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Free-living amoebic encephalitis - Case series
Sithara Nasar Thottathil Puthanpurayil1, Aiswarya Mukundan1, Suryakala Ravi Nair1
1Department of Microbiology, Government Medical College, Thrissur, Kerala, India.
Introduction:
Free-living amoeba is ubiquitous in fresh water, mud, and moist soil; although seldom pathogenic to humans, Naegleria fowleri, Acanthamoeba spp., and Balamuthia spp. are known to cause infections of the central nervous system.
Methods:
We report two interesting cases, both of which presented with a rapid-onset and fulminant course. The first case details a 36-year-old male with a history of surgically corrected nasal bone fracture 15 years back, who presented with acute onset of fever, headache and convulsions.
Results:
Direct smears of cerebrospinal fluid (CSF) revealed motile trophozoites resembling N. fowleri and were later confirmed by molecular diagnosis (polymerase chain reaction [PCR]). Subsequently, the source was identified as water used for religious purposes. Unfortunately, the patient succumbed to cardiac arrest. The second case is that of a 4-year-old boy from Palakkad district, Kerala, who presented with sudden onset of nasal discharge, fever, headache, vomiting, seizures and altered sensorium. His CSF smear examination showed motile trophozoites resembling Acanthamoeba spp. While undergoing treatment, he seized thrice before going into cardiac arrest. Despite extensive resuscitation measures, the child could not be revived and passed away. The postmortem CSF sample sent for molecular analysis confirmed infection by Acanthamoeba spp.
Conclusion:
Rapid progression and lack of definite treatment options make this a highly fatal condition. Although clinical presentations of both patients were indicative of pyogenic meningitis, parasitic infection was suspected when the CSF was found turbid with no bacteria, high protein, and low sugar. High index of suspicion helped us to get an early preliminary diagnosis from direct microscopy.
Insights
Free-living amoeba infections, including Naegleria fowleri and Acanthamoeba, rapidly caused fatal central nervous system disease in two patients. Early diagnosis via microscopy and PCR was crucial but treatment options remain limited.
Area of Science:
- Neurology
- Infectious Diseases
- Parasitology
Background:
- Free-living amoebae (FLAs) like Naegleria fowleri, Acanthamoeba, and Balamuthia are ubiquitous in freshwater and soil.
- While generally not pathogenic, these amoebae can cause severe, life-threatening central nervous system (CNS) infections in humans.
Purpose of the Study:
- To report two cases of fulminant CNS infections caused by free-living amoebae.
- To highlight the diagnostic challenges and rapid progression of these rare infections.
Main Methods:
- Case report detailing clinical presentation, diagnostic procedures, and outcomes.
- Cerebrospinal fluid (CSF) analysis including direct microscopy and molecular methods (polymerase chain reaction [PCR]).
Main Results:
- Two patients presented with rapid-onset CNS symptoms mimicking pyogenic meningitis.
- Microscopy revealed amoebic trophozoites in CSF, confirmed by PCR for Naegleria fowleri and Acanthamoeba spp.
- Both patients unfortunately succumbed to their infections despite medical intervention.
Conclusions:
- CNS infections by free-living amoebae are rapidly progressive and highly fatal.
- Clinical suspicion is key, especially when CSF shows atypical findings (turbid, no bacteria, high protein, low sugar).
- Early diagnosis through direct microscopy and molecular techniques is vital for potential management, though treatment options are limited.
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