complying with recommended practices or repairing them.

The distribution of health care services in Bouaké, as it appears today, is the result of a long process rooted in both the history of the city and in health policies. This study thus focuses on the link between the logic of the establishment of health care structures and access to health care in Bouaké. The results, obtained from a census of all the health structures in the urban area and their geo-positioning, reveal that different rationales for their establishment are at work and that they are at the origin of socio-spatial inequalities in access to health care in Bouaké. Thus, the private sector is more concerned with profitability than with supporting the public sector. The faith-based private sector is characterized by its commitment to vulnerable households. As for the public sector, although it is guided by a desire to respect the health map, it offers poor technical facilities and limited capacity. These differentiated logics of installation result in a concentration of health care facilities in the city center and along the main roads. Health care facilities become scarce as one moves towards the periphery and areas that are difficult to access. This unequal distribution of the health care offer by health care sector reveals potential inequalities in the satisfaction of the health needs of the population.

Abstract Background This study reports an updated description on malaria vector diversity, behaviour, insecticide resistance and malaria transmission in the Diébougou and Dano peri-urban areas, Burkina Faso. Methods Mosquitoes were caught monthly using CDC light traps and pyrethrum spray catches. Mosquitoes were identified using morphological taxonomic keys. PCR techniques were used to identify the species of the Anopheles gambiae complex and insecticide resistance mechanisms in a subset of Anopheles vectors. The Plasmodium sporozoite infection status and origins of blood meals of female mosquitoes were determined by ELISA methods. Larvae were collected, breed in the insectary and tested for phenotypic resistance against four insecticides using WHO bioassays. Results This study contributed to update the entomological data in two peri-urban areas of Southwest Burkina Faso. Anopheles populations were mostly anthropophilic and endophilic in both areas and exhibit high susceptibility to an organophosphate insecticide. This offers an alternative for the control of these pyrethroid-resistant populations. These data might help the National Malaria Control Programme for decision-making about vector control planning and resistance management. Conclusions This study contributed to update the entomological data in two peri-urban areas of Southwest Burkina Faso. Anopheles populations were mostly anthropophilic and endophilic in both areas and exhibit high susceptibility to an organophosphate insecticide. This offers an alternative for the control of these pyrethroid-resistant populations. These data might help the National Malaria Control Programme for decision-making about vector control planning and resistance management.

Vector-borne diseases are a constantly renewed threat to human health. Vectors adaptation, climate change, environment modifications, globalization, urbanization, promote the persistence or even the emergence and diffusion of these infectious risks. In Brazil, today’s preoccupations are focused on Aedes transmitted arboviruses. The country is facing the rise of dengue, Zika, Chikungunya and the persistence of yellow fever. Other vector-borne diseases such as schistosomiasis, persist around the irrigated perimeters of Sao Francisco River. The spatial dynamics of these diseases underline the role of the structuring of spaces, the functioning of networks, the growth of urbanization, and the supply of care, echoing studies carried out around vector-borne diseases, in other places and on other continents. By recalling the geographical teachings resulting from some interdisciplinary work examples, we propose to renew the focus on vector-borne diseases by confronting experiences on both sides of the Atlantic, or even then South American borders.

Abstract 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.

Abstract Background The sterile insect technique (SIT) is a vector control strategy relying on the mass release of sterile males into wild vector populations. Current sex separation techniques are not fully efficient and could lead to the release of a small proportion of females. It is therefore important to evaluate the effect of irradiation on the ability of released females to transmit pathogens. This study aimed to assess the effect of irradiation on the survival and competence of Anopheles arabiensis females for Plasmodium falciparum in laboratory conditions. Methods Pupae were irradiated at 95 Gy of gamma-rays, and emerging females were challenged with one of 14 natural isolates of P. falciparum. Seven days post-blood meal (dpbm), irradiated and unirradiated-control females were dissected to assess the presence of oocysts, using 8 parasite isolates. On 14 dpbm, sporozoite dissemination in the head/thorax was also examined, using 10 parasites isolates including 4 in common with the 7 dpbm dissection (oocyst data). The survivorship of irradiated and unirradiated-control mosquitoes was monitored. Results Overall, irradiation reduced the proportion of mosquitoes infected with the oocyst stages by 17% but this effect was highly inconsistent among parasite isolates. Secondly, there was no significant effect of irradiation on the number of developing oocysts. Thirdly, there was no significant difference in both the sporozoite infection rate and load between the irradiated and unirradiated-control mosquitoes. Fourthly, irradiation had varying effects on female survival with either a negative effect or no effect. Conclusions The effect of irradiation on mosquito competence strongly varied among parasite isolates. Because of such isolate variability and, the fact that different parasite isolates were used to collect oocyst and sporozoite data, the irradiation-mediated reduction of oocyst prevalence was not confirmed for the sporozoite stages. Our data indicate that irradiated female An. arabiensis could contribute to malaria transmission, and highlight the need for perfect sexing tools, which would prevent the release of females as part of SIT programmes.

