Environment, Pathogens, and Host Interactions in Melioidosis (DeEPH)

Decoding the Triad: the Interplay Between Environment, Pathogen, and Host in Melioidosis (DeEPH)

This is a longitudinal, multicentre observational study conducted across three established microbiology units integrated within hospital and community health systems in Thailand, Lao PDR, and Cambodia.

The hospital cohort will enroll approximately1,000 patients with positive melioidosis. Participants will be followed at six time points from admission through one year (post-discharge) to capture acute and recovery-phase outcomes, with clinical data collected on demographics, comorbidities, exposures, treatment, adherence, and outcomes.

For each confirmed case, a healthy control will be recruited within two weeks and matched by age, sex, and village of residence. Controls with no symptoms or history of melioidosis will provide a single blood sample at enrolment and will be followed by telephone at 6 and 12 months.

In addition to hospital-based surveillance, a high-risk community in northern Ubon Ratchathani-referred to as the Sandbox Village-will be intensively monitored to capture subclinical infections and to assess environmental factors influencing disease acquisition.

This study is funded by the Wellcome Trust. The grant reference number is 323077/Z/24/Z

Study Overview

• Status: Not yet recruiting
• Conditions: Melioidosis

Detailed Description

This is a longitudinal, multicentre observational study conducted across three established microbiology units integrated within hospital and community health systems:

• Sunpasitthiprasong Hospital, Ubon Ratchathani, Thailand (MORU);
• Mahosot Hospital, Vientiane, Lao PDR (LOMWRU); and
• Angkor Hospital for Children, Siem Reap, Cambodia (COMRU).

In addition to hospital-based surveillance, a high-risk community in northern Ubon Ratchathani-referred to as the Sandbox Village-will be intensively monitored to capture subclinical infections and to assess environmental factors influencing disease acquisition.

Participant Recruitment and Follow-up

Hospital cohort:

Patients with melioidosis will be recruited at all three hospital sites. The study plans to recruit 1,000 patients, who will be followed longitudinally at six time points: Day 0 (admission), Days 3 and 7 (acute phase), and Days 30, 180, and 365 (recovery phase).

Clinical data collected will include demographic characteristics, underlying comorbidities, environmental exposures, lifestyle and behavioural factors, treatment history, patient-reported medication adherence, and follow-up outcomes.

Healthy controls:

Each patient will be matched with a healthy control recruited within two weeks of diagnosis, based on age, sex, and village of residence. Controls will have no current symptoms or prior history of melioidosis. They will provide a single blood sample at enrolment for DNA extraction and antibody profiling and will be followed up by telephone on Days 180 and 365.

Community cohort:

To complement hospital-based data and to identify subclinical infections, intensive community surveillance will be conducted in the Sandbox Village, a high-incidence area within the Ubon Ratchathani region. All residents (approximately 400 individuals) will be enrolled. DNA samples will be collected at baseline, and serum samples will be obtained every two months over a 42-month period, either at participants' homes or at a central village location, to measure antibody responses to Burkholderia pseudomallei as a proxy for exposure.

Community cohort:

To complement hospital-based data and to identify subclinical infections, intensive community surveillance will be conducted in the Sandbox Village, a high-incidence area within the Ubon Ratchathani region. All residents (approximately 400 individuals) will be enrolled. DNA samples will be collected at baseline, and serum samples will be obtained every two months over a 42-month period, either at participants' homes or at a central village location, to measure antibody responses to Burkholderia pseudomallei as a proxy for exposure.

• Study Type: Observational
• Enrollment (Estimated): 2400

Contacts and Locations

• Study Contact: Name: Kamolchanok Claire Chewapreecha, PhD; Phone Number: 662 203 6333; Email: claire@tropmedres.ac

Study Locations

• Cambodia
  • Siem Reap, Cambodia
    • Cambodia-Oxford Medical Research Unit (COMRU)
    • Contact: Paul Turner, MD; Email: Pault@tropmedres.ac
• Laos
  • Vientiane, Laos
    • Lao-Oxford-Mahosot Hospital Wellcome Trust Research Unit (LOMWRU)
    • Contact: Elizabeth Ashley, MD; Email: Elizabeth.Ashley@tropmedres.ac
• Thailand
  • Ubon Ratchathani, Thailand
    • Sunpasitthiprosong Hospital
    • Contact: Kamolchanok C Chewapreecha, PhD; Phone Number: 022036333; Email: claire@tropmedres.ac

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Melioidosis patients:

Patients confirmed to have melioidosis.

