Characterization of human exposure to Anopheles and Aedes bites using antibody-based biomarkers in rural zone of Cameroon

Abstract

Malaria and Aedes-borne diseases remain major causes of mortality, morbidity, and disability in most developing countries. Surveillance of transmission patterns associated with vector control remains strategic for combating these diseases. Due to the limitions of current surveillance tools used to assess human exposure to mosquito bites, human antibody (Ab) responses to salivary peptides from Anopheles (gSG6-P1) and Aedes (Nterm-34kDa) are increasingly being used to measure direct human-Anopheles or Aedes contact. This study reports on the assessment of Human IgG Ab responses to gSG6-P1 and Nterm–34-kDa salivary peptides as biomarkers to track exposure to Anopheles and Aedes bites, in rural localities of Cameroon. Blood samples were collected between October and November 2022 from 173 individuals residing in four villages: Njombe, Kekem, Belabo, and Ouami. Sociodemographic characteristics and information regarding Long Lasting Insecticide Net (LLIN) ownership, use, and net characteristics were recorded using a questionnaire. The measurement of human IgG levels to gSG6-P1 and Nterm-34kDa peptides was conducted in blood samples using ELISA. The levels of IgG responses to Anopheles gSG6-P1 and Aedes Nterm-34kDa salivary peptides varied significantly across villages (all p<0.05). IgG responses to Anopheles gSG6-P1 were higher in Njombe compared to Belabo and Ouami (all p<0.01), while IgG responses to Aedes Nterm-34kDa were higher in Kekem compared to the other villages (all p<0.0001). Aweak correlation was observed between IgG responses to Anopheles and Aedes salivary peptides (Spearman r = 0.2689, p = 0.0003). However, the median level of IgG to Anopheles gSG6-P1 was higher than IgG to Aedes Nterm-34kDa in Njombé, Belabo, and Ouami. Individuals not using their LLIN, those using damaged bed nets, and those who reported vegetation around their houses developed higher IgG responses to gSG6-P1 and Nterm–34 kDa compared to those who did not (all p<0.05). The immune-epidemiological biomarkers have shown promising potential as indicators for monitoring human exposure to various mosquito bites and their heterogeneity in the same site. However, additional research is needed to validate the efficacy of this technique for surveillance purposes and to assess the effectiveness of vector control interventions.

Introduction

Anopheles and Aedes mosquitoes are vectors of significant infectious diseases including malaria, dengue, chikungunya, and yellow fever. Globally, malaria affect over 240 million poeple and cause more than 600,000 deaths annually [1]. In Cameroon, the prevalence of this disease ranges from 24 to 30%, with children under 5 years and pregnant women being the most affected groups [1]. Among arboviruses, dengue fever (DF) is a critical arboviral disease affecting approximately 3.9 billion people in 128 countries, representing 40–50% of the global population [2]. Approximatively, 400 million cases of DF occur each year, leading to 20 to 25,000 deaths, affecting predominantly children in developing nations [3]. Over the past decade, several epidemics of dengue, chikungunya, and yellow fever outbreaks have been reported in sub-Saharan Africa [4–6]. In Cameroon, numerous cases of dengue, chikungunya, and yellow fever have been frequently reported since 2006 [5,7–9].

In order to advance towards the elimination of malaria and arboviral diseases, surveillance activities are crucial to inform policy and for evidence-based decision-making. Sampling techniques commonly used to measure exposure to Anopheles and Aedes bites include mosquito collection using various methods or human landing catches. While these methods provide valuable information to monitor vector-human interactions, they have limitations such as dexterity at the individual level, cost, logistical challenges, and ethical concerns [10–12]. These limitations imply that they may not be effective in all epidemiological contexts and could introduce certain biases. Additional tools, such as biomarkers of human exposure to Anopheles [13] and Aedes bites [14], have been developed and validated to quantitatively and individually measure the level of exposure of human populations to malaria and arboviral vectors. These biomarkers are based on assessing the level of IgG antibody (Ab) response to proteins/peptides from mosquito saliva. Studies conducted so far indicate that human IgG levels to Aedes Nterm -34Da protein and Anopheles gSG6-P1 are specific biomarkers highly conserved between species and are particularly relevant for monitoring exposure to arboviral and malaria vectors, even in a context of low exposure to these mosquito bites [15–18].

The aim of the present study was to explore the heterogeneity of human exposure to both Aedes and Anopheles bites in four rural settings in Cameroon by using both biomarkers and the potential impact of sociodemographic factors.

Material and methods

Study sites

A cross-sectional study was conducted from October to November 2022 in four localities: Ouami, Belabo, Kékem, and Njombé (Fig 1). Ouami (5°16’60”N, 13°34’60” E) and Belabo (4°56’00”N, 13°18’00” E) are situated in the East Forest region of Cameroon near the Lom-Pangar hydroelectric dam along the Sanaga river. The area is known for its floodplains extensively used for fishing. The climate is equatorial with four seasons: a long dry season from mid-November to mid-March, a short rainy season from mid-March to June, a short dry season from July to August, and a long rainy season from September to mid-November. Kekem (5°10’00”N, 10°02’00”E) is located in the West Region at the base of the mountains. The climate in this area is characterized by two seasons: a dry season from November to March and a rainy season from April to October. Njombé (4°64′65″ N, 9°67′83″ E) is situated in the Littoral Region, characterized by a nine-month long rainy season (March to November) and a short dry season (December to February).

[Figure omitted. See PDF.]

