The fast urbanization of large African cities, the anarchic occupation of urban space and various socioeconomic conditions have major implications in the epidemiology of urban malaria. The presence of shallow waters, rice cultivation and gardening in an urban environment could lead to variation in malaria transmission [
1]. In Bouaké, the second largest city of Côte d’Ivoire, several shallows have been transformed for rice farming and vegetable farming. This factor increases mosquito proliferation, in particular
Anopheles gambiae, the major malaria vector in Africa, which is adapted to this urban environment and ensures a continuous transmission of malaria in several of the city’s neighbourhoods [
2]. The presence of
An. gambiae mosquitoes depends on local conditions, which explain the considerable variability of malaria distribution. Malaria transmission may vary from one region, neighbourhood and household to another, reflecting the concept of transmission hot spots [
1,
3‐
5]. Even though malaria transmission in urban settings is generally considered low compared to rural areas, city dwellers could be considered at high risk of severe malaria because of their low acquired immunity specific to malaria, highlighting the particular health problem of urban malaria [
6,
7].
The evaluation of malaria transmission is currently based on entomological methods (human-landing catch) and on parasitological assessments in human populations. However, these methods are labour-intensive and difficult to sustain on a large scale, especially when transmission and exposure levels are low (dry season, high altitude, urban settings or after vector control) [
8,
9]. The entomological methods commonly used to assess human exposure to mosquito bites do not provide a measure of the individual exposure in a given area. In addition, these methods inevitably increase the hazard of the participants’ exposure to mosquito-borne infections and, therefore, cannot be used in children [
10,
11].
To improve the evaluation of malaria transmission/exposure according to the World Health Organization (WHO) recommendations, much effort is being made to develop new indicators and methods at the individual level. Over the past few decades, several studies have shown that the measurement in human populations of antibody (Ab) responses to saliva molecules of vector insect was an adequate method to assess the human exposure level to vector bites and the risk of vector-borne disease [
12,
13]. Specifically, the gSG6-P1 peptide (
An. gambiae Salivary Gland Protein-6 peptide 1) of
Anopheles saliva has been identified as a pertinent biomarker of
Anopheles bites [
14]. This salivary peptide is specific to the
Anopheles genus, antigenic, easy to synthesize and highly conserved between
Anopheles mosquitoes [
14]. In particular, the human IgG response to the gSG6-P1 peptide was especially relevant as a biomarker in a context of low exposure to
Anopheles bites, for example in urban settings and during the dry season [
15,
16]. In one study, carried out in northern Senegal in 2013, this salivary biomarker was used to observe a considerable heterogeneity of human exposure to
Anopheles between neighbouring villages in a low-transmission setting [
16]. In addition, this biomarker was recently used to identify hotspots of malaria transmission in severe areas in Thailand [
17]. It could therefore be applied to malaria surveillance and control (i) by assessing the level of heterogeneity of human exposure to
Anopheles bites [
18] and (ii) by evaluating the efficacy (Phase 3 study) and the effectiveness (operational level, post-implementation) of vector control strategies [
19,
20]. Indeed, in low urban transmission areas in Dakar, Senegal, it was shown that human IgG responses to the gSG6-P1 peptide could be, at both the population and individual levels, a credible new alternative tool to assess the heterogeneity of exposure levels to
Anopheles bites and malaria risk [
15]. Moreover, by proving the usefulness of this biomarker for assessing the effectiveness of anti-malaria vector control in populations, it was shown that this biomarker could be used as a potential alternative to the standard entomological methods, especially in low-endemic areas and urban settings [
20]. Previous results in the same areas, using this immunological biomarker, indicated that human exposure to
Anopheles bites remained similar in both urban and rural areas, whatever the season [
21]. Surprisingly, urban populations could therefore be as highly exposed to
Anopheles bites as populations living in rural areas.
The major aim of the present study was, therefore, to explore the heterogeneity of human exposure to Anopheles bites in different neighbourhoods in Bouaké, Côte d’Ivoire, using the An. gambiae salivary biomarker (gSG6-P1). Additionally, in this context of urban exposure to the Anopheles vector, the potential impact of the declared use of insecticide-treated nets (ITNs) was evaluated on human–vector contact.