Anti-parasitic and anti-fungal drugs drove that improvement against a disease that has historically killed about 97% of infected patients.
Naegleria fowleri infects people when contaminated warm freshwater enters the nose, then travels to the brain and can rapidly cause confusion, seizures, coma and death.
Around 500 cases have been documented worldwide in roughly 60 years, but the amoeba thrives in water up to 46C, raising concern that warming conditions could expand its range.
CDC advice for warm freshwater swimming includes holding the nose or using a nose clip; the amoeba is not spread person-to-person, by swallowing water or through salt water.