Ethical clearance

The study received approval from the National Human Health Research Ethics Committee of Cameroon under No. 2020/04/1209/CE/CNERSH/SP, and administrative authorization was obtained from the local divisional officer. Oral informed consent was obtained from adult participants, as well as parents or guardians of children under 18 years of age. This verbal agreement was noted on each individual survey form and was approved by the Institutional Review Board. Participants included in the study had resided in each locality for at least one month. In appreciation of their voluntary participation, individuals showing symptoms of common illnesses were provided with appropriate medications.

Data collection

The selection of households was done randomly, and interviews were carried out in each household using a structured questionnaire to collect socio-demographic information, age, gender, ownership, and utilization of LLINs. The presence of vegetation around the house was recorded through visual inspection. If they agreed to participate, up to three individuals were sampled from each household. Blood samples were collected on Whatman 3 MM paper using the dried blood spot (DBS) technique and stored at 4°C until needed.

Salivary peptides gSG6-P1 and Nterm–34-kDa.

Synthetic forms of the antigenic peptides gSG6-P1 (Catalogue number GPS_1216, Genepep, Saint Jean de Vedas, France) and Nterm-34–kDa (Catalogue number GPS_2958, Genepep, Saint Jean de Vedas, France) were each resuspended in ultra-filtered water and stored at a concentration of 1 mg/mL at -20°C until use.

Assessment of human IgG antibody levels against gSG6-P1 and Nterm–34-kDa.

DBSs (diameter, 0.8 cm) were eluted as previously described [14]. ELISA assays were carried out on DBS eluates separately to assess IgG responses to gSG6-P1 and Nterm–34-kDa salivary antigens following established protocols [14,16]. Briefly, Maxisorp plates (Nunc, Roskilde, Denmark) were coated with 20 μg/ml of Nterm–34-kDa or gSG6-P1 and incubated at 37°C for 2 hours and 30 minutes. The plates were then blocked for 1 hour at room temperature using 300 μL of protein-free blocking buffer (Thermoscientific, Rockford, United States). Eluates diluted at 1/20 in PBS-Tween 1% were added and incubated overnight at +4°C. Biotinylated mouse anti-human IgG (BD Pharmingen, San Diego CA, USA) was subsequently added at a concentration of 1/1000 in PBS-Tween 1% to detect bound human IgG, followed by the addition of streptavidin-conjugated peroxidase (GE Healthcare, Orsay, France) at 1/1000 in PBS-Tween 1%. ABTS (2,2’-azino-bis (3 ethylbenzthiazoline 6-sulfonic) diammonium acid; Sigma, St Louis, MO, USA) was used as the substrate, and optical densities (ODs) were measured at 405 nm after 2 hours of development. Each sample was assayed in duplicate wells containing salivary peptide and in a well without antigen to account for non-specific reactions. The individual results were quantified as the ΔOD value: ΔOD = ODx − ODn, where ODx represents the mean of the individual OD values in both wells with salivary antigen and ODn represents the individual OD value in a blank well without antigen. The reproducibility between ELISA plates has been verified by using 3 positive controls (low, medium, high of specific IgG levels) in each plate to monitor plate to plate variations. However, the study faced difficulty in using a negative control to calculate the cut-off due to challenge in obtaining serum from unexposed individuals in Africa.

Statistical analysis.

All data were analyzed using Graph Pad Prism^® software (Graph Pad Software, San Diego, California, United States) version 9. Spearman correlation analysis was employed to compare IgG antibody levels against Anopheles and Aedes salivary antigens. After verifying that the data did not follow a Gaussian distribution or Normality test, the comparison between two different groups (quantitative variables) was conducted using the non-parametric Mann-Whitney test. Comparisons between multiple groups were performed with the non-parametric Kruskal-Wallis tests (for independent series). Dunn’s post-test was utilized for multiple paired comparisons between villages. Significance was determined at a p-value < 0.05.

Results

Characteristics of the study population by village

A total of 173 study participants were enrolled in the four villages: 55 individuals in Njombé, 40 in Kekem, 51 in Belabo, and 27 in Ouami (Table 1). Participants were evenly distributed among four age groups (0 to 5 years, 6 to 10 years, 11 to 15 years, and over 15 years). However, there was a slight underrepresentation of children aged 11–15 years in Njombé and those aged 0–5 years in Belabo. The sex ratio favored females (2:1) in Njombe, while it favored males in Ouami (Table 1). The majority of participants (>90%) owned a LLIN, but not all (41.8–85%) reported using them. Most of the nets were damaged with holes in Njombé (69.8%), Belabo (71.7%), and Ouami (90%). Njombé village had the lowest number of participants using LLINs (41.8%) despite a high ownership rate. Kekem recorded the highest number of participants owning (97.5%) and using (85%) LLINs, and the difference was significant after a group comparison with other sites (P = 0.006; P = 0.0001 for those two variables respectively). In all the study villages, LLINs were used mostly every night. Regarding the presence of vegetation around the houses, in all localities, the majority of houses had vegetation around them except in Belabo (Table 1).

[Figure omitted. See PDF.]

IgG levels against Anopheles and Aedes salivary peptides

Globally, the specific IgG levels ranged from 0.011 and 1.073 for the Nterm-34-kDa peptide and from 0.005 to 1.185 for the gSG6-P1 peptide. The comparison for both peptides was conducted by village of residence, and, except for Kekem village where there was no significant difference between IgG responses to both salivary peptides, IgG responses towards Anopheles mosquito bites were higher than those towards Aedes mosquitoes in Njombé, Belabo, and Ouami (p<0.0001) (Fig 2). We used Kruskal-Wallis test when analyzing exposure to Anopheles and Aedes bites across villages and both IgG levels to the gSG6-P1 and Nterm-34kDa varied significantly. IgG levels to the gSG6-P1 were significantly higher in Njombé compared to Kekem, Belabo, and Ouami (p = 0.01), while IgG levels to the Nterm-34kDa were higher in Kekem compared to the other three other villages (p<0.0001) (Fig 2 and Table 2).