Abstract Background Dengue is increasing in its global presence with an estimated 4 billion people at-risk of infection in at least 128 countries. Despite the promising results of EcoHealth and community mobilization approaches to Aedes reduction, more evidence of their efficacy on reducing dengue risk is needed. The principal research question is to determine if interventions based upon community mobilization reduce the risk of dengue virus infection among children 3 to 9 years old compared to usual dengue control practice in Fortaleza, Brazil. Methods The present study will follow a pragmatic cluster randomized controlled trial (cRCT) design with randomization at the census tract level with equal allocation to the two arms. In each arm, there will be 34 clusters of 86 children between 3 to 9 years old for an expected total of 5848 children enrolled in the study, assuming a risk reduction of 29.5% based upon findings from a previous multi-site cRCT. The primary outcomes are rates of anti-dengue Immunoglobulin G (IgG) seroconversion and adult female Aedes density. The intervention is based upon a participatory health research approach, Socializing Evidence for Participatory Action (SEPA), where the research evidence is used to foster community engagement and ownership of the health issue and solution. Following allocation, intervention communities will develop and implement their own solutions that will likely include a wide variety of collective events and media approaches. Data collection activities over a period of 3 years include household visits for blood collection, household surveys, and entomological surveys; and qualitative activities including focus groups, in-depth interviews, and document analysis to evaluate the process, acceptability, fidelity, and sustainability of the intervention. Study participants will be aware of their assignment and all research staff will be blinded although the intervention assignment will likely be revealed to field staff through interaction with participants. Discussion The results of our study will provide evidence on community mobilization as an intervention for dengue control. We anticipate that if community mobilization is effective in Fortaleza, the results of this study will help develop evidence-based vector control programs in Brazil, and also in other countries struggling with Aedes-transmitted diseases. Trial registration ISRCTN66131315, registration date: 1 October 2018.

Abstract Background Although larviciding may be a valuable tool to supplement long-lasting insecticide nets (LLINs) in West Africa in different ecological settings, its actual impact on malaria burden and transmission has yet to be demonstrated. A randomized controlled trial was therefore undertaken to assess the effectiveness of larviciding using Bacillus thuringiensis israeliensis (Bti) in addition to the use of LLINs. In order to optimally implement such a larviciding intervention, we first aimed to identify and to characterize the breeding habitats of Anopheles spp. in the entire study area located in the vicinity of Korhogo in northern Côte d’Ivoire. Methods We conducted two surveys during the rainy and the dry season, respectively, in the thirty villages around Korhogo involved in the study. In each survey, water bodies located within a 2 km radius around each village were identified and assessed for the presence of mosquito larvae. We morphologically identified the larvae to the genus level and we characterized all of the habitats positive for Anopheles spp. larvae based on a predefined set of criteria. Results Overall, 620 and 188 water bodies positive for Anopheles spp. larvae were sampled in the rainy and the dry season, respectively. A broad range of habitat types were identified. Rice paddies accounted for 61% and 57% of the habitats encountered in the rainy and the dry season, respectively. In the rainy season, edges of rivers and streams (12%) were the second most abundant habitats for Anopheles spp. larvae. More than 90% of the Anopheles spp. breeding habitats were surrounded by green areas. Dams, ponds and drains produced higher numbers of Anopheles spp. larvae per square meter than rice paddies (RR = 1.51; 95% CI: 1.18–1.94; P = 0.0010). The density of Anopheles spp. larvae was significantly higher in habitats surrounded by low-density housing (RR = 4.81; 95% CI: 1.84–12.60; P = 0.0014) and green areas (RR = 3.96; 95% CI: 1.92–8.16; P = 0.0002] than habitats surrounded by high-density housing. Turbid water [RR = 1.42 (95% CI: 1.15–1.76; P = 0.0012) was associated with higher densities of Anopheles spp. larvae. The likelihood of finding mosquito pupae in Anopheles spp. breeding habitats was higher in the dry season (OR = 5.92; 95% CI: 2.11–16.63; P = 0.0007) than in the rainy season. Conclusions Rice paddies represented the most frequent habitat type for Anopheles spp. larvae in the Korhogo area during both the rainy and the dry seasons. Anopheles spp. breeding habitats covered a very large and dynamic area in the rainy season whereas they were fewer in number in the dry season. In this context, implementing a larviciding strategy from the end of the rainy season to the dry season is presumably the most cost-effective strategy.

BackgroundTwenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial.MethodsWe carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations.ResultsEight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively.ConclusionThe entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.

We evaluated the effectiveness of a community-based intervention for dengue vector control in Ouagadougou, the capital city of Burkina Faso. Households in the intervention (n = 287) and control (n = 289) neighborhoods were randomly sampled and the outcomes collected before the intervention (October 2015) and after the intervention (October 2016). The intervention reduced residents’ exposure to dengue vector bites (vector saliva biomarker difference −0.08 [95% CI −0.11 to −0.04]). The pupae index declined in the intervention neighborhood (from 162.14 to 99.03) and increased in the control neighborhood (from 218.72 to 255.67). Residents in the intervention neighborhood were less likely to associate dengue with malaria (risk ratio 0.70 [95% CI 0.58–0.84]) and had increased knowledge about dengue symptoms (risk ratio 1.44 [95% CI 1.22–1.69]). Our study showed that well-planned, evidence/community-based interventions that control exposure to dengue vectors are feasible and effective in urban settings in Africa that have limited resources.

Abstract 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.

Abstract Background Urbanization is a main trend in developing countries and leads to health transition. Although non-communicable diseases are increasing in cities of low-income countries, vector-borne diseases such as malaria, are still present. In the case of malaria, transmission is lower than in rural areas, but is uneven and not well documented. In this study, we wanted to evaluate intra-urban malaria transmission in a West African country (Burkina Faso). Methods A cross-sectional study on 847 adults (35 to 59 year-old) and 881 children (6 months to 5 year-old) living in 1045 households of four districts (Dogona, Yeguere, Tounouma and Secteur 25) of Bobo-Dioulasso was performed between October and November 2013. The districts were selected according to a geographical approach that took into account the city heterogeneity. Malaria prevalence was evaluated using thick and thin blood smears. Human exposure to Anopheles bites was measured by assessing the level of IgG against the Anopheles gSG6-P1 salivary peptide. Adult mosquitoes were collected using CDC traps and indoor insecticide spraying in some houses of the four neighbourhoods. The Anopheles species and Plasmodium falciparum infection rate were determined using PCR assays. Results In this study, 98.5% of the malaria infections were due to Plasmodium falciparum. Malaria transmission occurred in the four districts. Malaria prevalence was higher in children than in adults (19.2 vs 4.4%), and higher in the central districts than in the peripheral ones (P = 0.001). The median IgG level was more elevated in P. falciparum-infected than in non-infected individuals (P < 0.001). Anopheles arabiensis was the main vector identified (83.2%; 227 of the 273 tested mosquito specimens). Five P. falciparum-infected mosquitoes were caught, and they were all caught in the central district of Tounouma where 28.6% (14/49) of the tested blood-fed mosquito specimens had a human blood meal. Conclusions This study showed that urban malaria transmission occurred in Bobo-Dioulasso, in all the four studied areas, but mainly in central districts. Environmental determinants primarily explain this situation, which calls for better urban management.

