Malaria Infection Study Thailand
The Malaria Infection Study in Thailand (MIST) is a program of research to accelerate development of vaccine and drugs for Plasmodium vivax. MIST is a collaboration between the Mahidol Vivax Research Unit (MVRU) and Mahidol Oxford Tropical Medicine Research Unit (MORU), funded by Wellcome, UK. The studies will involve carefully giving a controlled number of parasites to healthy volunteers and will be conducted at the Faculty of Tropical Medicine, which has a Clinical Research Centre, in dedicated, modern, well equipped facilities. The team has more than 50 years’ experience conducting world-class malaria research. The research will provide the platform for testing potential vaccines and drugs as well as other interventions for P. vivax.
Malaria diagnosis; At MVRU, we have been working on new ways to diagnose malaria. We were one of the first research groups to apply Loop Mediate Isothermal Amplification (LAMP) to detect malaria parasites. This technology works by amplifying the target DNA molecule at a single temperature, thus requiring simple instrumentation while maintaining very high detection sensitivity comparable to PCR. Our LAMP assays were created in response to the need of quick and easy diagnosis in the remote sites in Thailand. All types of human malaria parasites can now be detected and differentiated. These tools have helped us find low-density asymptomatic malaria carriers in our study areas.
Over the past decade, malaria incidence has steadily declined in various parts of the worlds. The resilience of P. vivax relative to P. falciparum against malaria controls can be attributed, at least partially, to the parasite’s ability to remain dormant as hypnozoites in the host’s liver. Primaquine is an effective drug to treat hypnozoite and has been included in the anti-malarial drug regimen in most of the countries. Primaquine, and other 8-aminoquinolone drugs, can induce severe hemolysis in malaria patients who deficient in glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. Female heterozygous G6PD deficiency is always missed by qualitative G6PD testing. Providing the primaquine to heterozygous G6PD malaria infected individual can potentially causing significant morbidity and diminish the impact of this drug. Studying G6PD deficiency especially in female heterozygous in the context of anti-malarial therapy and malaria elimination will support safe use of 8-aminoquinoline drugs for radical cure that will enable access to effective, life-saving therapy.
Malaria transmission; MVRU research on transmission of malaria is aimed to improve our understanding of how mobile human, populations, parasite drug resistance, and mosquito biology contribute to continuous malaria transmission at international borders so that innovative control strategies can be developed to support regional malaria elimination
Plasmodium vivax Biology
Biology; P. vivax has several unique biological features that are associated with its prevalence, clinical pathology, and transmission strategies. P. vivax selectively invades reticulocytes with the Duffy surface antigens. The kinetics of gametocyte production in P. vivax is also different with infective gametocytes appearing before the onset of the clinical symptoms. Most notably, P. vivax forms dormant hypnozoites in hepatocytes responsible for relapses of the disease, which poses a serious obstacle to the control and eventual eradication of this parasite. Our research at MVRU is aim to explore the molecular mechanism underlying those unique characteristics.
Drug & Vaccine Development
Drug and Vaccine development; MVRU and its partners have been a pioneer in discovering and testing new vaccines candidates for malaria transmission (TBVs), erythrocyte invasion, sporozoite invasion as well as testing new anti-malarial compounds against hypnozoites.
Malaria Epidemiology; MVRU has been conducting malaria mass blood and vector surveys in several hot-spot areas along the Thai-Myanmar border. Both cross-sectional and cohort study designs are used to precisely track malaria infections in human and their evolution over time. Mosquito captures are used to understand the seasonal dynamics of mosquito population as well as to identify the major malaria vectors in the study areas. These studies are also conducted in association with questionnaires developed to extract help identify groups of people who are under highest risk of malaria infection and to determine the effectiveness of interventions currently used in the country such as bednets and indoor residual sprays.Understanding the behavioral and demographic factors that underlie asymptomatic malaria infection will help policy makers identify individuals under high risks for proper intervention.