[Figure omitted. See PDF.]

Triangular and round dots indicate individual IgG responses to gSG6-P1 and Nterm-34kDa salivary peptides, respectively, while red bars represent median values in each village. Statistically significant differences between all paired antibody levels (Wilcoxon paired test) are indicated. An. = Anopheles; Ae. = Aedes.

[Figure omitted. See PDF.]

Mann-Whitney test was used when there are two groups and Kruskal-Wallis test when there are more than two groups.

Sociodemographic factors influencing exposure to Anopheles and Aedes

IgG levels specific to Anopheles gSG6-P1 and Aedes Nterm–34 kDa salivary peptides were analyzed according to the village of residence, gender, age groups, bed net ownership, bed net use, bed net condition, and presence of vegetation around the house (Table 2). Age groups, gender, and bed net ownership did not appear to influence the IgG levels to Anopheles and Aedes salivary peptides in the study area (all p>0.05). However, bed net use, bed net condition, and the presence of vegetation around the house significantly impacted the IgG responses to Anopheles and Aedes salivary peptides. Participants who reported using their bed nets had notably lower median IgG responses to the Anopheles gSG6-P1 (p<0.0076) than those who reported not using them. Surprisingly, the opposite effect was observed for Aedes exposure, as participants who reported using their bed nets had significantly higher median IgG responses to the Aedes Nterm -34 kDa (p<0.0005) than those who reported not using their bed nets. This situation was specific to Njombé (p = 0.0069) (S1 File).xs

As anticipated, participants who reported using bed nets with holes or those with noted vegetation around their homes exhibited significantly higher median levels of IgG towards both Anopheles (median = 0.269 and 0.269, respectively) and Aedes (median = 0.204 and 0.157, respectively) compared to those who did not (p<0.05) (Table 2).

For the use of mosquito nets in poor condition (with holes) versus good condition (no holes) per village, the difference was significant only for exposure to Anopheles bites in Bélabo (median good condition = 0.158, median poor condition = 0.438, p = 0.005). However, this difference was not significant for exposure to Aedes (Kekem: p = 0.860; Bélabo: p = 0.099; Njombe: p = 0.966; Ouami: p = 0.947; Ouami: p = 0.937) and Anopheles (Kekem: p = 0.274; Njombe: p = 0.719; Ouami: p = 0.937) in the other three other sites.

Concerning the presence of vegetation around households per village, there was no significant difference in the median level of IgG responses to the Anopheles peptide (Kekem: p = 0.793; Belabo: p = 0.221; Njombe: p = 0.442; Ouami: p = 0.999) and Aedes peptide (Kekem: p = 0.170; Belabo: p = 0.145; Njombe: p = 0.609; Ouami: p = 0.860) across all sites.

Correlation between IgG levels against Anopheles (gSG6-P1) and Aedes (Nterm-34kDa) salivary antigens

We further investigated the correlation between IgG levels against Anopheles (gSG6-P1) and Aedes (Nterm-34kDa) salivary antigens using blood samples from the same individuals. A weak but statistically significant correlation was observed (Spearman r = 0.2689 (95% CI: 0.1203–0.4057), p = 0.0003) (Fig 3). Upon village-specific analysis, the correlation of IgG levels against Anopheles (gSG6-P1) and Aedes (Nterm-34kDa) salivary antigens was significant within the same individuals in the villages of Bélabo (Spearman r = 0.450, CI (0.190–0.650); p = 0.001) and Ouami (Spearman r = 0.494, CI (0.129–0.741), while it was not significant in Kekem (Spearman r = 0.220, CI (-0.108–0.504); p = 0.173) and Njombé (Spearman r = 0.028, CI (-0.247–0.298); p = 0.840).

[Figure omitted. See PDF.]

Discussion

The study assessed IgG responses against Anopheles gSG6-P1 and Aedes Nterm-34 kDa salivary peptides, which serve as indicators of human exposure to Anopheles and Aedes mosquito bites, in individuals residing in four distinct rural areas in Cameroon. The findings revealed varying patterns of human exposure to bites from both Anopheles and Aedes mosquitoes. In Njombé, Bélabo, and Ouami, the median IgG responses to Anopheles gSG6-P1 were notably higher than those to Aedes Nterm-34kDa, whereas in Kekem, the median IgG levels to Nterm-34kDa were higher compared to the other three villages. This diversity in human exposure to Anopheles and Aedes bites across villages may stem from different ecological and environmental factors. Factors such as the presence of various habitat types like man-made habitats, agricultural activities, proximity to water bodies, water storage containers, varied climatic conditions, and different human behaviours were identified as contributing to the creation of suitable habitats for different mosquito species. These factors could increase the risk of human exposure to both Anopheles and Aedes mosquito bites [19,20]. Previous studies in Cameroon using the gSG-P1 biomarker have shown differences in biomarker expression levels between mainland and island populations, indicating varying transmission risks across the country [21]. Similar observations were reported in previous studies in Senegal [20]. Aedes mosquitoes, particularly Ae. albopictus and Ae. aegypti, are prevalent in many regions in the south of Cameroon [22,23]. The lower exposure to Aedes mosquito bites in Njombé, Bélabo, and Ouami may be attributed to seasonal fluctuations. Conversely, the higher exposure to both Aedes and Anopheles mosquitoes in Kekem could result from a favourable environment for the proliferation of both vectors such as the exploitation of lowland areas for the practice of seasonal gardening activities, widespread presence of water storage containers in households for rainwater collection, and the abundance of old tires serving various purposes or left in the environment.