Abstract Background A novel strategy applying an organophosphate-based insecticide paint on doors and windows in combination with long-lasting insecticide-treated nets (LLINs) was tested for the control of pyrethroid-resistant malaria vectors in a village setting in Vallée du Kou, a rice-growing area west of Burkina Faso. Methods Insecticide Paint Inesfly 5A IGR™, comprised of two organophosphates and an insect growth regulator, was applied to doors and windows and tested in combination with pyrethroid-treated LLINs. The killing effect was monitored for 5 months by early morning collections of anophelines and other culicids. The residual efficacy was evaluated monthly by WHO bioassays using Anopheles gambiae ‘Kisumu’ and local populations of Anopheles coluzzii resistant to pyrethroids. The spatial mortality efficacy (SME) at distances of 1 m was also assessed against pyrethroid-susceptible and -resistant malaria vectors. The frequency of L1014F kdr and Ace-1 R G119S mutations was, respectively, reported throughout the study. The Insecticide Paint Inesfly 5A IGR had been tested in past studies yielding a long-term mortality rate of 80% over 12 months against An. coluzzii, the local pyrethroid-resistant malaria vector. The purpose of the present study is to test if treating smaller, targeted surfaces (e.g. doors and windows) was also efficient in killing malaria vectors. Results Treating windows and doors alone yielded a killing efficacy of 100% for 1 month against An. coluzzii resistant to pyrethroids, but efficacy reduced quickly afterwards. Likewise, WHO cone bioassays yielded mortalities of 80–100% for 2 months but declined to 90 and 40% 2 and 3 months after treatment, respectively. Mosquitoes exposed to insecticide paint-treated surfaces at distances of 1 m, yielded mortality rates of about 90–80% against local pyrethroids-resistant An. coluzzii during the first 2 months, but decreased to 30% afterwards. Anopheles coluzzii was reported to be exclusively the local malaria vector and resistant to pyrethroids with high L1014 kdr frequency. Conclusion The combination of insecticide paint on doors and windows with LLINs yielded high mortality rates in the short term against wild pyrethroid-resistant malaria vector populations. A high SME was observed against laboratory strains of pyrethroid-resistant malaria vectors placed for 30 min at 1 m from the treated/control walls. The application of the insecticide paint on doors and windows led to high but short-lasting mortality rates. The strategy may be an option in a context where low cost, rapid responses need to be implemented in areas where malaria vectors are resistant to pyrethroids.

Abstract Background The success of the sterile insect technique depends, among other things, on continuous releases of sexually competitive sterile males within the target area. Several factors (including high rearing density and physical manipulation, such as larvae and pupae separation) can influence the quality of males produced in mass-rearing facilities. The different steps in mass production in the laboratory may modify the behaviour of mosquitoes, directly or through loss of natural characters as a result of adaptation to lab rearing, and lead to the competitiveness of sterile male being reduced. In the present study, the objective was to evaluate the effect of mass-rearing conditions on sterile male sexual competitiveness in semi-field cages compared to routine small scale laboratory rearing methods. Methods Anopheles arabiensis immature stages were reared both on a large scale using a rack and tray system developed by the FAO/IAEA (MRS), and on a small scale using standard laboratory rearing trays (SRS). Mosquito life history traits such as pupation rate, emergence rate, adult size as well as the effect of irradiation on adult longevity were evaluated. Moreover, 5–6 day old mosquitoes were released into field cages and left for two nights to mate and the mating competitiveness between sterile mass-reared males and fertile males reared on a small scale when competing for small scale reared virgin females was investigated. Resulting fertility in a treatment ratio of 1:1:1 (100 irradiated males: 100 non-irradiated males: 100 virgin females) was compared to control cages with 0:100:100 (non-irradiated control) and 100:0:100 (irradiated control). Results No significant differences in life history parameters were observed between rearing methods. The competitiveness index of mass reared males (0.58) was similar to males reared on a small scale (0.59). A residual fertility rate of 20% was observed in the irradiated control (100:0:100), measured as the percentage of eggs collected from the cages which developed to adulthood. No significant difference was observed (t = 0.2896, df = 4, P = 0.7865) between the rearing treatments (MRS and SRS) in the fertility rate, a measure of mating competitiveness. Conclusions The results showed that the FAO/IAEA mass-rearing process did not affect mosquito life history parameters or the mating competitiveness of males.

