Data on Balamuthia Infection

For Everyone

At a glance

  • Balamuthia mandrillaris lives in water, soil, and dust and enters the body through through cuts or skin wounds or from being inhaled into the lungs or nostrils.
  • Balamuthia infections can cause rare but serious illnesses, including a brain disease that is nearly always fatal.
  • CDC data show most cases occur among young boys and older men.
Balamuthia amebas in a patient’s brain. Thin arrows point to the infectious form of the ameba.

Cases by state

The map shows the number of U.S. Balamuthia cases by state from 1974 to 2025, with the most cases diagnosed in California and Texas. If a patient's state of residence was unavailable, the data reflects the state where the patient received treatment. Of the 155 total cases, 130 correspond to a patient's state of residence while 25 correspond to the state where a patient received treatment.

Cases by year

A total of 155 U.S. Balamuthia cases were diagnosed from 1974 to 2025, with a range of 0 to 9 cases a year. Infections include granulomatous amebic encephalitis that affects the brain, cutaneous disease that affects the skin, and disseminated disease that affects multiple organs.

Cases by age group and sex

Most U.S. Balamuthia cases from 1974 to 2025 occurred among boys 4 years and younger, followed by men 60 to 64 years, then girls 4 years and younger. Age is unknown for 2 cases while sex is unknown for 1 case.

Cases by month of illness onset

The first symptoms of a Balamuthia infection can occur any time of the year, according to data for 120 U.S. cases from 1974 to 2025. The month of illness onset is unknown for 35 cases.

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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)