Regarding the distribution of Anopheles species, previous studies have shown the presence of both An. gambiae ss and An. coluzzii in Belabo and Ouami, while An. coluzzi and An. gambiae ss were identified as the predominant species in Njombe and Kekem respectively [24,25].

The potential influence of sociodemographic characteristics, human behavior, and living environment was compared to the level of exposure to Anopheles and Aedes bites. Analyses of IgG responses against Anopheles and Aedes salivary peptides showed no significant differences according to age, gender, and possession of LLINs. The study findings do not align with previous reports which indicated an increase in exposure to mosquito bites with age in Senegal [13,20,26].

Individual IgG responses to Anopheles gSG6-P1 and Aedes Nterm-34kDa salivary peptides were also analysed based on LLIN ownership, usage rate, and net physical status. This analysis revealed no significant difference in IgG responses to both salivary peptides with bed net ownership which could be associated with the high ownership rate of bed nets in the country. However, the frequency of bed net usage and the physical condition of the nets (presence of holes) were significantly associated with IgG responses to Anopheles gSG6-P1 and Aedes Nterm-34kDa salivary peptides. Individuals who reported sleeping under bed nets every night had notably lower IgG responses to Anopheles gSG6-P1, while bed net usage did not correlate with IgG responses to Aedes Nterm-34-kDa. This finding aligns with previous research [18,21,26,27]. The levels of specific IgG in the participants varied significantly based on the physical condition of the LLINs, with higher levels observed in individuals using damaged LLINs compared to those using intact ones. Similar trends were reported in prior studies, where individuals using coils or spray bombs had lower IgG responses to gSG6-P1 compared to non-users [21]. This pattern is consistent with research from Benin [28] and Ivory coast [18], demonstrating that the use of LLINs in good condition is associated with reduced exposure to Anopheles mosquito bites. These findings highlight the relevance and sensitivity of this biomarker not only for assessing LLIN efficacy but also for evaluating the physical integrity of LLINs, as previously shown by Noukpo in Benin [28].

The presence of vegetation around houses was found to increase exposure to Aedes bites. People living close to vegetation had higher levels of IgG responses to gSG6-P1 and Nterm–34 kDa compared to those living in houses with little vegetation around their home. This result was consistent with findings from various studies conducted elsewhere [20,29].

Since the study was conducted in October during the rainy season, it is possible that seasonal fluctuations were not fully captured, warranting further attention. Additionally, several other individual factors such as migration of individuals across villages, use of other vector control strategies (e.g., coils, indoor residual spraying), genetic predispositions, and levels of education/awareness of malaria control strategies, which could potentially influence the immunological results of our study have not been assessed. Future studies may be needed to evaluate their potential impacts.

The study underscores the importance of integrating various sampling methods to enhance the surveillance of both malaria and arbovirus vectors. Additionally, it highlights the necessity of implementing an integrated vector management program that considers the spatial heterogeneity of transmission risk to maximize the effectiveness of interventions in the field.

Conclusion

Human antibody responses towards Anopheles gSG6-P1 and Aedes Nterm-34kDa salivary peptides varied depending on the village of residence, bed net usage and condition, and the presence of vegetation around houses. While more individuals were exposed to Anopheles bites compared to Aedes bites, those highly exposed to Anopheles are not necessarily highly exposed to Aedes mosquitoes, and vice versa, suggesting the heterogeneity of exposure, at the individual level, to major mosquito species in specific settings. These immunological tools seem to be therefore valuable for informing mosquito-borne disease control programs for evaluating vector control strategies on human-vector contact and adjusting control strategies based on exposure variation. However, standardized and optimized methods for assessing these specific antibody-based biomarkers (e.g., through the development of Rapid Diagnostic Tests) are essential the operational utilization of these tools by vector control and surveillance programs.

Supporting information

S1 File. Comparison of gSG6-P1 antibody levels and Nterm-34kDa antibody levels according to bed net use by village.

Red bars represent median values in each village.

https://doi.org/10.1371/journal.pone.0314709.s001

S2 File. Data base with Delda DO for Anopheles and Aedes.

https://doi.org/10.1371/journal.pone.0314709.s002

(XLSX)

Acknowledgments

We are grateful to the administrative and traditional authorities, to Chi Nji Princewill and the population of Njombé, Kékem, Belabo and Ouami for their participation in the study.

References

1. 1. World Health Organization. (WHO). World malaria report 2023. Geneva: cdn.who.int.