Abstract Background Many cities in developing countries experience an unplanned and rapid growth. Several studies have shown that the irregular urbanization and equipment of cities produce different health risks and uneven exposure to specific diseases. Consequently, health surveys within cities should be carried out at the micro-local scale and sampling methods should try to capture this urban diversity. Methods This article describes the methodology used to develop a multi-stage sampling protocol to select a population for a demographic survey that investigates health disparities in the medium-sized city of Bobo-Dioulasso, Burkina Faso. It is based on the characterization of Bobo-Dioulasso city typology by taking into account the city heterogeneity, as determined by analysis of the built environment and of the distribution of urban infrastructures, such as healthcare structures or even water fountains, by photo-interpretation of aerial photographs and satellite images. Principal component analysis and hierarchical ascendant classification were then used to generate the city typology. Results Five groups of spaces with specific profiles were identified according to a set of variables which could be considered as proxy indicators of health status. Within these five groups, four sub-spaces were randomly selected for the study. We were then able to survey 1045 households in all the selected sub-spaces. The pertinence of this approach is discussed regarding to classical sampling as random walk method for example. Conclusion This urban space typology allowed to select a population living in areas representative of the uneven urbanization process, and to characterize its health status in regards to several indicators (nutritional status, communicable and non-communicable diseases, and anaemia). Although this method should be validated and compared with more established methods, it appears as an alternative in developing countries where geographic and population data are scarce.

Malaria is a parasitic vector disease whose transmission is linked to a combination of multiple factors related to the vector, the parasite, the human host and its environment. In addition to the high prevalence in the tropical zone, the endemic malaria area, there are significant disparities in the transmission of the disease between rural and urban areas, where the highest prevalence of malaria is observed, but also within the cities themselves. While the city, which appears to be unfavourable to the vector and should therefore contribute to reducing malaria transmission, can be observed to maintain it. However, the transmission is uneven because of certain intrinsic characteristics of the city described as heterogeneous, dense and open. In Bouaké, the second largest city in the Ivory Coast after Abidjan, several years of military-political crisis have resulted in emptying some neighborhoods where the bush has regained ground, increasing the density where populations have remained, disrupting the health care system and weakening the economic power of the city dwellers. Using a geographical approach, our study aimed to measure the risk of malaria transmission in urban sub-spaces illustrating the changes undergone by the city during the crisis and to identify the factors that make it possible to explain the spatial disparities in the distribution of malaria. A geographical survey identified Kennedy and Dar-Es-Salam 1 as urban sub-spaces. An update of land use was conducted using field surveys and Google Earth to establish a geographical database for use in the analysis of sociological, parasitological and entomological data which were collected during several field surveys. The land use update showed that only 50.5% of the developed lots were inhabited in Kennedy, compared with 91.5% in Dar-Es-Salam 1. Parasitological data showed that the prevalence of malaria was significantly higher at Kennedy (33.5%) compared to Dar-Es-Salam 1 (10.2%) (p = 0.0001). Similarly, the aggressiveness of vector mosquitoes (Anopheles gambiae s.l.) was higher in Kennedy (20.6 p / h / n) than in Dar-Es-Salam 1 (1.2 p / h / n) (p = 0.0001). Sociological surveys revealed a different use of prevention tools by neighborhood, but rates of possession of long-lasting treated mosquito nets and ways of seeking care were similar. Results showed significant spatial disparities in the transmission of malaria in the two neighborhoods studied, while the practices of prevention and health care do not really differ.

Background: A severe outbreak of dengue occurred in Burkina Faso in 2016, with the most cases reported in Ouagadougou, that highlights the necessity to implement vector surveillance system. This study aims to estimate the risk of arboviruses transmission and the insecticide susceptibility status of potential vectors in four sites in Burkina Faso.Methods: From June to September 2016, house-to-house cross sectional entomological surveys were performed in four cities stretching along a southwest-to-northeast railway transect. The household surveys analyzed the presence of Aedes spp. larvae in containers holding water and the World Health Organization (WHO) larval abundance indices were estimated. WHO tube assays was used to evaluate the insecticide susceptibility within Aedes populations from these localities.Results: A total of 31,378 mosquitoes' larvae were collected from 1,330 containers holding water. Aedes spp. was the most abundant (95.19%) followed by Culex spp. (4.75%). Aedes aegypti a key vector of arboviruses (ARBOV) in West Africa was the major Aedes species found (98.60%). The relative larval indices, house index, container and Breteau indexes were high, up to 70, 35, and 10, respectively. Aedes aegypti tended to breed mainly in discarded tires and terracotta jars. Except in Banfora the western city, Ae. aegypti populations were resistant to deltamethrin 0.05% in the other localities with low mortality rate under 20% in Ouagadougou whereas they were fully susceptible to malathion 5% whatever the site. Intermediate resistance was observed in the four sites with mortality rates varying between 78 and 94% with bendiocarb 0.1%.Conclusions: This study provided basic information on entomological indices that can help to monitor the risks of ARBOV epidemics in the main cities along the railway in Burkina Faso. In these cities, all larval indices exceeded the risk level of ARBOV outbreak. Aedes aegypti the main species collected was resistant to deltamethrin 0.05% and bendiocarb 0.1% whereas they were fully susceptible to malathion 5%. The monitoring of insecticide resistance is also important to be integrated to the vector surveillance system in Burkina Faso.

