Melioidosis (Whitmore disease) Symptoms, Transmission, Diagnosis and Treatment Guidelines

What is Melioidosis?

Melioidosis is an infectious disease caused by a Gram-negative aerobic bacilli bacteria called Burkholderia pseudomallei which is found in the soil and surface water. Melioidosis has different names and is also called Pseudoglanders diseaseWhitmore’s diseaseNightcliff gardener’s diseaseMorphia injector’s septicaemia or Paddy-field disease. Melioidosis is a wide spectrum of disease and may occur in different forms with most cases being subclinical infections. Common symptoms of Melioidosis are chest pains, bone pains, joint pains and skin infections.

Melioidosis Types

  1. Acute or chronic Melioidosis
  2. Localized or disseminated Melioidosis

One clinical form of Melioidosis may progress to another and individual patients may be difficult to categorize. The most serious form is septicaemic melioidosis because it is often complicated by multiple metastatic abscesses that are frequently fatal. Mortality rate of Melioidosis can be as high as 90% in the septicaemic forms and mortality rate of 10% in uncomplicated types.

Melioidosis Epidemiology

Melioidosis is distributed widely in the tropical and subtropical regions of the world with majority of clinical cases of Melioidosis occurring in South East Asia. It is endemic in Australia, Vietnam and Thailand, Burma, Malaysia, Brunei and Singapore. The highest incidence of Melioidosis is in Northeast Thailand.

Melioidosis Mode of Transmission

Transmission of Melioidosis occurs through inhalation of Burkholderia pseudomallei or direct inoculation. More than half of all patients with melioidosis have one disease that predisposes them to getting infected and it is commonly found in people with diabetes mellitus. Incubation period is variable and ranges from 121 days in the acute type and may take several years in the chronic type of Melioidosis.

Melioidosis Risk Factors

  1. Liver diseases
  2. Alcohol abuse
  3. Thalassemia
  4. Diabetes mellitus
  5. Chronic Kidney disease (CKD)
  6. Chronic Lung diseases such as Chronic Obstructive Pulmonary Disease or (COPD), and bronchiectasis).

Melioidosis Symptoms and Signs

  1. Fever
  2. Headache
  3. Cough
  4. Weight loss
  5. Chest pains
  6. Bone pains
  7. Joint pains
  8. There may be skin infections
  9. Pleural effusion (rare)
  10. Large and swollen lymph nodes
  11. There may be presence of cavitations on X-ray

Melioidosis Pathogenesis

Melioidosis is an indistinct nodular disease that is often widely scattered but tends to affect the upper lobes of the lungs. The nodules coalesce and form cavitations in majority of cases. The chronic form of Melioidosis mimics Pulmonary Tuberculosis because the nodules often involve the upper lobes and frequently cavitate. Hilar adenopathy is uncommon and pleural effusion is rare. Occasionally, pulmonary cavitation appears suddenly after years of initial infection. Melioidosis should suspected in a patient when a parenchymal cavity appears in an apparently healthy patient who was in an endemic area some years earlier.

Melioidosis Diagnosis

  1. Diagnosis of Melioidosis is by microscopy and culture of sputum, abscess pus or blood
  2. X-ray may show cavitations with or without hilar adenopathy

Melioidosis Treatment Guidelines

Treatment of Melioidosis is in two phases (Intensive Phase and Eradicative phase). In the intensive phase, intravenous drugs are given to reduce organisms load while the eradicative phase is to prevent reoccurrence.

Burkholderia pseudomallei which is the causative agent of Melioidosis has extensive intrinsic antibiotic resistance but the most effective drug is Ceftazidime that is given intravenously for 2 to 4 weeks and is followed by several months of administration co-amoxiclav (Amoxicillin/clavulanic acid) to prevent relapses. Severe Melioidosis can be treated with chloramphenicol, doxycycline or sulfamethoxazole in the eradicative phase to prevent relapse.

List of drugs that can treat Melioidosis

  1. Ceftazidime
  2. Chloramphenicol
  3. Doxycycline
  4. Sulfamethoxazole