Early diagnosis of primary amebic meningoencephalitis key to treatment




A 2014 Florida case of primary amebic meningoencephalitis (PAM) – a rare, typically fatal infection of the brain – is a reminder to physicians of the need for early diagnosis and prompt treatment of patients with suspected ameba infections.

PAM is a devastating infection caused by Naegleria fowleri, a free-living ameba found in warm, fresh water bodies throughout the world. Amebae like N. fowleri are aspirated into the nasal cavity through swimming, splashing, or nasal irrigation, and after attaching to the nasal mucosa, migrate across the cribriform plate to the brain via the olfactory nerves, causing extensive damage to the frontal lobes of the brain. In fact, only three nonfatal cases have ever been documented in the United States, according to a report in the Nov. 6, 2015, edition of the Morbidity and Mortality Weekly Report (MMWR. 2015 Nov 6;64[43]:1226).


In August 2013, miltefosine, an antiparasitic drug with activity against N. fowleri, became available from the Centers for Disease Control and Prevention as an investigational drug for the treatment of free-living ameba infections in combination with other antimicrobial drugs. Miltefosine was administered as part of the successful treatment of a case of PAM in 2013, and it can be requested from the CDC upon clinical suspicion of PAM infection and before laboratory confirmation.

Peggy J. Booth of the Florida Department of Health and coauthors related the case of an 11-year-old Florida boy hospitalized with a presumptive diagnosis of viral meningitis in June 2014. The initial cerebral spinal fluid (CSF) analysis was negative for motile ameba, but 2 days later – after the boy’s condition deteriorated – a second CSF specimen revealed the presence of motile ameba. Physicians consulted with the CDC and arranged for delivery of miltefosine, but the patient died before its arrival.

Ms. Booth and coauthors recommend that physicians consider a diagnosis of PAM in persons with a clinically compatible illness who have a history of fresh water exposure 1-9 days before illness onset. Early diagnosis and prompt treatment are essential because of the high mortality rate. The CDC is currently considering strategic placement of miltefosine in Texas and Florida, where approximately half of all cases in the United States have been reported, which might reduce the time to initiating treatment associated with transport of the medication.

To read the complete report in MMWR, click here.

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