In West Africa, Aedes aegypti remains the major vector of dengue virus. Since 2013, dengue fever has been reemerging in Burkina Faso with annual outbreaks, thus becoming a major public health problem. Its control relies on vector control, which is unfortunately facing the problem of insecticide resistance. At the time of this study, although data on phenotypic resistance were available, information related to the metabolic resistance in Aedes populations from Burkina Faso remained very scarce. Here, we assessed the phenotypic and the metabolic resistance of Ae. aegypti populations sampled from the two main urban areas (Ouagadougou and Bobo-Dioulasso) of Burkina Faso. Insecticide susceptibility bioassays to chlorpyriphos-methyl 0.4%, bendiocarb 0.1% and deltamethrin 0.05% were performed on natural populations of Ae. aegypti using the WHO protocol. The activity of enzymes involved in the rapid detoxification of insecticides, especially non-specific esterases, oxidases (cytochrome P450) and glutathione-S-transferases, was measured on individual mosquitos. The mortality rates for deltamethrin 0.05% were low and ranged from 20.72% to 89.62% in the Bobo-Dioulasso and Ouagadougou sites, respectively. When bendiocarb 0.1% was tested, the mortality rates ranged from 7.73% to 71.23%. Interestingly, in the two urban areas, mosquitoes were found to be fully susceptible to chlorpyriphos-methyl 0.4%. Elevated activity of non-specific esterases and glutathione-S-transferases was reported, suggesting multiple resistance mechanisms involved in Ae. aegypti populations from Bobo-Dioulasso and Ouagadougou (including cytochrome P450). This update to the insecticide resistance status within Ae. aegypti populations in the two biggest cities is important to better plan dengue vectors control in the country and provides valuable information for improving vector control strategies in Burkina Faso, West Africa.

Swarming is a key part of the natural system of reproduction of anopheline mosquito populations, and a better understanding of swarming and mating systems in a targeted species in its natural habitat would contribute to better design control strategies with a greater chance of success. Our study investigated the monthly occurrence of swarming and the mating frequency (within swarms) of Anopheles arabiensis in Dioulassoba, Burkina Faso and their relationship with local environmental factors. Mosquitoes collected from swarms were described in terms of body size, recent sugar meal intake, and female repletion, insemination, and Plasmodium falciparum infection status. Swarms of An. arabiensis were found in each month of the year. Both start and end times of swarming varied significantly between months, correlating with the time of sunset. Swarming mostly started after or coincided with sunset from late July to early October but occurred before sunset from late October to early July. Swarming duration, the number of mosquitoes and mating pairs per swarm, and time to first mating were significantly different between months in an inverse relationship with the monthly rainfall. The number of mating pairs was strongly and positively correlated with swarm size. Almost all the females caught in copula were inseminated but a very few were blood fed; no P. falciparum infection was observed. Males caught in copula and in solo were similar in body size and in the proportion which had taken a recent sugar meal. Our investigations showed that An. arabiensis reproductive activities are most frequent during the dry season, suggesting either the species' preference for dry climatic conditions or a lack of available breeding sites during the rainy season due to the seasonal flooding in this area. Targeting interventions to kill mosquitoes in swarms or to achieve an over-flooding ratio of sterile males during the rainy season would increase their efficiency in reducing the population density of this vector.

