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Insecticide resistance monitoring : a review of current methology

Owusu, Henry F.. Insecticide resistance monitoring : a review of current methology. 2016, Doctoral Thesis, University of Basel, Faculty of Science.

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Official URL: http://edoc.unibas.ch/diss/DissB_12683

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Abstract

Introduction: Insecticide resistance continues to pose a serious threat to the control of vector-borne diseases. In the last decades, it has spread across Africa and many countries with high transmission of mosquito-borne diseases. A major handicap in the efforts to control resistance is the limited availability of routine and reliable data, a situation which arises from the fact that many countries with ongoing transmission of vector-borne diseases do not perform routine data collection, or in areas where data are available, there are high levels of inconsistencies in the reported data. Although WHO has put in place guidelines to be followed in performing bioassays to detect resistance, the guidelines are not standard operating procedure and leave room for discretion. Taking into account the importance of effective vector control and the limitation on the number of insecticide classes available, preserving the susceptibility of malaria vectors to the present classes of insecticides is essential in maintaining effective malaria control. The evolution of resistance to insecticides could endanger current and future achievements in controlling malaria. Therefore, the need for proper monitoring interventions equipped with well laid out guidelines cannot be overlooked.
Aims and objectives: The main aim was to review existing methodologies employed in insecticide resistance monitoring and identify factors that lead to inconsistencies in data generated in vector control strategies. This overarching aim is divided under three main objectives:
i. to assess the effect of bioassays on the test outcome;
ii. to assess the influence of the rearing conditions of mosquitoes on bioassay outcomes; and
iii. to assess the effect of inter laboratory variability on the outcome of the test.
Methods: Using laboratory-bred mosquito colonies, we performed susceptibility experiments with the principal diagnostic bioassays against insecticides mostly used in public health for the control of the major vectors involved in disease transmission to assess the robustness of the bioassays. We also bred mosquito larvae under different conditions to evaluate the effect of changes in environmental factors on the susceptibility of the adults to insecticides. The data generated was extended to a mathematical model to estimate the effects of larval population density on adult survival. The major sources of inter-laboratory differences in data generated in insecticide resistance monitoring activities were also tested by performing the WHO susceptibility assay at multiple centres.
Results: The results indicate that the WHO susceptibility and CDC bottle bioassays which are generally used interchangeably for both field and laboratory evaluations of insecticide resistance are highly inconsistent in generating the same results on the same mosquito population. The WHO cone assay also produces different results when the assay is performed at different angles. We also found the breeding conditions during the larval stage significantly affect the susceptibility status of the adult mosquito to insecticides. The mathematical models also showed that larval density significantly affects adult survival.
Conclusion: Results from this thesis reinforces the call for proper insecticide resistance monitoring tools and practices. While the problem of insecticide resistance is on the rise, the lack of effective and reliable methods to detect and monitor resistance remains a major concern.
Advisors:Tanner, Marcel and Müller, Pie and Gimnig, John
Faculties and Departments:05 Faculty of Science
03 Faculty of Medicine > Departement Public Health > Sozial- und Präventivmedizin > Malaria Vaccines (Tanner)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Epidemiology and Public Health (EPH) > Health Interventions > Malaria Vaccines (Tanner)
UniBasel Contributors:Tanner, Marcel and Müller, Pie
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:12683
Thesis status:Complete
Bibsysno:Link to catalogue
Number of Pages:1 Online-Ressource (xii, 135 Seiten)
Language:English
Identification Number:
Last Modified:12 Jul 2018 04:30
Deposited On:11 Jul 2018 11:15

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