Background Twenty-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. Methods We 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. Results Eight 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. Conclusion The 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.

A better understanding of malaria transmission at a local scale is essential for developing and implementing effective control strategies. In the framework of a randomized controlled trial (RCT), we aimed to provide an updated description of malaria transmission in the Korhogo area, northern Côte d’Ivoire, and to obtain baseline data for the trial. We performed human landing collections (HLCs) in 26 villages in the Korhogo area during the rainy season (September–October 2016, April–May 2017) and the dry season (November–December 2016, February–March 2017). We used PCR techniques to ascertain the species of the Anopheles gambiae complex, Plasmodium falciparum sporozoite infection, and insecticide resistance mechanisms in a subset of Anopheles vectors. Anopheles gambiae s.l. was the predominant malaria vector in the Korhogo area. Overall, more vectors were collected outdoors than indoors (p < 0.001). Of the 774 An. gambiae s.l. tested in the laboratory, 89.65% were An. gambiae s.s. and 10.35% were An. coluzzii. The frequencies of the kdr allele were very high in An. gambiae s.s. but the ace-1 allele was found at moderate frequencies. An unprotected individual living in the Korhogo area received an average of 9.04, 0.63, 0.06 and 0.12 infected bites per night in September–October, November–December, February–March, and April–May, respectively. These results demonstrate that the intensity of malaria transmission is extremely high in the Korhogo area, especially during the rainy season. Malaria control in highly endemic areas such as Korhogo needs to be strengthened with complementary tools in order to reduce the burden of the disease.

Urban malaria is an underestimated serious health concern in African countries. This study aimed to evaluate the risk of malaria transmission in an urban area by evaluating the level of human exposure to bites using an salivary biomarker ( Salivary Gland Protein-6 peptide 1 [gSG6-P1] peptide). Two multidisciplinary cross-sectional studies were undertaken in five sites of Bouaké city (three urban districts and two surrounding villages, used as control; Côte d'Ivoire) during the rainy season and the dry season. Blood samples were obtained from children 6 months to 14 years of age for immunological tests. The level of anti-gSG6-P1 immunoglobulin G (IgG) antibodies was significantly higher in the rainy season than the dry season in both urban and rural sites ( < 0.0001). Interestingly, children with the highest anti-gSG6-P1 IgG responses in the rainy season were infected by . Surprisingly, no difference of anti-gSG6-P1 IgG level was observed between urban and rural areas, for either season. The current data suggest that children in the urban city of Bouaké could be as highly exposed to bites as children living in surrounding villages. The immunological biomarker of human exposure to bites may be used to accurately assess the potential risk of malaria transmission in African urban settings.

Background Biotic and abiotic factors have been reported to affect the larvicidal efficacy of Bacillus thuringiensis israelensis ( Bti ) and Bacillus sphaericus ( Bs ), although the extent to which they are affected has been poorly documented. This paper studies the effect of sunlight exposure on the efficacy of a new larvicide formulation based on both Bti and Bs , herein after referred to as BTBSWAX, applied against two different larval stages. Methods The emergence of inhibition exhibited by BTBSWAX at three different dosages (1 g/m 2 , 1.5 g/m 2 , and 2 g/m 2 ) was monitored under semi-field conditions using a total of 32 containers comprising 16 that were covered and 16 that were uncovered. Two experiments were conducted using first- and second-instar larvae of Anopheles gambiae , respectively. Results BTBSWAX at 2 g/m 2 in covered containers exhibited high emergence inhibition (> 80%) when larvae were exposed from 1st instar on day-6 post-treatment, whereas the emergence inhibition was only 28% in uncovered containers. For larvae exposed from 1st instar on day-12 post-treatment, the emergence inhibition was moderate (70%) in covered containers but was low (< 20%) in uncovered containers. For larvae exposed from 2nd instar on day-10 post-treatment, the emergence inhibition was moderate (31%) in covered containers but was very low (< 10%) in uncovered containers. Moreover, the residual efficacy of BTBSWAX was markedly affected by environmental stresses, including sunlight exposure (Hazard ratio (HR) = 0.12, p < 0.001 and HR = 0.63, p = 0.033 for BTBSWAX at 2 g/m 2 against 1st and 2nd instar larvae, respectively). Conclusion These findings emphasize the impact of environmental variables (e.g., sunlight exposure) on the residual efficacy of Bti and Bs biolarvicides in the field. They hence highlight the need to take these factors into account for larvicide formulation development processes. Moreover, studies of the ecology of Anopheles larvae in targeted areas are also crucial for the integration of larval control strategies into malaria transmission plans devised by national malaria control programmes of endemic countries. Electronic supplementary material The online version of this article (10.1186/s12936-019-2687-0) contains supplementary material, which is available to authorized users.

