Melioidosis

Melioidosis
Melioidosis abscess on the abdomen
Specialty	Infectious diseases
Symptoms	None, fever, pneumonia, multiple abscesses[1]
Complications	Encephalomyelitis, septic shock, acute pyelonephritis, septic arthritis, osteomyelitis[1]
Usual onset	1–21 days after exposure[1]
Causes	Burkholderia pseudomallei spread by contact to soil or water[1]
Risk factors	Diabetes mellitus, thalassaemia, alcoholism, chronic kidney disease[1]
Diagnostic method	Growing the bacteria in culture mediums[1]
Differential diagnosis	Tuberculosis[2]
Prevention	Prevention from exposure to contaminated water, antibiotic prophylaxis[1]
Treatment	Ceftazidime, meropenem, trimethoprim/sulfamethoxazole[1]
Frequency	165,000 people per year[1]
Deaths	89,000 people per year[1]

Melioidosis is an infectious disease caused by a gram-negative bacterium called Burkholderia pseudomallei.^[1] Most people exposed to B. pseudomallei experience no symptoms; however, those who do experience symptoms have signs and symptoms that range from mild, such as fever and skin changes, to severe with pneumonia, abscesses, and septic shock that could cause death.^[1] Approximately 10% of people with melioidosis develop symptoms that last longer than two months, termed "chronic melioidosis".^[1]

Humans are infected with B. pseudomallei by contact with contaminated soil or water. The bacteria enter the body through wounds, inhalation, or ingestion. Person-to-person or animal-to-human transmission is extremely rare.^[1] The infection is constantly present in Southeast Asia particularly in northeast Thailand and northern Australia.^[1] In temperate countries such as Europe and the United States, melioidosis cases are usually imported from countries where melioidosis is endemic.^[3] The signs and symptoms of melioidosis resemble tuberculosis and misdiagnosis is common.^[2] Diagnosis is usually confirmed by the growth of B. pseudomallei from an infected person's blood or other bodily fluid such as pus, sputum, and urine.^[1] Those with melioidosis are treated first with an "intensive phase" course of intravenous antibiotics (most commonly ceftazidime) followed by a several-month treatment course of co-trimoxazole.^[1] In countries with an advanced healthcare system, approximately 10% of people with melioidosis die from the disease. In less developed countries, the death rate could reach 40%.^[1]

Efforts to prevent melioidosis include: wearing protective gear while handling contaminated water or soil, practising hand hygiene, drinking boiled water, and avoiding direct contact with soil, water, or heavy rain.^[1] There is little evidence in supporting the use of melioidosis prophylaxis in humans. The antibiotic co-trimoxazole is used as a preventative only for individuals at high risk for getting the disease after being exposed to the bacteria in laboratory settings.^[1] One study conducted in 2018 determined that the drug could be useful in preventing melioidosis in high-risk renal failure patients undergoing haemodialysis.^[4] There is no approved vaccine for melioidosis.^[1]

Approximately 165,000 people are infected by melioidosis per year, resulting in about 89,000 deaths, based on a mathematical model published in 2016.^[5] Diabetes is a major risk factor for melioidosis; over half of melioidosis cases are in people with diabetes.^[1] Increased rainfall and severe weather events such as thunderstorms are associated with an increased number of melioidosis cases in endemic areas.^[2]