Melioidosis
Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei, which primarily resides in soil and water, particularly in regions like Southeast Asia, Australia, and parts of Africa. The disease can appear asymptomatic but often presents as skin and lung infections. Infection occurs through exposure of broken skin to contaminated soil or water, inhaling contaminated particles, or consuming contaminated food or water. The incidence of melioidosis tends to rise during the rainy season, with individuals with diabetes and other immune-compromising conditions being at greater risk.
Symptoms can range from localized skin abscesses and fever to severe respiratory distress and sepsis, leading to a high mortality rate if untreated. Diagnosis typically involves culturing the bacteria from clinical samples, and imaging studies may be utilized to identify abscesses. Treatment consists of antibiotic therapy, which varies based on the severity of the infection. Preventive measures include avoiding contact with potentially contaminated environments and practicing good hygiene. Awareness of melioidosis is crucial, especially for those in endemic areas or traveling to such regions.
Melioidosis
Anatomy or system affected:Lungs, respiratory system, skin
Also known as: Nightcliff gardener disease, paddy-field disease, pseudoglanders, Whitmore disease
Definition
Melioidosis is an infectious disease of humans and animals. It is caused by the bacterium Burkholderia pseudomallei, a natural inhabitant of soil and water commonly found in Southeast Asia, Australia, India, China, and regions of Africa. The related bacterium Burkholderia mallei causes the disease glanders, mainly in animals. Although melioidosis may be asymptomatic, it commonly manifests as an infection of the skin and lungs. B. pseudomallei has been listed as a potential biological warfare agent.
Causes
B. pseudomallei is ubiquitous in the soil, stagnantwaters, and rice paddies of endemic areas of the world. Humans become infected by exposure of abraded skin to contaminated soil or water, by inhaling contaminated dust particles, or by ingestion of contaminated food or water. The incidence of melioidosis is higher during the rainy season. In nonendemic regions, such as the United States, rare cases of melioidosis are associated with travel to affected regions.
Risk Factors
Although healthy persons may develop melioidosis, the most important risk factor associated with this disease is diabetes mellitus. Other risk factors include immune deficiencies, kidney disease, chronic lung disease, the blood disorder thalassemia, occupational hazards such as rice paddy cultivation, and travel in endemic areas.
Symptoms
The clinical presentation of melioidosis varies. It can be either acute (short term) or chronic (a minimum two months’ duration). The incubation period usually ranges from two to five days but may last years. Symptoms of acute localized infection usually include skin abscesses, muscle aches, and fever. Cough and chest pain, suggestive of pulmonary infection, may also be present. Severe symptoms include blood infection (sepsis) with high fever, abdominal pain, severe headaches, and respiratory distress. This form of the disease has a high mortality rate. Chronic melioidosis involves multiple-organ infection and usually manifests as joint and muscle pain.
Screening and Diagnosis
A definitive diagnosis is made when the culture from any clinical specimen (blood, urine, sputum samples, aspirated pus, or throat swabs) has B. pseudomallei organisms. Chest radiography and a computed tomography (CT) scan may be used to diagnose pulmonary melioidosis and abscess formation in body organs, respectively. Because its symptoms can occur in many types of infection, melioidosis is often misdiagnosed. This contributes to its deadliness, as the mortality rate when untreated is considered to be 70 percent at minimum, and generally higher.
Treatment and Therapy
Treatment consists of antibiotic therapy. Mildly ill persons usually receive one or more oral antibiotics for a course of a minimum of thirty days. Moderately or severely ill persons receive antibiotics intravenously for about fourteen days, after which a maintenance treatment with oral antibiotics is recommended for a period of up to one year.
Prevention and Outcomes
To reduce exposure to B. pseudomallei organisms, people living in endemic areas and travelers to these regions should avoid contact with soil, mud, and water; avoid drinking untreated water; practice adequate food hygiene and personal hygiene; and disinfect skin after contact with any suspected contaminated source.
Bibliography
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"Melioidosis." Center for Food Security & Public Health, Iowa State University, Jan. 2016, www.cfsph.iastate.edu/Factsheets/pdfs/melioidosis.pdf. Accessed 25 Oct. 2017.
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