Malaria Infection Study in Thailand

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Malaria Infection Study in Thailand

20th June,2019, Dr. Jetsumon Sattabongkot Prachumsri

(Malaria Infection Study in 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. https://mist.in.th

Key Information

Funded by:
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Epidemiology and Transmission of Residual Malaria in Thailand

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« Research Spotlight | Malaria Epidemiology

Epidemiology and Transmission of Residual Malaria in Thailand

22nd March, 2018, Assoc. Prof. Dr. Wang Nguitragool

The world is trying to eradicate Malaria. Countries in Asia pacific aims to eliminate malaria from the region by 2030. A key challenge to achieve this aim is the remaining large number of asymptomatic carriers, local endemic residents who are infected by malaria parasites but do not suffer acute malaria symptoms. Unaware of their silent infection, most people do not seek anti-malarial treatment and become the source of parasites that can be transmitted to others including naïve travellers. Understanding the behavioral and demographic factors that underlie asymptomatic malaria infection will help policy makers identify individuals under high risks for proper intervention.

Over the past several years, we have been conducting malaria mass blood and vector surveys in several hot-spot areas along the Thai-Myanmar border. Our field sites run from villages of northern Tak province to rubber plantations in southern Ranong province. 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.

We have found that the vast majority of all malaria infection in the endemic area is asymptomatic and that P. vivax has undoubtedly become the most common parasite in Thailand. Anopheles minimus and Anopheles maculatus are the main malaria vectors. The wealth of data that we have accumulated over the past decade have helped us determine the hot spots of malaria infections and identified people who are most likely the silent parasite carriers. Whereas ethnic differences exist across our study populations, the major risks factors identified are constant. Importantly, we found strong association between indoor residual spraying with a reduction of malaria infection. We thus fully support the continuation of this intervention in the national malaria program.

Publications:

Key Information

In collaboration with:
Liwang Cui, Professor, University of South Florida
Guiyun Yan, Professor, University of California Irvene
Ivo Mueller, Professor, Walter + Eliza Hall
Ingrid Felger, Professor, Swiss THP
Funded by:

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Transmission Blocking Vaccines for Vivax Malaria

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« Research Spotlight | Malaria Epidemiology

Transmission Blocking Vaccines for Vivax Malaria

28th February, 2018, Assoc. Prof. Dr. Wang Nguitragool

The MVRU team and its partners have been a pioneer in discovering and testing new candidates for malaria transmission blocking vaccines (TBVs). These vaccines aim to interrupt transmission of malaria parasites from an infected individual to mosquitoes. Utilizing laboratory reared An. dirus, a Southeast Asian vector of malaria, and malaria infected blood from volunteers, we have been evaluating TBV candidates since 1998 and participated in a clinical Phase I study for the most advanced candidate Pvs25. Together with Mahidol Oxford Research Unit (MORU), we are in the process of initiating the first Controlled Human Malaria Infection study for Plasmodium vivax in a malaria endemic country.

Our works have contributed to down selection of key candidates for P. vivax malaria TBV. Using mosquito membrane feeding assays (MFA), we have shown that several candidates (Pvs25, Pvs28, Pvs45/58, Pvs230, AnAPN1) can significantly reduce malaria infection of mosquito. In some cases, man-to-mosquito transmission of the parasite can be blocked completely. Our works have provided key vaccine efficacy data essential for advancing vaccine candidates to clinical trials.

Publications:

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Malaria Genomics and Transcriptomics

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Malaria Genomics and Transcriptomics

Research_are_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.

Characterization of Plasmodium vivax gametocyte and its association with mosquito infectivity

Topic of research

International Laboratory Installation and Collaborative Research on Neglected Tropical and Vector-borne Diseases.

Outcome

Characterization of gametocyte development will lead to the discovery of the gametocyte markers which relate to the transmission of the parasite to mosquito. These markers can be used to determine the level of contribution to transmission of reservoir populations as well as to support the development of transmission blocking vaccines/drugs.

Key Information

  • Key MVRU Researchers:
  • Project Status:

    Past

  • Funded by:
    • National institute of Allergy and infectious diseases
    • Korean national institute of health
  • In collaboration with:
    • Liwang Cui, Professor, University of South Florida
    • Takafumi Tsuboi, Professor, Proteo-Science Center, Ehime University
    • Tomoko Ishino, Associate Professor, Proteo-Science Center, Ehime University
    • Motomi Torii, Professor, Proteo-Science Center, Ehime University
    • Eizo Takashima , Associate Professor, Proteo-Science Center, Ehime University

The development of Invasion inhibition assay for vaccine screening of Plasmodium vivax

Topic of research

Basic research related to Tropical diseases.

Outcome

Established high throughput invasion assay for in vitro vaccine screening of Plasmodium vivax. The optimized invasion assay will increase accuracy, productivity, and throughput of the assay which will fasten the antimalarial drugs/vaccines discovery.

Publications:

Key Information

  • Key MVRU Researchers:
  • Project Status:

    Past

  • Funded by:
    • Bill & Melinda Gates Foundation
    • Mahidol university
    • Korean national institute of health

 
Elucidating the Mechanism of Reticulocyte-Specific Invasion by Plasmodium vivax
      

Topic of research

Better understanding of P. vivax biology

Outcome

This project aims to provide a better understanding of the molecular process underlying how P. vivax senses and selects young erythrocyte to invade.

Key Information

Development of Plasmodium vivax gametocyte and its association with mosquito infectivity
      

 

Topic of research

Support deep knowledge base research. Also promote and support new researchers to continue research and stepping into higher-level research work.

Outcome

The information on P. vivax gametocyte development will give a better understanding of gametocyte biology and their infectiveness to the mosquito, allowing future identification of novel candidates for transmission blocking vaccines/drugs.

Key Information

  • Key MVRU Researchers:
  • Project Status:

    On-going

  • Funded by:
    • TRF
  • In collaboration with:
    • Liwang Cui, Professor, University of South Florida

Transcriptomes and Proteomes of Plasmodium vivax

Topic of research

Exploratory/Developmental research

Outcome

This study depict a comprehensive view of gene expression of P. vivax blood stage. Such information will help unravel the mechanism of sexual development which may lead to the discovery of new antimalarial drugs and transmission-blocking vaccine targets. This information will definitely fuel malaria elimination.

Key Information

  • Key MVRU Researchers:
  • Project Status:

    On-going

  • Funded by:
    • National institute of Allergy and infectious diseases
  • In collaboration with:
    • Liwang Cui, Professor, University of South Florida
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Malaria Diagnosis

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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.