Melioidosis is a serious infectious disease caused by a bacterium found in the environment. It is often underdiagnosed and primarily occurs in specific parts of the world. The illness can present with a wide array of symptoms, making it difficult to identify.
The Source and Spread of Melioidosis
Melioidosis is caused by a bacterium named Burkholderia pseudomallei. This bacterium thrives in the soil and freshwater of tropical and subtropical climates. Its resilience allows it to survive in nutrient-poor conditions, such as desert soil and even distilled water, for extended periods. The bacterium is particularly widespread in Southeast Asia and northern Australia, where it is considered endemic. Cases have also been identified in other regions, including the Pacific, the Americas, and the Middle East.
Human infection typically results from direct contact with contaminated soil or water, especially through cuts or abrasions on the skin. Heavy rainfall or severe weather events can bring the bacteria to the surface, increasing the risk of exposure.
In addition to skin contact, the bacterium can be transmitted through other routes. Inhaling dust or water droplets containing B. pseudomallei is another significant mode of infection. This can happen in dusty environments or during weather events that aerosolize soil particles. Ingesting contaminated water is also a possible, though less common, method of transmission. Person-to-person spread is exceptionally rare.
Recognizing the Signs of Infection
Melioidosis is often called “the great mimicker” because its symptoms can be mistaken for those of other common illnesses, such as tuberculosis or pneumonia. The signs of infection are highly variable and depend on where the bacteria establish themselves in the body. Symptoms appear one to four weeks after exposure, but in some instances, the infection can remain dormant for months or even years before causing illness.
A localized infection may be the first indication of the disease. This form usually appears at the site where the bacteria entered the body, often a break in the skin. The signs include pain, swelling, and the formation of a skin abscess or ulcer.
When the infection targets the lungs, it results in a pulmonary form of melioidosis. Symptoms include a persistent cough, chest pain, high fever, and headache. Given the commonality of these symptoms, a correct diagnosis can be delayed without specific laboratory testing.
The infection can also enter the bloodstream, a condition known as septicemia. This is a severe form of melioidosis that can trigger fever, headache, respiratory distress, and a dangerous drop in blood pressure known as septic shock. This can result in the formation of abscesses in various internal organs, such as the liver, spleen, kidneys, or prostate, causing a wide range of additional symptoms like muscle or joint pain and seizures.
Medical Diagnosis and Treatment Protocols
Diagnosing melioidosis can be a challenge for healthcare providers due to its nonspecific symptoms. A definitive diagnosis relies on laboratory testing to identify B. pseudomallei in clinical samples. These samples can be taken from various sources depending on the patient’s symptoms, including blood, urine, sputum, or pus from an abscess or skin lesion. The bacteria are grown in a culture medium in the lab, which allows for positive identification.
Once melioidosis is confirmed, treatment involves a rigorous and extended course of antibiotics. The standard protocol is divided into two distinct phases to ensure the complete eradication of the bacteria from the body.
The first stage is the intensive phase, which requires the administration of intravenous antibiotics. This initial treatment is typically given in a hospital setting and can last for several weeks. Following the intensive phase, the patient transitions to a long-term eradication phase. This second stage involves taking oral antibiotics for a period that can last from three to six months. Completing the entire course of medication as prescribed is necessary to prevent the infection from returning.
Vulnerable Groups and Prevention Strategies
Certain individuals are more susceptible to contracting melioidosis and developing a severe form of the disease. The most significant risk factor is having an underlying medical condition, particularly diabetes. Other conditions that increase risk include liver disease, chronic kidney disease, chronic lung diseases like cystic fibrosis, and a blood disorder called thalassemia.
Occupational or recreational activities that involve frequent contact with soil and surface water also elevate the risk of exposure. This includes professions like farming and construction, as well as military personnel deployed to endemic regions. For people living in or traveling to areas where B. pseudomallei is common, taking specific precautions can significantly reduce the chance of infection.
A primary prevention strategy is to avoid direct contact with soil and standing water, especially after heavy rains. When contact is unavoidable, such as during agricultural work or gardening, wearing protective gear like waterproof boots and gloves is recommended.
If a skin injury like a cut or scrape occurs, it is important to clean the wound thoroughly and immediately. Covering any skin abrasions with waterproof dressings helps protect them from contamination. Additionally, it is advisable to drink only water that is known to be safe and uncontaminated to prevent ingestion of the bacteria.