To put spatial health disparities in Ouagadougou in relation to the processes of urbanization, we realize from a satellite image a stratification according to criteria’s, which resume the urbanization: building density and area regularity. From this stratification it is possible to carry out a health survey near the populations which reside in different urban spaces. Textural analysis is a technique to determine the space high frequencies. We used it to characterize the building on the satellite image panchromatic SPOT 5. It proves very satisfactory to localize the building when only a panchromatic image is available.

OBJECTIVE: To determine why patients attend dental-care facilities in Ouagadougou, Burkina Faso and to improve understanding of the capacity of oral health-care services in urban west Africa. METHODS: We studied a randomly selected sample of patients attending 15 dental-care facilities in Ouagadougou over a 1-year period in 2004. Data were collected using a simple daily record form. FINDINGS: From a total of 44 975 patients, the final sample was established at 14 591 patients, of whom 55.4% were new patients and 44.6% were "booking patients". Most patients seeking care (71.9%) were aged 15-44 years. Nongovernmental not-for-profit dental services were used by 41.5% of all patients, 36% attended private dental-care services, and 22.5% of patients visited public services. The most common complaint causing the patient to seek dental-care services was caries with pulpal involvement (52.4%), and 60% of all complaints were associated with pain. The patients' dental-care requirements were found to differ significantly according to sex, health insurance coverage and occupation. CONCLUSION: Urban district health authorities should ensure provision of primary health-care services, at the patients' first point of contact, which are directed towards the relief of pain. In addition to the strengthening of outreach emergency care, health centres should also contribute to the implementation of community-based programmes for the prevention of oral disease and the promotion of oral health. Exchange of experiences from alternative oral health-care systems relevant to developing countries is urgently needed for tackling the growing burden of oral disease.

The aetiological diagnostic of fevers in Laos remains difficult due to limited laboratory diagnostic facilities. However, it has recently become apparent that both scrub and murine typhus are common causes of previous undiagnosed fever. Epidemiological data suggests that scrub typhus would be more common in rural areas and murine typhus in urban areas, but there is very little recent information on factors involved in scrub and murine typhus transmission, especially where they are sympatric - as is the case in Vientiane, the capital of the Lao PDR.We therefore determined the frequency of IgG seropositivity against scrub typhus (Orientia tsutsugamushi) and murine typhus (Rickettsia typhi), as indices of prior exposure to these pathogens, in randomly selected adults in urban and peri-urban Vientiane City (n = 2,002, ≥35 years). Anti-scrub and murine typhus IgG were detected by ELISA assays using filter paper elutes. We validated the accuracy of ELISA of these elutes against ELISA using serum samples. The overall prevalence of scrub and murine typhus IgG antibodies was 20.3% and 20.6%, respectively. Scrub typhus seropositivity was significantly higher among adults living in the periphery (28.4%) than in the central zone (13.1%) of Vientiane. In contrast, seroprevalence of murine typhus IgG antibodies was significantly higher in the central zone (30.8%) as compared to the periphery (14.4%). In multivariate analysis, adults with a longer residence in Vientiane were at significant greater risk of past infection with murine typhus and at lower risk for scrub typhus. Those with no education, living on low incomes, living on plots of land with poor sanitary conditions, living in large households, and farmers were at higher risk of scrub typhus and those living in neighborhoods with high building density and close to markets were at greater risk for murine typhus and at lower risk of scrub typhus past infection.This study underscores the intense circulation of both scrub and murine typhus in Vientiane city and underlines difference in spatial distribution and risk factors involved in the transmission of these diseases.

Vector-borne diseases are a constantly renewed threat to human health. Vectors adaptation, climate change, environment modifications, globalization, urbanization, promote the persistence or even the emergence and diffusion of these infectious risks. In Brazil, today’s preoccupations are focused on Aedes transmitted arboviruses. The country is facing the rise of dengue, Zika, Chikungunya and the persistence of yellow fever. Other vector-borne diseases such as schistosomiasis, persist around the irrigated perimeters of Sao Francisco River. The spatial dynamics of these diseases underline the role of the structuring of spaces, the functioning of networks, the growth of urbanization, and the supply of care, echoing studies carried out around vector-borne diseases, in other places and on other continents. By recalling the geographical teachings resulting from some interdisciplinary work examples, we propose to renew the focus on vector-borne diseases by confronting experiences on both sides of the Atlantic, or even then South American borders.