Brief overview
- What is melioidosis? Melioidosis is a bacterial disease that mainly occurs in tropical and subtropical regions. Doctors also refer to it as pseudo-soot or Whitmore’s disease. For Europeans, it is important as a travel and tropical disease.
- Symptoms: Depending on the course of the disease, the clinical picture ranges from complete absence of symptoms to life-threatening blood poisoning. The first signs are usually fever, infections of the skin with lump formation and/or lung problems.
- Causes: Infection with the bacterium Burkholderia pseudomallei
- Diagnostics: Detection of the pathogen (from skin wounds, mucous membranes, blood or urine), detection of antibodies in the blood, computer tomography or magnetic resonance imaging to detect abscesses in internal organs
- Treatment: Antibiotics for several weeks or months, surgical removal of abscesses
- Prevention: General hygiene measures, treatment of skin wounds, no vaccination possible
What is melioidosis?
The term pseudo-soot refers to the similarity to glanders, a disease of solipeds caused by the bacterium Burkholderia mallei.
Distribution and frequency
Melioidosis only occurs in exceptional cases in Europe. It is mostly travelers who become infected in tropical and subtropical regions and import the pathogen. The main areas of distribution are Southeast Asia (especially Thailand), Singapore and northern Australia. The bacterium has also been occasionally detected in India, China, Taiwan, North and South America.
In addition to humans, domestic and wild animals as well as rodents also contract melioidosis, which is why the disease is classified as a zoonosis. These are diseases that are transmitted from animals to humans (and vice versa).
What are the symptoms of melioidosis?
The symptoms that occur vary from person to person. The range of symptoms extends from complete asymptomatic to life-threatening blood poisoning.
Symptoms of acute melioidosis
Skin: If the pathogen penetrates the skin via small wounds, a localized, purulent skin infection occurs at this site within a few days, and a small skin lump also forms. The lymph nodes in the vicinity of the infection site enlarge. Those affected have a fever and feel ill. In some patients, the skin infection develops into the “generalized form”, which affects the entire body and may be life-threatening.
Signs of a lung infection are
- fever
- Productive cough with partly bloody sputum
- Rapid breathing
Generalized form: Generalized melioidosis is the most severe form of the disease. It develops from both the skin and lung forms. The bacteria enter the bloodstream and are distributed throughout the entire body. Doctors refer to this as blood poisoning or sepsis, which is often fatal in melioidosis patients despite treatment.
As a defense reaction of the body to the bacteria, abscesses form in the lungs, liver and spleen, in the urogenital tract, in fatty tissue and in the joints.
Symptoms of chronic melioidosis
Possible symptoms are
- fever
- night sweats
- weight loss
- aches and pains
Cause and risk factors
The cause of melioidosis is an infection with the bacterium “Burkholderia pseudomallei”. It occurs in risk areas in wet soil, mud, ponds and rice fields and is extremely resistant: The pathogen survives for months in damp places.
If the bacterium enters the body, it can cause serious damage. This is caused by toxins (exotoxins) and enzymes (necrotizing protease) produced by the bacterium itself. The latter are triggers for abscesses that can potentially form in all organs.
How does the infection occur?
Human-to-human transmission is possible, but has only been described in isolated cases. The same applies to infected animals: Domestic and wild animals as well as rodents are potential, but rare, carriers when in close contact with humans.
Risk factors
The main risk factor for melioidosis is travel to areas where the pathogen is widespread, especially Southeast Asia and northern Australia.
People who come into contact with the pathogen for professional reasons are also at particular risk. These include vets, slaughterhouse staff and laboratory employees.
What does the doctor do?
The diagnosis of melioidosis is often difficult, as the disease often only breaks out weeks, months or even years after a stay in a risk area.
Pathogen detection
Antibody detection
A further test is carried out to confirm the diagnosis: the doctor examines whether antibodies against the pathogen are found in the blood. These prove that an infection with Burkholderia pseudomallei has already taken place.
Further examinations
In order to detect abscesses inside the body, the doctor usually carries out further examinations. Computed tomography (CT) of the chest, abdomen and pelvis and magnetic resonance imaging (MRI) of the head are suitable for this.
How is melioidosis treated?
Medication
Antibiotics are the drugs of choice for the treatment of melioidosis: In the first two to eight weeks of treatment (initial therapy), the patient receives the active ingredients ceftazidime or meropenem via the vein. The doctor then prescribes antibiotics for a further three to six months, which the patient takes orally (e.g. as tablets). Suitable active substances are trimetoprim/sulfamethoxazole, doxycycline or amoxicillin/clavulanic acid. Doctors refer to this second phase of treatment as eradication therapy.
Despite treatment, the fever in melioidosis typically only disappears after an average of nine days!
Surgery
Course of the disease and prognosis
In most cases (90 percent) melioidosis is acute, in 10 percent of all cases it takes a chronic course.
Acute melioidosis is life-threatening. If the bacteria enter the bloodstream, it leads to blood poisoning (sepsis), which is fatal within 24 to 48 hours in up to 40 percent of cases if left untreated. People with pre-existing conditions such as diabetics, immunocompromised or chronically ill people are particularly at risk. With appropriate treatment with antibiotics, more than 90 percent of patients survive.
Prevention
The possibilities of preventing melioidosis are limited to general hygiene measures. There is no vaccination.
As the pathogen is widespread in water and soil, travelers in risk areas should pay attention to personal hygiene and hygienic food preparation. It is also important to carefully clean and disinfect skin wounds.
