Treatment

Primary amebic meningoencephalitis (PAM) is treated with a combination of drugs, often including amphotericin B, azithromycin, fluconazole, rifampin, miltefosine, and dexamethasone. These drugs are used because they are thought to be effective against Naegleria fowleri and have been used to treat patients who survived. Miltefosine is the newest of these drugs and has been shown to kill free-living amebae, including Naegleria fowleri, in the laboratory^{1, 2, 3}. Miltefosine has also been used to successfully treat patients infected with Balamuthia⁴ and disseminated Acanthamoeba infection⁵.

Although most cases of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri infection in the United States have been fatal (153/157 in the United States)^{6, 7}, there have been five documented survivors in North America: one in the United States in 1978^{8, 9}, one in Mexico in 2003¹⁰, two additional survivors from the United States in 2013 ^{5, 6}, and one from the United States in 2016. It has been suggested that the original U.S. survivor’s strain of Naegleria fowleri was less virulent, which contributed to the patient’s recovery. In laboratory experiments, the original U.S. survivor’s strain did not cause damage to cells as rapidly as other strains, suggesting that it is less virulent than strains recovered from other fatal infections¹³.

After 35 years without a Naegleria survivor in the United States, during the summer of 2013, two children with Naegleria fowleri infection survived. The first, a 12-year-old girl, was diagnosed with PAM approximately 30 hours after becoming ill and was started on the recommended treatment of amphotericin B, fluconazole, rifampin, azithromycin, and dexamethasone within 36 hours. She also received the investigational drug miltefosine,^7-9 and her brain swelling was aggressively managed with treatments that included cooling the body below normal body temperature (therapeutic hypothermia). This patient made a full neurologic recovery and returned to school. Her recovery has been attributed to early diagnosis and treatment and novel therapeutics including miltefosine and hypothermia¹¹.

A second child, an 8-year-old male, is also considered a PAM survivor, although he has suffered what is likely to be permanent brain damage. He was also treated with amphotericin B, fluconazole, rifampin, azithromycin, miltefosine, and dexamethasone but was diagnosed and treated several days after his symptoms began. Cooling of the body below normal body temperature was not used¹².

In the summer of 2016, a 16-year-old boy was reported as the fourth U.S. PAM survivor. This patient was diagnosed within hours of presentation to the hospital and was treated with the same protocol used for the 12-year-old 2013 survivor. This patient also made a full neurologic recovery and returned to school.