Endemic Areas and Risk Factors for Burkholderia pseudomallei Infection
Geographic Distribution
Burkholderia pseudomallei is endemic in Southeast Asia and northern Australia, with the highest incidence reported from northeast Thailand, northern Australia, Singapore, Malaysia, and Vietnam. 1, 2
- The organism is a soil-dwelling saprophyte found in soil and surface water in endemic regions 2, 3
- Increasing reports are occurring worldwide, with estimates of up to 165,000 cases and 89,000 deaths annually 2
- Cases are increasingly recognized in travelers returning from subtropical and tropical regions 1
- Strong genetic differentiation exists between Thai and Australian B. pseudomallei populations, with no shared sequence types between the two regions, indicating geographical isolation 4
- Incidence is directly associated with high levels of rainfall in endemic areas 2
Primary Risk Factors
Diabetes mellitus is the most significant risk factor for melioidosis, along with male sex, alcohol abuse, and immunosuppression. 2
Host-Related Risk Factors:
- Diabetes mellitus - the predominant risk factor 2
- Male sex - significantly increased risk 2
- Chronic renal disease - high-risk population 1
- Alcohol abuse - major predisposing factor 2
- Immunosuppression - increased susceptibility 2
- Cystic fibrosis - documented cases of chronic pulmonary melioidosis 3
Exposure-Related Risk Factors:
- Direct contact with soil in endemic regions, particularly through open skin wounds 1
- Contact with standing water in endemic areas 1
- Inhalation of contaminated soil or water particles 2
- Ingestion of contaminated material 2
- Direct inoculation through skin breaks 2
Critical Clinical Pitfalls
- Patients with open skin wounds, diabetes, or chronic renal disease should strictly avoid direct contact with soil and standing water when traveling to endemic regions 1
- Clinicians managing travelers returning from subtropics or tropics with severe pneumonia or septicemia must consider acute melioidosis as a differential diagnosis 1
- The organism has potential for use as a biological weapon, making it a tier 1 select agent 2
- Certain genotypes are overrepresented in disease isolates compared to environmental samples, indicating differential virulence potential 4