Published on Infectious Disease Special Edition website, on September 22, 2021
Whole genome sequencing at the CDC showed the bacterial strains that infected the patients—one each in Georgia, Kansas, Texas and Minnesota—closely match each other, suggesting there is a common source for these cases. Two of the four patients had no known risk factors for melioidosis, and both children and adults have been infected.
Caused by the bacterium Burkholderia pseudomallei, melioidosis, or Whitmore’s disease, can infect humans or animals.
It is predominantly a disease of tropical climates, especially in Southeast Asia and northern Australia, where it is widespread. The strains in these U.S. cases appear most closely related to strains found in Asia, particularly South Asia, even though none of the patients had traveled internationally.
B. pseudomallei is found in contaminated water and soil, and spread to humans and animals through direct contact with the contaminated source. Humans and animals are believed to acquire the infection by inhalation of contaminated dust or water droplets, ingestion of contaminated water, and ingestion of soil-contaminated food or other contact with contaminated soil, especially through skin abrasions.
The CDC has collected and tested more than 100 samples from products, soil and water in and around the patients’ homes. No samples have yet been positive for B. pseudomallei.
Currently, the CDC believes the most likely cause is an imported product (such as a food or drink, personal care or cleaning products, or medicine) or an ingredient in one of those types of products. The bacteria normally live in moist soil and water. However, in rare cases, the bacteria also have been found to contaminate wet or moist products in areas where B. pseudomallei is common.
Identifying a single source of infection may be difficult because:
- The patients are spread apart by geography and time when their illness began.
- Each could have been exposed to potentially hundreds of products before they became ill.
- Unlike the organisms that cause most foodborne outbreaks, the bacteria responsible for melioidosis can take two to three weeks to make someone sick. This expands the window of time that investigators need to explore and means people may be less likely to remember everything they were exposed to before becoming ill.
The CDC asked clinicians to watch for any acute bacterial infection that does not respond to normal antibiotics and consider melioidosis, regardless of whether the patient traveled outside the United States. The CDC also urged clinicians not to rule out melioidosis as a possible diagnosis in children and those who were previously healthy and without known risk factors for melioidosis.
Disseminated melioidosis presents with abscess formation in various organs of the body and may or may not be associated with sepsis. Organs involved typically include the liver, lungs, spleen and prostate; involvement of the joints, bones, viscera, lymph nodes, skin or brain also may occur. Disseminated infection may be seen in acute or chronic melioidosis. Signs and symptoms, in addition to fever, may include weight loss, stomach or chest pain, muscle or joint pain, and headache or seizures.
Melioidosis Signs and Symptoms
Melioidosis has a wide range of signs and symptoms that can be mistaken for other diseases, such as tuberculosis or more common forms of pneumonia.
Localized infection:
Localized pain or swelling
- Fever
- Ulceration
- Abscess
Pulmonary infection:
- Cough
- Chest pain
- High fever
- Headache
- Anorexia
Bloodstream infection:
- Fever
- Headache
- Respiratory distress
- Abdominal discomfort
- Joint pain
- Disorientation
- Disseminated infection:
- Fever
- Weight loss
- Stomach or chest pain
- Muscle or joint pain
- Headache
Central nervous system/brain infection
- Seizures
Although healthy people may get melioidosis, underlying medical conditions may increase the risk for disease. The major risk factors are diabetes, liver or kidney disease, chronic lung disease, cancer or another condition that weakens the immune system. Most children who get melioidosis do not have risk factors. People experiencing cough, chest pain, high fever, headache or unexplained weight loss should see their doctor.
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