Clinical Features of Balamuthia Infection

Key points

  • Symptoms of a Balamuthia infection can take anywhere from a few weeks to several months to appear.
  • Balamuthia can cause a rare but nearly always fatal brain infection called granulomatous amebic encephalitis (GAE).
Man rubbing the back of his neck.

Signs and symptoms


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Symptoms of GAE can appear mild at first but can progress over weeks or months.

Early symptoms can include:

  • Confusion or other changes in mental status
  • Fever
  • Stiff neck or headache
  • Nausea or vomiting
  • Seizures
  • Focal neurological deficits or difficulty walking
  • Impaired speech, vision, or hearing

Some patients with GAE may have a sinus infection or an ear infection (otitis media).

Some patients might also have lesions in their mouth, especially on their palate. These lesions are chronic, and their appearance may change over time. They often start as papulonodular, erythematous lesions and enlarge over a period of weeks to months. The lesions are typically painless but can ulcerate and cause tissue destruction.

Most patients with Balamuthia skin lesions develop GAE. However, most people with Balamuthia GAE do not have skin lesions.

Clinical assessment

Brain imaging is usually abnormal for people with GAE. A magnetic resonance imaging (MRI) might show lesions, even if computed tomography (CT) scans are normal.

Typical findings on brain imaging have included ring-enhancing lesions up to 3-4 cm in size, hydrocephalus, and edema. Some patients have only one lesion, while others have many. Lesions can occur in any part of the brain, including the cerebral hemispheres, cerebellum, brainstem, and thalamus. Over time, lesions can increase in both size and number.

The amount of time it takes to get sick from a Balamuthia infection is unknown since the exposure to the ameba is usually unknown.

People who have been infected with Balamuthia through organ transplantation have developed symptoms between 14 and 24 days after their transplant. This might be faster than symptoms develop in patients with stronger immune systems.