Arbovirus burden and Aedes aegypti insecticide resistance in Colombia

Student thesis: Doctoral Thesis

Abstract

Aedes aegypti is the principal vector of dengue, Zika and chikungunya, viruses amongst the most significant public health concerns globally. The unavailability of vaccines and specific antiviral treatments for Aedes borne viruses (ABV) means that their management relies on controlling the vector mosquito, Ae. aegypti, most commonly with the use of insecticides. The reliance on insecticides for public health control programmes over many decades has led to widespread development of insecticide resistance in Ae. aegypti. This study investigated incidence of ABV and Ae. aegypti insecticide resistance in Colombia, one of the most heavily burdened countries, using a multifactorial approach. Socioeconomic and climatic factors driving ABV incidence in three distinct Colombian regions; Bello, Cúcuta and Moniquirá were investigated. The results identify differences in burden of ABV between the three Colombian regions and significant relationships between climate and socioeconomic factors and disease burden were also identified. Temephos susceptibility was profiled in Ae. aegypti larvae from the areas with lowest (Bello) and highest disease burden (Cúcuta) and differential gene expression (DGE) associated with temephos resistance was characterised using RNA-seq. Cuticle biosynthesis, ion exchange homeostasis, an extensive number of long non-coding RNAs, and chromatin modelling were among the differentially expressed genes in resistant Ae. aegypti larvae. The RNA-seq results also highlighted the importance of using a field relevant susceptible comparator strain when investigating resistance associated changes by identifying over estimation in DGE when resistant mosquitoes of field origin are compared only with susceptible lab populations. This study also trialled the novel use of Rapid Evaporative Ionisation Mass Spectrometry (REIMS) as a potential tool for rapid phenotyping of insecticide resistance in mosquitoes. Classification models built using the REIMS mass spectra were able to distinguish between temephos resistant and susceptible larvae with high accuracy, therefore identifying REIMS as a phenotyping tool with potential to complement existing strategies. Together these findings highlight the importance of using multifactorial approaches to increase understanding on the incidence of ABV and insecticide resistance in Ae. aegypti.
Date of Award6 May 2022
Original languageEnglish
Awarding Institution
  • Edge Hill University
SupervisorCLARE STRODE (Director of Studies) & JAYNE CHARNOCK (Supervisor)

Keywords

  • Aedes aegypti
  • Insecticide Resistance
  • Mosquitoes
  • RNAseq
  • REIMS
  • Dengue
  • Zika
  • Chikungunya

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