Use of Anopheles salivary biomarker to assess seasonal variation of human exposure to Anopheles bites in children living near rubber and oil palm cultivations in Côte d'Ivoire

Abstract

Environmental changes related to agricultural practices and activities can impact malaria transmission. In the objective to evaluate this impact on the human-vector contact, the level of human exposure to Anopheles vector bites was assess by an immuno-epidemiological indicator based on the assessment of the human IgG antibody response to the Anopheles gambiae gSG6-P1 salivary peptide, previously validated as a pertinent biomarker.Two cross-sectional surveys were carried out in the dry and rainy season in three villages with intensive agricultural plantations (N'Zikro with rubber cultivation, Ehania-V5 and Ehania-V1 with palm oil exploitation) and in a control village without plantations (Ayébo). Overall, 775 blood samples were collected in filter papers from children aged 1 to 14 years-old for immunological analysis by ELISA. The IgG levels to the gSG6-P1 salivary peptide significantly differed between studied villages both in the dry and the rainy seasons (P < 0.0001) and were higher in agricultural villages compared to the control area. In particular, the level of specific IgG in Ehania-V5, located in the heart of palm oil plantations, was higher compared to other agricultural villages. Interestingly, the level of specific IgG levels classically increased between the dry and the rainy season in the control village (P < 0.0001) whereas it remained high in the dry season as observed in the rainy season in agricultural villages.The present study indicated that rubber and oil palm plantations could maintain a high level of human exposure to Anopheles bites during both the dry and rainy seasons. These agricultural activities could therefore represent a permanent factor of malaria transmission risk.

Factors Associated With Human IgG Antibody Response to Anopheles albimanus Salivary Gland Extract, Artibonite Department, Haiti, 2017

“…gambiae gSG6 single target [10][11][12][19][20][21][22]. Various groups have also examined the relationship between environmental factors and mosquito salivary antigens in other mosquito species or other anopheline salivary components [7,23,24]. As anopheline mosquitoes are ubiquitous throughout Haiti, there would be no reason to assume anyone enrolled in this current study would have not been bitten by these mosquitoes at some point in their life, and attempts were not made to dichotomize the anti-SGE IgG assay signal into seropositive and seronegative categories.…”

Geospatial joint modeling of vector and parasite serology to microstratify malaria transmission

“…[reported in some studies from the GMS ( 47 – 49 )]. The boosting and decay dynamics of these antibodies in response to Anopheles biting exposure will also contribute to seasonal patterns but are yet to be fully elucidated—most studies investigating seasonality are biannual or at most quarterly ( 50 – 52 ) and our study of 15 mo duration could not capture the dynamics of anti- Anopheles salivary antibodies in response to repeated seasonal changes in Anopheles biting exposure. We were unable to model the longitudinal dynamics of these antibodies in a spatiotemporal framework in the present study due to low monthly testing rates in large numbers of villages; however, future studies could further explore these longitudinal and potentially lagged dynamics with more temporally resolved data.…”

Human Antibody Response to Dengue Vector Salivary Proteins: A Mini-Review

“…Studies that target human exposure to Aedes saliva mainly focus on the environmental parameters to determine the density and fluctuation of Aedes vectors. It has been demonstrated that rainfall density and geographical phenomena can intensely impact the vector density and population distribution (4,(21)(22). As such, the evaluation of human contact with vector saliva during the wet season is more advantageous in comparison to other seasons.…”