Healthy controls:

For each confirmed melioidosis case, a healthy control-defined as having no current fever, no evidence of soft tissue infection, and no prior history of melioidosis-will be recruited from satellite blood bank donors within approximately two weeks of case identification. Controls will be matched by age (±5 years), sex, and village of residence.

Sandbox Village residents:

All residents of the Sandbox Village, a high-risk area for melioidosis, will be enrolled to monitor disease progression and to evaluate the impact of improved water sanitation.

Description

Inclusion criteria for melioidosis patients:

• Age ≥20 years
• Positive for Burkholderia pseudomallei from any clinical samples
• Resident of the study area for at least two years, including the follow-up period
• Willing to participate and give informed consent.

Inclusion criteria for healthy controls:

• Age ≥20 years
• Currently healthy as judged by study doctor
• Resident of the study area for at least two years, including the follow-up period
• Willing to participate and give informed consent.

Inclusion criteria for sandbox residents:

• Age ≥20 years
• Resident of the study area for at least two years, including the follow-up period
• Willing to participate and give informed consent.

Exclusion criteria for melioidosis patients:

• Current tuberculosis (TB) or TB treatment within the past six months
• Documented HIV infection or use of immunosuppressive therapy in the past 12 months

Exclusion criteria for healthy controls:

• History of melioidosis
• Significant acute illness
• Current fever or soft tissue infection

Exclusion criteria for sandbox residents

-N/A

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort
Melioidosis patients; Patients confirmed to have melioidosis
Healthy controls; Healthy controls will be enrolled for each confirmed melioidosis case. A healthy control is defined as an individual with no current fever, no evidence of soft tissue infection, and no prior history of melioidosis. Controls will be recruited within approximately two weeks of case identification and will be matched to cases by age (±5 years), sex, and village of residence.
Sandbox village cohort; All residents of the Sandbox Village, a high-risk area for melioidosis, will be enrolled to monitor disease progression and to evaluate the impact of improved water sanitation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Development of melioidosis following exposure, assessed among melioidosis cases	365 days
Development of melioidosis following exposure, assessed among healthy controls	365 days
Development of melioidosis following exposure, assessed among Sandbox Village residents	3.5 years
Mortality during the acute phase of infection among individuals with melioidosis (melioidosis cases).	365 days
Number of hospital readmissions following discharge among individuals with melioidosis (melioidosis cases).	365 days

Secondary Outcome Measures

Outcome Measure	Time Frame
Changes in disease development following exposure associated with interactions between environmental modifications.	3.5 years
Changes in mortality during the acute phase of infection following exposure associated with interactions between environmental modifications.	365 days
Changes in hospital readmission following recovery associated with interactions between environmental modifications.	365 days
Changes in disease development following exposure associated with interactions between clinical management factors.	365 days
Changes in mortality during the acute phase of infection following exposure associated with interactions between clinical management factors.	365 days
Changes in hospital readmission following recovery associated with interactions between clinical management factors.	365 days
Changes in disease development following exposure associated with interactions involving genetic susceptibility.	365 days
Changes in mortality during the acute phase of infection following exposure associated with interactions involving genetic susceptibility.	365 days
Changes in hospital readmission following recovery associated with interactions involving genetic susceptibility.	365 days

Collaborators and Investigators

• Sponsor: University of Oxford
• Investigators: Principal Investigator: Kamolchanok Claire Chewapreecha, PhD, Mahidol Oxford Tropical Research Unit

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): December 1, 2034
• Study Completion (Estimated): December 1, 2034

Study Registration Dates

• First Submitted: January 7, 2026
• First Submitted That Met QC Criteria: January 7, 2026
• First Posted (Estimated): January 16, 2026

Study Record Updates

• Last Update Posted (Estimated): January 16, 2026
• Last Update Submitted That Met QC Criteria: January 7, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Infections; Bacterial Infections; Bacterial Infections and Mycoses; Gram-Negative Bacterial Infections; Burkholderia Infections; Melioidosis
• Other Study ID Numbers: MEL25001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

The study outputs, including genomic and transcriptomic data and associated metadata, will be valuable for future research. In compliance with the Wellcome Trust's open data policies and to encourage reproducibility, data will be deposited in two repositories:

Human genomic and transcriptomic data: European Genome-Phenome Archive (EGA), under managed access

Bacterial genomic data: European Nucleotide Archive (ENA), open access

Pseudonymised metadata, including participant demographics and microbiological findings, will be shared with qualified researchers in accordance with the General Data Protection Regulation (GDPR). No personally identifiable information will be shared, and participants will not be identifiable from any released data.

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No