Molecular Characterization and Pathogen Loads Assessment of Cimex Spp. (Bedbugs) in Selected Counties of Kenya

Abstract

Bedbugs, voracious blood-feeding ectoparasites, are indeed a potentially significant health problem within resident communities in Kenya. However, there is paucity of available studies on epidemiological or clinical data about the causal relationship between human beings and bed bugs. This study was carried out across selected infested counties in Kenya. The aim of this study was to identify, characterize, and assess pathogen loads for sustainable management of bedbugs in Kenya. A field survey was conducted in nine counties of Kenya namely, Nairobi, Mombasa, Kisumu, Bomet, Baringo, Narok, Machakos, Makueni and Kiambu using a semi-structured questionnaire. Nine hundred respondents (100 per county) were interviewed while five individual bedbug samples were used for genomic DNA extraction. Maximum entropy distribution modeling (MaxEnt) was used to map and predict the potentially suitable habitat, while Vensim PLE 8.0.9 software was used to implement Cimex spp. system dynamics models and carry out simulations. Field survey results revealed the socio-demographic profile of the respondents (females = 49.8%; males = 50.2%; minimum age = 18 years; maximum age = 96; mean age = 38.15 year), perceptions and incidence in the communities (weird occurrence = 80%; most active at night = 97%; mild bites = 68.9%; severe bites = 28.8%; disinfected more than once = 89.8%; present in bedroom/mattresses = 34%; furniture = 28%; cracks/crevices =24%; clothes =14%) and bedbug management practices (use of both chemical and cultural practices = 79.3%; cultural only = 10.3%; chemical only = 9.2%; botanicals = 1.1%). Morphological examination, confirmed through MtCOI gene sequencing, revealed that the collected bedbugs belonged to the Cimex genus. Further, molecular identification revealed that the examined samples belonged to two different species: Cimex hemipterus (n = 24; 67.7%) and Cimex lectularius (n = 12; 33.3%). The jack-knife test demonstrated that land cover and Temperature Seasonality (bio_4) are the most important variables in determining the suitability of bedbug in Kenya while Precipitation of Driest Month (Bio_14) and Precipitation of Warmest Quarter (Bio_18) variables significantly contribute to determining its suitability in Africa. Insecticide resistance was confirmed through VGSC gene sequencing revealing 79 (28.5%) of the 277 screened samples had the resistance gene. The total gut microbiome library size was 675,130 with Wolbachia (68.42%), Klebsiella (4.90%) and Escherichia (3.31%) detected as the predominant microbes. Wolbachia was the most predominant microbe in both of the species: Cimex hemipterus (70.72%) and Cimex lectularius (62.67%). A wide range of pathogenic genera including Escherichia (3.31%), Salmonella (0.72%) and Yersinia (0.45%) were detected in bedbugs. The results demonstrate that the pest is a global community ordeal, therefore these key study findings form a critical basis for designing, monitoring and implementing imperative control strategies with an ultimate goal of curbing the wide spread of the pest. This study therefore recommends integrated pest management (IPM) strategy by combining different control methods should be a better intervention approach in control of bedbugs as it also limits dependence on pesticides and reduces risks for humans and the environment.