Background: In malaria-endemic areas, human populations are frequently exposed to immunomodulatory salivary components injected during mosquito blood feeding. The consequences on pathogen-specific immune responses are not well known. This study evaluated and compared the humoral responses specific to merozoite stage vaccine candidates of Plasmodium falciparum, in children differentially exposed to Anopheles bites in a natural setting. Methods:The cross-sectional study was carried out in Bouaké (Côte d'Ivoire) where entomological data and blood samples from children (0-14 years) were collected in two sites with similar malaria prevalence. Antibody (IgG, IgG1, IgG3) responses to PfAMA1 and PfMSP1 were evaluated by ELISA. Univariate and multivariate analysis were performed to assess the relationship between the immune responses to P. falciparum antigens and exposure to Anopheles bites in the total cohort and in each site, separately. The individual level of exposure to Anopheles bites was evaluated by quantifying specific IgG response to the Anopheles gSG6-P1 salivary peptide, which represents a proxy of Anopheles exposure.

22Background: The present study presents results of entomological surveys conducted to 23 address the malaria vectors bionomic, insecticide resistance and transmission prior to the 24 implementation of new strategies complement long-lasting insecticidal nets (LLINs) in the 25 framework of a randomized control trial in southwest Burkina Faso. 26 Methods: We conducted entomological surveys in 27 villages during the dry cold season 27 (January 2017), dry hot season (March 2017) and rainy season (June 2017). We carried out 28 hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the 29 Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic 30 keys. Specimens belonging to the Anopheles gambiae complex and Funestus Group were 31 identified using molecular techniques as well as detection of Plasmodium falciparum 32 infection and insecticide resistance target-site mutations. 33 Results: Eight Anopheles species were detected in the area. Anopheles funestus s.s was the 34 main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry 35 hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the 36 rainy season. Species composition of the Anopheles population varied significantly among 37 surveys. All researched target site mutation of insecticide resistance (kdr-w, kdr-e and ace-1) 38 were detected in all members of the An. gambiae complex of the area but at different 39 frequencies. We observed early and late biting phenotypes in the main malaria vector species. 40 Entomological inoculation rates were 0.087, 0.089 and 0.375 infected bites per human per 41 night during dry cold season, dry hot season and rainy season, respectively. 42 Conclusion: The intensity of malaria transmission was high despite the universal coverage 43 with LLINs. We detected early and late biting phenotypes in the main malaria vector species 44 as well as physiological insecticide resistance mechanisms. These vectors might mediate 45 residual transmission. These data highlight the need to develop complementary tools in 46 3 addition to LLINs in order to better control resistant malaria vectors and to monitor 47 insecticide resistance. 48

Background: The objective of this study was to update malaria epidemiological profile prior to the implementation of a randomized controlled trial aiming to evaluate the efficacy of new vector control tools in complementary to the use of long-lasting insecticidal nets in Burkina Faso. Methods: We carried out active and passive cross-sectional surveys to estimate the prevalence and incidence of malaria infection from August 2016 to July 2017 in 27 villages of the Diebougou health district. Results: With the passive survey, we extracted data from 4814 patients included in the study from August 2016 to July 2017. Malaria incidence showed a seasonal distribution, with an overall incidence rate estimated at 414.3 per 1000 person-years. In the active cross sectional surveys, we enrolled 2839, 2594 and 2337 participants respectively in September 2016, December 2016 and June 2017. Prevalence of malaria infection were respectively 41.5%, 43.5% and 32.3% in September 2016, in December 2016 and June 2017. Multivariate analysis showed that girls seemed to have a lower risk of malaria infection (OR = 0.86; 95% CI = 0.79 - 0.95; p = 0.004). The risk of malaria infection was significantly lower in third survey (June 2017) at the beginning of the rainy season (OR = 0.69; 95% CI = 0.6 - 0.8; p < 0.001) compared to the first survey (September 2016) which was performed during the rainy season. Children aged 6 to 59 months had a higher risk of malaria infection compared to those aged 10 to 17 years (OR = 0.58; 95% CI = 0.51 - 0.66). Conclusion: Malaria burden remains high in this region of Burkina Faso despite substantial efforts made in malaria control during this current decade. Children under 5 years old were subject of malaria burden in this setting. This results reinforce the urgent need to develop alternative control strategies to complement those already existing. Key words : Malaria, Morbidity, Vector control, Resistance, Burkina Faso.

Background: A better understanding of malaria transmission at a local scale is essential for developing and implementing effective control strategies. In the frame of a randomized control trial, we aimed to provide an updated description of malaria transmission in the Korhogo area, northern Côte d'Ivoire, and to get baseline data for the trial. Methods:We performed Human Landing Collections in 26 villages in the Korhogo area during the rainy season