Melioidosis (Whitmore's Disease)

• Melioidosis is an infectious disease caused by a bacterium, Burkholderia pseudomallei.
• Melioidosis infection commonly involves the lungs.
• Melioidosis is diagnosed with the help of blood, urine, sputum, or skin-lesion testing.
• Melioidosis is treated with antibiotics.
• The overall mortality rate is 40%.

Melioidosis, also called Whitmore's Disease, is an infectious disease caused by a bacterium called Burkholderia pseudomallei (previously known as Pseudomonas pseudomallei). The bacteria are found in contaminated water and soil and spread to humans and animals through direct contact with the contaminated source. The bacteria are also of some concern as a potential agent for biological warfare and biological terrorism.

Melioidosis is similar to glanders disease, which is passed to humans from infected domestic animals.

Risk factors for developing melioidosis infection include

• living in Southeast Asia and northern Australia,
• diabetes,
• alcohol abuse,
• chronic renal disease,
• chronic lung disease,
• liver disease,
• thalassemia,
• kava consumption,
• cancer or another immune-suppressing condition not related to HIV, and
• chronic lung disease (such as cystic fibrosis, chronic obstructive pulmonary disease or (COPD), and bronchiectasis).

Other possible risk factors that may contribute to infection with melioidosis include steroid and other immunosuppressive therapy, rheumatic heart disease, congestive heart failure, pulmonary hemosiderosis, chronic granulomatous disease, and tuberculosis.

There are several different types of melioidosis, each with its own signs and symptoms.

• Pulmonary infection: Melioidosis signs and symptoms most commonly stem from lung disease where the infection can form a cavity of pus (abscess). The effects of a pulmonary infection can range from mild bronchitis to severe pneumonia. As a result, patients also may experience fever, headache, loss of appetite (anorexia), cough, shortness of breath, chest pain, and general muscle soreness.
• Localized infection: The effects can also be localized to infection on the skin (cellulitis) with pain or swelling, ulceration, and abscess, with associated fever and muscle aches.
• Bloodstream infection: If melioidosis enters the bloodstream, symptoms can include fever, headache, respiratory distress, abdominal discomfort, joint pain, and disorientation.
• Disseminated infection: Melioidosis can spread from the skin through the blood to become a chronic form of melioidosis affecting the heart, brain, liver, kidneys, joints, and eyes. Symptoms of a disseminated melioidosis infection include fever, weight loss, stomach or chest pain, muscle or joint pain, headache, and seizures.

Melioidosis is minimally contagious. It can be spread from person to person, though it is rare. The most common route of infection with melioidosis is through direct contact with contaminated soil and water, especially though open wounds on the skin. Humans and animals can also acquire the infection by inhaling dust particles or water droplets or ingesting water that is contaminated.

Primary-care providers (PCPs), such as family practitioners, internists, pediatricians, and emergency-medicine specialists may initially treat patients, but individuals with severe complications may be treated by infectious-disease specialists or critical-care specialists.

The diagnosis of melioidosis is made with a microscopic evaluation of a blood, urine, sputum, or skin-lesion sample in the laboratory. A blood test is useful to detect early acute cases of melioidosis, but it cannot exclude the illness if it is negative.

The incubation period for melioidosis ranges from one to 21 days, with an average of nine days to onset of infection. Symptoms typically appear two to four weeks after exposure.

Melioidosis is most frequently reported in southeast Asia, northern Australia, south Asia (including India), and China. The majority of patients are from Thailand, Malaysia, Singapore, and northern Australia. Melioidosis has also been reported in Papua New Guinea and New Caledonia. The bacterium that causes the disease is found in the soil, rice paddies, and stagnant waters of the area. People acquire the disease by inhaling dust contaminated by the bacteria and when the contaminated soil comes in contact with abraded (scraped) area of the skin. Infection most commonly occurs during the rainy season.

In the United States, confirmed cases range from none to five each year and occur among travelers and immigrants, according to the U.S. Centers for Disease Control and Prevention (CDC).

The treatment of melioidosis involves antibiotics and depends on the location of the disease.

For patients with more mild illness, the CDC recommends medication with antibiotics such as imipenem, meropenem (Merrem), penicillin, doxycycline (Doryx, Oracea, Monodox), amoxicillin-clavulanic acid (Augmentin, Augmentin XR), ceftazidime (Fortaz, Tazicef), ticarcillin-clavulanic acid (Timentin), ceftriaxone (Rocephin), and aztreonam (Cayston, Azactam). Patients who are more severely ill are given a combination of two of the above medications for three to six months.

After the initial intensive therapy, eradication therapy may be initiated using trimethoprim-sulfamethoxazole (Bactrim, Sulfatrim).

With pulmonary involvement of melioidosis, if cultures remain positive for six months, surgical removal of the lung abscess with lobectomy is considered.

Prevention of infection in areas where melioidosis occurs includes minimizing risk of exposure to the bacteria.

• People with compromised immune systems (such as AIDS, cancer, those undergoing chemotherapy, etc.), open skin wounds, diabetes, or chronic renal disease should avoid contact with soil and contaminated water, especially in farm areas.
• People who work in agriculture should wear proper gear, including work boots, to prevent infection in the feet and legs.
• Health-care workers should use standard safety precautions, including masks, gloves, and gown to prevent infection.

Untreated, melioidosis is fatal. When treated with antibiotics, severe forms of the illness with sepsis and complications that arise from that condition have an overall mortality rate of approximately 40%.