2. 2. Brady OJ, Gething PW, Bhatt S, Messina JP, Brownstein JS, Hoen AG, et al. Refining the Global Spatial Limits of Dengue Virus Transmission by Evidence-Based Consensus. PLOS Neglected Tropical Diseases. 2012;6: e1760. pmid:22880140

* View Article

* PubMed/NCBI

* Google Scholar

3. 3. Bhatt S, Gething PW, Brady OJ, Messina JP, Farlow AW, Moyes CL, et al. The global distribution and burden of dengue. Nature. 2013;496: 504–507. pmid:23563266

* View Article

* PubMed/NCBI

* Google Scholar

4. 4. Manigart O, Ouedraogo I, Ouedraogo HS, Sow A, Lokossou VK. Dengue epidemic in Burkina Faso: how can the response improve? The Lancet. 2024;403: 434–435. pmid:38272051

* View Article

* PubMed/NCBI

* Google Scholar

5. 5. Simo Tchetgna H, Sado Yousseu F, Kamgang B, Tedjou A, McCall PJ, Wondji CS. Concurrent circulation of dengue serotype 1, 2 and 3 among acute febrile patients in Cameroon. PLoS Negl Trop Dis. 2021;15: e0009860. pmid:34695135

* View Article

* PubMed/NCBI

* Google Scholar

6. 6. Vairo F, Aimè Coussoud-Mavoungou MP, Ntoumi F, Castilletti C, Kitembo L, Haider N, et al. Chikungunya Outbreak in the Republic of the Congo, 2019—Epidemiological, Virological and Entomological Findings of a South-North Multidisciplinary Taskforce Investigation. Viruses. 2020;12: 1020. pmid:32933109

* View Article

* PubMed/NCBI

* Google Scholar

7. 7. Nana-Ndjangwo SM, Djiappi-Tchamen B, Mony R, Demanou M, Keumezeu-Tsafack J, Bamou R, et al. Assessment of Dengue and Chikungunya Infections among Febrile Patients Visiting Four Healthcare Centres in Yaoundé and Dizangué, Cameroon. Viruses. 2022;14: 2127. pmid:36298682

* View Article

* PubMed/NCBI

* Google Scholar

8. 8. Tchuandom SB, Tchadji JC, Tchouangueu TF, Biloa MZ, Atabonkeng EP, Fumba MIM, et al. A cross-sectional study of acute dengue infection in paediatric clinics in Cameroon. BMC Public Health. 2019;19: 958. pmid:31319834

* View Article

* PubMed/NCBI

* Google Scholar

9. 9. Yousseu FBS, Nemg FBS, Ngouanet SA, Mekanda FMO, Demanou M. Detection and serotyping of dengue viruses in febrile patients consulting at the New-Bell District Hospital in Douala, Cameroon. PLoS One. 2018;13: e0204143. pmid:30281633

* View Article

* PubMed/NCBI

* Google Scholar

10. 10. Huho B, Briët O, Seyoum A, Sikaala C, Bayoh N, Gimnig J, et al. Consistently high estimates for the proportion of human exposure to malaria vector populations occurring indoors in rural Africa. Int J Epidemiol. 2013;42: 235–247. pmid:23396849

* View Article

* PubMed/NCBI

* Google Scholar

11. 11. Lima JBP, Rosa-Freitas MG, Rodovalho CM, Santos F, Lourenço-de-Oliveira R. Is there an efficient trap or collection method for sampling Anopheles darlingi and other malaria vectors that can describe the essential parameters affecting transmission dynamics as effectively as human landing catches?—A Review. Mem Inst Oswaldo Cruz. 2014;109: 685–705. pmid:25185008

* View Article

* PubMed/NCBI

* Google Scholar

12. 12. Smith T, Killeen G, Lengeler C, Tanner M. Relationships between the outcome of Plasmodium falciparum infection and the intensity of transmission in Africa. Am J Trop Med Hyg. 2004;71: 80–86. pmid:15331822

* View Article

* PubMed/NCBI

* Google Scholar

13. 13. Poinsignon A, Cornelie S, Ba F, Boulanger D, Sow C, Rossignol M, et al. Human IgG response to a salivary peptide, gSG6-P1, as a new immuno-epidemiological tool for evaluating low-level exposure to Anopheles bites. Malar J. 2009;8: 198. pmid:19674487

* View Article

* PubMed/NCBI

* Google Scholar

14. 14. Elanga Ndille E, Doucoure S, Damien G, Mouchet F, Drame PM, Cornelie S, et al. First attempt to validate human IgG antibody response to Nterm-34kDa salivary peptide as biomarker for evaluating exposure to Aedes aegypti bites. PLoS Negl Trop Dis. 2012;6: e1905. pmid:23166852

* View Article

* PubMed/NCBI

* Google Scholar

15. 15. Ndo C, Elanga-Ndille E, Cheteug G, Metitsi RD, Wanji S, Moukoko CEE. IgG antibody responses to Anopheles gambiae gSG6-P1 salivary peptide are induced in human populations exposed to secondary malaria vectors in forest areas in Cameroon. PLoS One. 2022;17: e0276991. pmid:36355922

* View Article

* PubMed/NCBI

* Google Scholar

16. 16. Sagna AB, Sarr JB, Gaayeb L, Drame PM, Ndiath MO, Senghor S, et al. gSG6-P1 salivary biomarker discriminates micro-geographical heterogeneity of human exposure to Anopheles bites in low and seasonal malaria areas. Parasites Vectors. 2013;6: 68. pmid:23497646

* View Article

* PubMed/NCBI

* Google Scholar

17. 17. Sagna AB, Yobo MC, Elanga Ndille E, Remoue F. New Immuno-Epidemiological Biomarker of Human Exposure to Aedes Vector Bites: From Concept to Applications. Tropical Medicine and Infectious Disease. 2018;3: 80. pmid:30274476

* View Article

* PubMed/NCBI

* Google Scholar

18. 18. Traoré DF, Sagna AB, Assi SB, Tchiekoi BN, Adja AM, Dagnogo M, et al. Operational Evaluation of the Effectiveness of Long-lasting Insecticidal Nets on Human-Vector Contact in an African Urban Malaria Context. Open Forum Infectious Diseases. 2021;8: ofaa635. pmid:33553475

