The control and eventual elimination of malaria in Africa is seriously challenged by drug resistance, in particular resistance to new artemisinin-based combination therapy (ACT) regimens. Worrisome signs suggest that high level resistance to components of ACT is on the way to Africa, a scary prospect, since the bulk of serious falciparum malaria occurs on this continent. Improved characterization of the extent of resistance and mechanisms of resistance is of critical importance. We hypothesize that antimalarial drug resistance is increasing in Uganda, that the rise of resistance will be dampened and obscured by parasite fitness costs, but that continued drug pressure will allow emergence of resistant parasites that maintain adequate fitness to spread readily. Preemptive analysis of parasites will be critical to characterizing resistance mechanisms before the problem is widespread. To test our hypotheses we will monitor the drug sensitivities of malaria parasites isolated from Ugandan patients under varied levels of drug pressure; characterize the genetic profiles of these parasites; assess the fitness, virulence, and transmissibility costs of resistanc in both clinical and laboratory settings; and characterize high level resistance selected clinicall or in the laboratory. We believe that focused evaluations of fresh Ugandan isolates will best equip us to characterize the emergence of high level resistance in Africa, where the malaria problem is greatest, and where timely characterization of resistance mechanisms can be most valuable. Our studies will benefit from access to a wealth of clinical trials in Uganda, studying the treatment and chemoprevention of malaria, and providing fresh isolates for genetic and parasitological evaluation. They will also benefit from our established laboratories for the study of malaria parasites in Kampala and Tororo. We believe that, to well characterize resistance, it is essential to study fresh isolates that have not yet lost key determinants in culture. Our specifc aims will be: (1) to assess impacts of selective pressures for resistance of malaria parasites to ACTs used for the treatment and chemoprevention of malaria, (2) to characterize phenotypes associated with diminished drug sensitivity, and (3) to identify mediators of high level drug resistance. Our overall goal is to better characterize antimalarial drug resistance and resistance determinants before the problem becomes widespread in Africa, so that monitoring of these determinants can guide efforts to circumvent the spread of resistance.

Public Health Relevance

Malaria remains one of the biggest infectious disease problems in the world, and a major reason for the continued problem is resistance of malaria parasites to available drugs. Resistance appears to be increasing, in particular to components of new artemisinin-based combination regimens. The goals of this project will be to assess resistance to antimalarial drugs in Uganda, to characterize key features of drug resistant parasites, and to identify factors leading to high level drug resistance, all to offer tools to beter control the spread of drug resistance.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI075045-07
Application #
8967551
Study Section
Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
Program Officer
O'Neil, Michael T
Project Start
2007-07-01
Project End
2019-11-30
Budget Start
2015-12-01
Budget End
2016-11-30
Support Year
7
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94118
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Rasmussen, Stephanie A; Ceja, Frida G; Conrad, Melissa D et al. (2017) Changing Antimalarial Drug Sensitivities in Uganda. Antimicrob Agents Chemother 61:
Walakira, Andrew; Tukwasibwe, Stephen; Kiggundu, Moses et al. (2017) Marked variation in prevalence of malaria-protective human genetic polymorphisms across Uganda. Infect Genet Evol 55:281-287
Tukwasibwe, Stephen; Tumwebaze, Patrick; Conrad, Melissa et al. (2017) Drug resistance mediating Plasmodium falciparum polymorphisms and clinical presentations of parasitaemic children in Uganda. Malar J 16:125
Taylor, Aimee R; Flegg, Jennifer A; Holmes, Chris C et al. (2017) Artemether-Lumefantrine and Dihydroartemisinin-Piperaquine Exert Inverse Selective Pressure on Plasmodium Falciparum Drug Sensitivity-Associated Haplotypes in Uganda. Open Forum Infect Dis 4:ofw229
Tumwebaze, Patrick; Tukwasibwe, Stephen; Taylor, Aimee et al. (2017) Changing Antimalarial Drug Resistance Patterns Identified by Surveillance at Three Sites in Uganda. J Infect Dis 215:631-635
Conrad, Melissa D; Mota, Daniel; Musiime, Alex et al. (2017) Comparative Prevalence of Plasmodium falciparum Resistance-Associated Genetic Polymorphisms in Parasites Infecting Humans and Mosquitoes in Uganda. Am J Trop Med Hyg 97:1576-1580
Asua, Victor; Tukwasibwe, Stephen; Conrad, Melissa et al. (2017) Plasmodium Species Infecting Children Presenting with Malaria in Uganda. Am J Trop Med Hyg 97:753-757
Yeka, Adoke; Kigozi, Ruth; Conrad, Melissa D et al. (2016) Artesunate/Amodiaquine Versus Artemether/Lumefantrine for the Treatment of Uncomplicated Malaria in Uganda: A Randomized Trial. J Infect Dis 213:1134-42
Rosenthal, Philip J (2016) Artefenomel: a promising new antimalarial drug. Lancet Infect Dis 16:6-8

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