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Melioidosis

Category: Illness or disabilities

Type

Involuntary

Introduction and description

Whitmore's disease or Melioidosis is an infectious disease caused by a Gram-negative bacterium, Burkholderia pseudomallei, found in soil and water.

Person-to-person transmission is exceedingly unusual; and patients with melioidosis should not be considered contagious, however, Lab workers should handle B. pseudomallei under BSL-3 isolation conditions, as laboratory-acquired melioidosis has been described.

It is of public health importance in endemic areas, particularly in northeast Thailand, Vietnam, and northern Australia. It exists in acute and chronic forms.

The reported cases are 'but the tip of the iceberg'. This pathogenic saprophyte is commonly found in wet soil and water. An accidental or occupational exposure (in field workers, farmers, gardeners or villagers) to B. pseudomallei contaminated soil or pooled water is the primary source of infection.

Melioidosis is rare in the UK and cases are invariably imported; 22 cases associated with travel were reported in the UK between 1997 and 2006.  A Medline search for case reports using the keyword ‘Melioidosis’ within the last 5 years returned 76 results. A case of melioidosis was reported in the Irish Medical Journal in 2012, and a case of a melioidosis neck abscess was reported in the Journal of Laryngology and Otology in 2010, both were associated with travel. There are multiple case reports from South America, Australia, Singapore, Thailand, Malaysia, India and China.

The name melioidosis is derived from the Greek melis (μηλις) meaning "a distemper of asses" with the suffixes -oid meaning "similar to" and -osis meaning "a condition", that is, a condition similar to glanders.

Symptoms

Incubation is generally acute and of an order of 1–21 days. Symptoms may include pain in chest, bones, or joints; 'lumbago'; neurological symptoms; fever; and cough.  Clinical presentation includes localised skin infection, pneumonia, meningoencephalitis or systemic sepsis.

Diagnosis is through culture of body fluids on Ashdown's medium and can be facilitated by its characteristic pattern of antibiotic resistance.

Melioidosis can present as a chronic suppurative infection mimicking tuberculosis and presenting months to years following exposure. The latter has acquired the synonym ‘Vietnamese TB’ or the ‘Vietnamese time-bomb’.

Cause

B. pseudomallei was previously classed as part of the genus Pseudomonas; until 1992, it was known as Pseudomonas pseudomallei. It is phylogenetically related closely to Burkholderia mallei which causes glanders, an infection primarily of horses, donkeys, and mules.  Melioidosis is a saprophytic Gram-negative organism.

It is endemic in Northern Australia, South East Asia, the Indian Subcontinent and southern China. The highest prevalence rates are recorded for northeast Thailand. Infection is primarily through exposure to infected soil and ground water and usually through skin inoculation. Cases in American helicopter pilots during the Vietnam War suggested some cases might occur through inhalation. Infection rates are typically higher during the rainy season.

Treatment

Recommended treatment for melioidosis is "with an initial 10–14 days of intravenous ceftazidime or meropenem, followed by eradication therapy with co-trimoxazole +/− doxycycline for 12–20 weeks."

 

References and further reading

1. Warner JM, Pelowa DB, Currie BJ, et al. Melioidosis in a rural community of Western Province, Papua New Guinea. Trans R Soc Trop Med Hyg 2007;2013:809–13 [PubMed]
2. Currie BJ, Fisher DA, Howard DM, et al. Endemic melioidosis in tropical northern Australia: a 10 year prospective study and review of the literature. Clin Infect Dis 2000;2013:981–6 [PubMed]
3. Blaney DD, Gee JE, Smith TL. CDC traveller's health chapter 3. Infectious diseases related to travel. http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/melioidosis.htm (accessed 12 Apr 2013).
4. Health Protection Agency General information on melioidosis. http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Melioidosis/GeneralInformation/melioGeneralInformationMelioidosis/ (accessed 12 Apr 2013).
5. Malnich H, Englender HA, Dance DAD, et al. A decade of experience of the United Kingdom's melioidosis diagnostic service. http://www.hpa.org.uk/webc/HPAwebfile/HPAweb_C/1203496926848 (accessed 12 Apr 2013).
6. Estes MD, Dow SW, Schweizer HP, et al. Present and future therapeutic strategies for melioidosis and glanders. Expert Rev Anti Infect Ther 2010;2013:325–38 [PMC free article] [PubMed]
7. Cafferkey A, Collins J, Kane D, et al. An Antipodean infection. Ir Med J 2012;2013:125. [PubMed]
8. Garas G, Ifeacho S, Millard R, et al. Melioidosis and the vacuum-assisted closure device: a rare cause of a discharging neck wound, and a new approach to management. J Laryngol Otol 2010;2013:1021–4
9.  Neurol India. 2018 Jul-Aug;66(4):1100-1105. doi: 10.4103/0028-3886.236976.  Melioidosis mimicking tuberculous vertebral osteitis: Case report and review of literature.  Pande A1, Nambi PS2, Pandian S3, Subramanian S4, Ghosh S1.

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