* View Article

* PubMed/NCBI

* Google Scholar

19. 19. Antonio-Nkondjio C, Ndo C, Njiokou F, Bigoga JD, Awono-Ambene P, Etang J, et al. Review of malaria situation in Cameroon: technical viewpoint on challenges and prospects for disease elimination. Parasites & Vectors. 2019;12: 501. pmid:31655608

* View Article

* PubMed/NCBI

* Google Scholar

20. 20. Sagna AB, Kassié D, Couvray A, Adja AM, Hermann E, Riveau G, et al. Spatial Assessment of Contact Between Humans and Anopheles and Aedes Mosquitoes in a Medium-Sized African Urban Setting, Using Salivary Antibody-Based Biomarkers. J Infect Dis. 2019;220: 1199–1208. pmid:31152664

* View Article

* PubMed/NCBI

* Google Scholar

21. 21. Cheteug G, Elanga-Ndille E, Donkeu C, Ekoko W, Oloume M, Essangui E, et al. Preliminary validation of the use of IgG antibody response to Anopheles gSG6-p1 salivary peptide to assess human exposure to malaria vector bites in two endemic areas of Cameroon in Central Africa. PLoS One. 2020;15: e0242510. pmid:33382730

* View Article

* PubMed/NCBI

* Google Scholar

22. 22. Djiappi-Tchamen B, Nana-Ndjangwo MS, Nchoutpouen E, Makoudjou I, Ngangue-Siewe IN, Talipouo A, et al. Aedes Mosquito Surveillance Using Ovitraps, Sweep Nets, and Biogent Traps in the City of Yaoundé, Cameroon. Insects. 2022;13: 793. pmid:36135494

* View Article

* PubMed/NCBI

* Google Scholar

23. 23. Tedjou AN, Kamgang B, Yougang AP, Njiokou F, Wondji CS. Update on the geographical distribution and prevalence of Aedes aegypti and Aedes albopictus (Diptera: Culicidae), two major arbovirus vectors in Cameroon. PLoS Negl Trop Dis. 2019;13: e0007137. pmid:30883552

* View Article

* PubMed/NCBI

* Google Scholar

24. 24. Chouakeu NAK, Tchuinkam T, Bamou R, Bindamu MM, Talipouo A, Kopya E, et al. Malaria transmission pattern across the Sahelian, humid savanna, highland and forest eco-epidemiological settings in Cameroon. Malaria Journal. 2023;22: 116. pmid:37029411

* View Article

* PubMed/NCBI

* Google Scholar

25. 25. Ngangue-Siewe IN, Ndjeunia-Mbiakop P, Kala-Chouakeu NA, Bamou R, Talipouo A, Djamouko-Djonkam L, et al. Bendiocarb and Malathion Resistance in Two Major Malaria Vector Populations in Cameroon Is Associated with High Frequency of the G119S Mutation (Ace-1) and Overexpression of Detoxification Genes. Pathogens. 2022;11: 824. pmid:35894047

* View Article

* PubMed/NCBI

* Google Scholar

26. 26. Drame P, Poinsignon A, Marie A, Noukpo H, Doucoure S, Cornelie S, et al. New Salivary Biomarkers of Human Exposure to Malaria Vector Bites. 2013.

* View Article

* Google Scholar

27. 27. Ferede G, Tiruneh M, Abate E, Kassa WJ, Wondimeneh Y, Damtie D, et al. Distribution and larval breeding habitats of Aedes mosquito species in residential areas of northwest Ethiopia. Epidemiol Health. 2018;40: e2018015. pmid:29748457

* View Article

* PubMed/NCBI

* Google Scholar

28. 28. Noukpo MH, Damien GB, Elanga-N’Dille E, Sagna AB, Drame PM, Chaffa E, et al. Operational Assessment of Long-Lasting Insecticidal Nets by Using an Anopheles Salivary Biomarker of Human-Vector Contact. Am J Trop Med Hyg. 2016;95: 1376–1382. pmid:27928087

* View Article

* PubMed/NCBI

* Google Scholar

29. 29. Baragatti M, Fournet F, Henry M-C, Assi S, Ouedraogo H, Rogier C, et al. Social and environmental malaria risk factors in urban areas of Ouagadougou, Burkina Faso. Malaria Journal. 2009;8: 13. pmid:19144144

* View Article

* PubMed/NCBI

* Google Scholar

Citation: Ngangue-Siewe IN, Ndjeunia-Mbiakop P, Barembaye Sagna A, Mamadou Maïga A-A, Bamou R, Sanon A, et al. (2024) Characterization of human exposure to Anopheles and Aedes bites using antibody-based biomarkers in rural zone of Cameroon. PLoS ONE 19(12): e0314709. https://doi.org/10.1371/journal.pone.0314709

About the Authors:

Idriss Nasser Ngangue-Siewe

Roles: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Validation, Visualization, Writing – original draft

E-mail: [email protected] (INN-S); [email protected] (FR)

Affiliations: Faculty of Science, Department of Animal Biology and Physiology, The University of Douala, Douala, Cameroon, Malaria Research Laboratory, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, Cameroon, Laboratory of Fundamental and Applied Entomology, University Joseph Ki-Zerbo, Ouagadougou, Burkina Faso

ORICD: https://orcid.org/0000-0001-9578-6365

Paulette Ndjeunia-Mbiakop

Roles: Investigation, Methodology, Validation, Writing – review & editing

Affiliations: Malaria Research Laboratory, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, Cameroon, Faculty of Science, Department of Animal Biology and Physiology, The University of Yaoundé, Yaoundé, Cameroon

