The 50-year-old male patient is a construction worker from Wuhan, Hubei. On August 3rd, 2022, he was administrated with oral antibiotics and antipyretic treatment at the fever clinic of the First People's Hospital/Union Medical College Jiangnan Hospital in Jiangxia District, Wuhan due to fever. However, his condition did not improve. The next day, the family discovered that the patient was mentally ill, restless, and talking nonsense, so the patient was transferred to the neurology department. The family reported that the patient swam in a lake near the construction site on July 29th, 2022. On August 3rd, he developed a fever with a maximum body temperature of 39.0 ℃, accompanied by pain in the neck and vomiting. Admission examination showed clear consciousness, mild delirium, unable to cooperate with the examination, positive bilateral Pap sign, stiffed neck with a gap of 4 fingers, and positive bilateral K sign. Blood routine examination shows that white blood cell count is 17.5 × 10⁹/L with 86.5% neutrophils and procalcitonin 0.16 ng/ml. Lumbar puncture cerebrospinal fluid examination on August 5th showed a normal cerebrospinal pressure (145 mmH₂O, 1 mmH₂O = 9.779 Pa), an increase in white blood cell count (4 265.00 × 10⁶/L), multinucleated cells were increased (88.00%), Pan's protein test was positive, the total protein increased (2 394.2 mg/L), glucose was decreased (0.15 mmol/L), chloride was normal (114.66 mmol/L), potassium wad decreased (2.75 mmol/L). The head CT scan showed lacunar infarction in the left basal ganglia area. The high-throughput genetic examination of pathogenic microorganisms in the cerebrospinal fluid revealed Naegleria fowleri, with a relative abundance of 98.76%. Based on the epidemiological history, clinical symptoms and laboratory examination results, the diagnosis of primary amoebic meningoencephalitis was made. Dehydration, intracranial pressure reduction, anti-infection, anti-epilepsy, and maintenance of water-electrolyte balance were administered with mannitol (125 ml/6 h), ceftriaxone sodium (2.0 g/12 h), amphotericin B (1 mg on August 6th, 2 mg on August 7th, 3 mg on August 8th, and 4 mg on August 9th) were administered. Although the patient managed to control the seizure after treatment, the condition worsened gradually and on August 9th, he developed a cerebral hernia and died.