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Melioidosis

Queensland Health Guidelines for Public Health Units

Revision History

Version Date Changes
1.0 February 2010  Full revision of guideline. 

Infectious Agent

The agent is a bacterium, Burkholderia pseudomallei.

Notification Criteria

Laboratory Definitive Evidence

Isolation of Burkholderia pseudomallei from any site.

Notification Procedure

Pathology Laboratories

To notify on confirmation of diagnosis by usual means.

Reporting to NOCS

Report only laboratory confirmed cases.

Confirmed case: A confirmed case requires laboratory definitive evidence.

Objectives of surveillance

  1. To monitor the epidemiology of melioidosis in Queensland.
  2. To identify clusters so that appropriate public health action can be taken.

Public Health Significance and Occurrence

Burkholderia pseudomallei is found in the soil in endemic areas. Melioidosis is regarded as endemic to southeast Asia and tropical Australia between latitudes 20°S and 20°N, although the infection has, on occasion, been acquired elsewhere in Australia. Most cases notified in Queensland are from the north of the State, in particular from the northwest Gulf country, the Torres Strait islands and from Townsville and nearby environs.

Risk factors for melioidosis include poorly controlled diabetes, chronic renal failure, excessive alcohol consumption, chronic lung disease, advance age and impaired immunity; infection probably occurs when non-intact skin has direct contact with contaminated soil or surface water. The incidence may increase following periods of heavy rain and flooding. It is thought this may be a result of the organism rising up to the surface from the deeper soil layers where it persists during the dry season.

Clinical Features

Melioidosis is an uncommon bacterial infection which presents as pneumonia, with or without septicaemia and can be rapidly fatal. Other presentations include skin abscesses or ulcers, abscesses in the internal organs such as the prostate, spleen, kidney and liver, fulminant septicaemia with multi-organ abscesses and neurological illnesses such as brainstem encephalitis. Most people exposed to the organism do not develop clinical illness.

The disease may manifest as long as 25 years after exposure.

Reservoir

The organism is saprophytic and is found in certain soils and waters. Various animals including sheep, goats, horses, swine and rodents can become infected and transfer the agent to new environmental foci.

Mode of Transmission

Usually via direct contact with contaminated soil or water through overt or inapparent skin wounds. It is also thought that transmission can occur via aspiration or ingestion of contaminated water, or via inhalation of soil, dust or minute water droplets.

Incubation Period

Can be as short as 2 days. However, years may elapse between presumed exposure and appearance of clinical disease.

Period of Communicability

Person to person transmission is very rare; neonatal cases suggest perinatal transmission can occur.  Laboratory-acquired infections may rarely occur, especially if procedures produce aerosols.

Susceptibility and Resistance

Disease in humans is uncommon even among people in endemic areas who have close contact with soil or water containing the infectious agent. Approximately two-thirds of cases have a predisposing medical condition, which may facilitate disease or recrudescence in asymptomatic infected individuals.

Management

Cases

Investigation
In consultation with the attending medical practitioner, ascertain any possible source of infection, including recreational or occupational activities that may lead to potential exposure to contaminated soil or water.

Treatment
Rapid instigation of antibiotic treatment is important. Specialist advice should be sought about ongoing treatment. Long-term antibiotics are required. Treatment for an inadequate length of time leads to a high probability of relapse.

Restriction
Nil.

Counselling
The case should be advised of the nature of the infection and its mode of transmission.

Contacts

Contact Tracing
No.

Community Outbreaks/Epidemics

If there is any temporal and geographical clustering of cases, further steps may need to be taken urgently. These may include:

  • collecting appropriate soil and/or water samples for culture for B. pseudomallei
  • examining the genetic relationship of the ‘cluster’ isolates using molecular techniques
  • informing local medical practitioners, and (if feasible) local residents of the cluster and about precautionary measures that could be taken (see below)
  • preparing media briefings about the disease, the 'cluster', the investigation and the precautionary measures.

Preventive Measures in Endemic Areas

Health education

  • Avoid contact with soil or muddy water, particularly after heavy rains.
  • Wear footwear and use gloves for gardening or while working outdoors, especially for those with predisposing conditions.
  • Open wounds, lesions or burns should be protected from coming into contact with potentially contaminated soil or water through the use of waterproof dressings. If potential exposure occurs skin should be washed thoroughly.
  • For diabetics, foot care and preventing contamination of foot or other lesions is important.

Feedback

Report to notifying agency.

Summary

Prepare a summary report of the investigation for the Communicable Diseases Branch, Queensland Health, on request.

References

Cheng AC, Currie BJ. Melioidosis: epidemiology, pathophysiology and management. Clin Microbiol Rev 2005; 18: 383-416.

Heymann D (Ed). 2008. Control of Communicable Diseases Manual, 19th edition. American Public Health Association: Washington.


Last updated: 9 September 2010