André Barembaye Sagna

Roles: Data curation, Formal analysis, Methodology, Validation, Visualization, Writing – review & editing

Affiliation: Institut de Recherche Pour le Développement (IRD), MIVEGEC Unit, University of Montpellier, IRD, CNRS, DR Occitanie, Montpellier, France

ORICD: https://orcid.org/0000-0001-8586-792X

Abdoul-Aziz Mamadou Maïga

Roles: Formal analysis, Methodology, Writing – review & editing

Affiliation: Laboratory of Fundamental and Applied Entomology, University Joseph Ki-Zerbo, Ouagadougou, Burkina Faso

Roland Bamou

Roles: Validation, Visualization, Writing – review & editing

Affiliations: Malaria Research Laboratory, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, Cameroon, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institute of Health (NIH), Rockville, Maryland, United States of America

Antoine Sanon

Roles: Writing – review & editing

Affiliation: Laboratory of Fundamental and Applied Entomology, University Joseph Ki-Zerbo, Ouagadougou, Burkina Faso

Jeannette Tombi

Roles: Validation, Writing – review & editing

Affiliation: Faculty of Science, Department of Animal Biology and Physiology, The University of Yaoundé, Yaoundé, Cameroon

Jean Arthur Mbida Mbida

Roles: Supervision, Validation, Writing – review & editing

Affiliation: Faculty of Science, Department of Animal Biology and Physiology, The University of Douala, Douala, Cameroon

Christophe Antonio-Nkondjio

Roles: Conceptualization, Funding acquisition, Supervision, Validation, Writing – review & editing

Affiliations: Malaria Research Laboratory, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, Cameroon, Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom

Franck Remoue

Roles: Conceptualization, Data curation, Formal analysis, Methodology, Validation, Visualization, Writing – review & editing

E-mail: [email protected] (INN-S); [email protected] (FR)

Affiliation: Institut de Recherche Pour le Développement (IRD), MIVEGEC Unit, University of Montpellier, IRD, CNRS, DR Occitanie, Montpellier, France

Athanase Badolo

Roles: Conceptualization, Supervision, Validation, Visualization, Writing – review & editing

Affiliation: Laboratory of Fundamental and Applied Entomology, University Joseph Ki-Zerbo, Ouagadougou, Burkina Faso

[/RAW_REF_TEXT]

References

1. World Health Organization. (WHO). World malaria report 2023. Geneva: cdn.who.int.

2. Brady OJ, Gething PW, Bhatt S, Messina JP, Brownstein JS, Hoen AG, et al. Refining the Global Spatial Limits of Dengue Virus Transmission by Evidence-Based Consensus. PLOS Neglected Tropical Diseases. 2012;6: e1760. pmid:22880140

3. Bhatt S, Gething PW, Brady OJ, Messina JP, Farlow AW, Moyes CL, et al. The global distribution and burden of dengue. Nature. 2013;496: 504–507. pmid:23563266

4. Manigart O, Ouedraogo I, Ouedraogo HS, Sow A, Lokossou VK. Dengue epidemic in Burkina Faso: how can the response improve? The Lancet. 2024;403: 434–435. pmid:38272051

5. Simo Tchetgna H, Sado Yousseu F, Kamgang B, Tedjou A, McCall PJ, Wondji CS. Concurrent circulation of dengue serotype 1, 2 and 3 among acute febrile patients in Cameroon. PLoS Negl Trop Dis. 2021;15: e0009860. pmid:34695135

6. Vairo F, Aimè Coussoud-Mavoungou MP, Ntoumi F, Castilletti C, Kitembo L, Haider N, et al. Chikungunya Outbreak in the Republic of the Congo, 2019—Epidemiological, Virological and Entomological Findings of a South-North Multidisciplinary Taskforce Investigation. Viruses. 2020;12: 1020. pmid:32933109

7. Nana-Ndjangwo SM, Djiappi-Tchamen B, Mony R, Demanou M, Keumezeu-Tsafack J, Bamou R, et al. Assessment of Dengue and Chikungunya Infections among Febrile Patients Visiting Four Healthcare Centres in Yaoundé and Dizangué, Cameroon. Viruses. 2022;14: 2127. pmid:36298682

8. Tchuandom SB, Tchadji JC, Tchouangueu TF, Biloa MZ, Atabonkeng EP, Fumba MIM, et al. A cross-sectional study of acute dengue infection in paediatric clinics in Cameroon. BMC Public Health. 2019;19: 958. pmid:31319834

9. Yousseu FBS, Nemg FBS, Ngouanet SA, Mekanda FMO, Demanou M. Detection and serotyping of dengue viruses in febrile patients consulting at the New-Bell District Hospital in Douala, Cameroon. PLoS One. 2018;13: e0204143. pmid:30281633

10. Huho B, Briët O, Seyoum A, Sikaala C, Bayoh N, Gimnig J, et al. Consistently high estimates for the proportion of human exposure to malaria vector populations occurring indoors in rural Africa. Int J Epidemiol. 2013;42: 235–247. pmid:23396849

11. Lima JBP, Rosa-Freitas MG, Rodovalho CM, Santos F, Lourenço-de-Oliveira R. Is there an efficient trap or collection method for sampling Anopheles darlingi and other malaria vectors that can describe the essential parameters affecting transmission dynamics as effectively as human landing catches?—A Review. Mem Inst Oswaldo Cruz. 2014;109: 685–705. pmid:25185008

12. Smith T, Killeen G, Lengeler C, Tanner M. Relationships between the outcome of Plasmodium falciparum infection and the intensity of transmission in Africa. Am J Trop Med Hyg. 2004;71: 80–86. pmid:15331822

