Melioidosis (Whitmore's Disease)

What is melioidosis? What causes melioidosis?

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.

Where does melioidosis occur?

Melioidosis is most frequently reported in Southeast Asia and Northern Australia. It also occurs in South Pacific, Africa, India, and the Middle East. 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).

What are symptoms of melioidosis?

Melioidosis symptoms most commonly stem from lung disease where the infection can form a cavity of pus (abscess). The effects can range from mild bronchitis to severe pneumonia. As a result, patients also may experience fever, headache, loss of appetite, cough, chest pain, and general muscle soreness.
The effects can also be localized to infection on the skin (cellulitis) with associated fever and muscle aches. It can spread from the skin through the blood to become a chronic form of melioidosis affecting the heart, brain, liver, kidneys, joints, and eyes.
Melioidosis can be spread from person to person as well.

How is melioidosis diagnosed?

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 can not exclude the illness if it is negative.

How is melioidosis treated?

The treatment of melioidosis involves antibiotics and depends on the location of the disease.
For patients with more mild illness, the CDC recommends antibiotics such as imipenem, penicillin, doxycycline, amoxicillin-clavulanic acid, ceftazidime, ticarcillin-clavulanic acid, ceftriaxone, and aztreonam. Patients who are more severely ill are given a combination of two of the above for up to 12 months.
With pulmonary involvement of melioidosis, if cultures remain positive for six months, surgical removal of the lung abscess with lobectomy is considered.

Can melioidosis be prevented?

In counties where melioidosis occurs, people with compromised immune systems (such as AIDS, cancer, those undergoing chemotherapy, etc.) should avoid contact with soil and contaminated water, especially in farm areas.

What is the prognosis for melioidosis?

Untreated, melioidosis is fatal. When treated with antibiotics, severe forms of the illness have a 50% chance of recovery, but overall the mortality rate is 40%.

Melioidosis At A Glance

• 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%.

References:

eMedicine

U.S. Centers for Disease Control and Prevention 

Medical Author:

John P. Cunha, DO, FACOEP

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

Source:Medicinenet.com.