13. Poinsignon A, Cornelie S, Ba F, Boulanger D, Sow C, Rossignol M, et al. Human IgG response to a salivary peptide, gSG6-P1, as a new immuno-epidemiological tool for evaluating low-level exposure to Anopheles bites. Malar J. 2009;8: 198. pmid:19674487

14. Elanga Ndille E, Doucoure S, Damien G, Mouchet F, Drame PM, Cornelie S, et al. First attempt to validate human IgG antibody response to Nterm-34kDa salivary peptide as biomarker for evaluating exposure to Aedes aegypti bites. PLoS Negl Trop Dis. 2012;6: e1905. pmid:23166852

15. Ndo C, Elanga-Ndille E, Cheteug G, Metitsi RD, Wanji S, Moukoko CEE. IgG antibody responses to Anopheles gambiae gSG6-P1 salivary peptide are induced in human populations exposed to secondary malaria vectors in forest areas in Cameroon. PLoS One. 2022;17: e0276991. pmid:36355922

16. Sagna AB, Sarr JB, Gaayeb L, Drame PM, Ndiath MO, Senghor S, et al. gSG6-P1 salivary biomarker discriminates micro-geographical heterogeneity of human exposure to Anopheles bites in low and seasonal malaria areas. Parasites Vectors. 2013;6: 68. pmid:23497646

17. Sagna AB, Yobo MC, Elanga Ndille E, Remoue F. New Immuno-Epidemiological Biomarker of Human Exposure to Aedes Vector Bites: From Concept to Applications. Tropical Medicine and Infectious Disease. 2018;3: 80. pmid:30274476

18. Traoré DF, Sagna AB, Assi SB, Tchiekoi BN, Adja AM, Dagnogo M, et al. Operational Evaluation of the Effectiveness of Long-lasting Insecticidal Nets on Human-Vector Contact in an African Urban Malaria Context. Open Forum Infectious Diseases. 2021;8: ofaa635. pmid:33553475

19. Antonio-Nkondjio C, Ndo C, Njiokou F, Bigoga JD, Awono-Ambene P, Etang J, et al. Review of malaria situation in Cameroon: technical viewpoint on challenges and prospects for disease elimination. Parasites & Vectors. 2019;12: 501. pmid:31655608

20. Sagna AB, Kassié D, Couvray A, Adja AM, Hermann E, Riveau G, et al. Spatial Assessment of Contact Between Humans and Anopheles and Aedes Mosquitoes in a Medium-Sized African Urban Setting, Using Salivary Antibody-Based Biomarkers. J Infect Dis. 2019;220: 1199–1208. pmid:31152664

21. Cheteug G, Elanga-Ndille E, Donkeu C, Ekoko W, Oloume M, Essangui E, et al. Preliminary validation of the use of IgG antibody response to Anopheles gSG6-p1 salivary peptide to assess human exposure to malaria vector bites in two endemic areas of Cameroon in Central Africa. PLoS One. 2020;15: e0242510. pmid:33382730

22. Djiappi-Tchamen B, Nana-Ndjangwo MS, Nchoutpouen E, Makoudjou I, Ngangue-Siewe IN, Talipouo A, et al. Aedes Mosquito Surveillance Using Ovitraps, Sweep Nets, and Biogent Traps in the City of Yaoundé, Cameroon. Insects. 2022;13: 793. pmid:36135494

23. Tedjou AN, Kamgang B, Yougang AP, Njiokou F, Wondji CS. Update on the geographical distribution and prevalence of Aedes aegypti and Aedes albopictus (Diptera: Culicidae), two major arbovirus vectors in Cameroon. PLoS Negl Trop Dis. 2019;13: e0007137. pmid:30883552

24. Chouakeu NAK, Tchuinkam T, Bamou R, Bindamu MM, Talipouo A, Kopya E, et al. Malaria transmission pattern across the Sahelian, humid savanna, highland and forest eco-epidemiological settings in Cameroon. Malaria Journal. 2023;22: 116. pmid:37029411

25. Ngangue-Siewe IN, Ndjeunia-Mbiakop P, Kala-Chouakeu NA, Bamou R, Talipouo A, Djamouko-Djonkam L, et al. Bendiocarb and Malathion Resistance in Two Major Malaria Vector Populations in Cameroon Is Associated with High Frequency of the G119S Mutation (Ace-1) and Overexpression of Detoxification Genes. Pathogens. 2022;11: 824. pmid:35894047

26. Drame P, Poinsignon A, Marie A, Noukpo H, Doucoure S, Cornelie S, et al. New Salivary Biomarkers of Human Exposure to Malaria Vector Bites. 2013.

27. Ferede G, Tiruneh M, Abate E, Kassa WJ, Wondimeneh Y, Damtie D, et al. Distribution and larval breeding habitats of Aedes mosquito species in residential areas of northwest Ethiopia. Epidemiol Health. 2018;40: e2018015. pmid:29748457

28. Noukpo MH, Damien GB, Elanga-N’Dille E, Sagna AB, Drame PM, Chaffa E, et al. Operational Assessment of Long-Lasting Insecticidal Nets by Using an Anopheles Salivary Biomarker of Human-Vector Contact. Am J Trop Med Hyg. 2016;95: 1376–1382. pmid:27928087

29. Baragatti M, Fournet F, Henry M-C, Assi S, Ouedraogo H, Rogier C, et al. Social and environmental malaria risk factors in urban areas of Ouagadougou, Burkina Faso. Malaria Journal. 2009;8: 13. pmid:19144144