Improved Method for the Detection and Quantification of Naegleria fowleri in Water and Sediment Using Immunomagnetic
Bonnie J Mull1, Jothikumar Narayanan, Vincent R Hill
1Division of Foodborne, Waterborne and Environmental Diseases, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, 1600 Clifton Road, NE, Mail Stop D-66, Atlanta, GA 30329-4018, USA.
Abstract:
Primary amebic meningoencephalitis (PAM) is a rare and typically fatal infection caused by the thermophilic free-living ameba, Naegleria fowleri. In 2010, the first confirmed case of PAM acquired in Minnesota highlighted the need for improved detection and quantification methods in order to study the changing ecology of N. fowleri and to evaluate potential risk factors for increased exposure. An immunomagnetic separation (IMS) procedure and real-time PCR TaqMan assay were developed to recover and quantify N. fowleri in water and sediment samples. When one liter of lake water was seeded with N. fowleri strain CDC:V212, the method had an average recovery of 46% and detection limit of 14 amebas per liter of water. The method was then applied to sediment and water samples with unknown N. fowleri concentrations, resulting in positive direct detections by real-time PCR in 3 out of 16 samples and confirmation of N. fowleri culture in 6 of 16 samples. This study has resulted in a new method for detection and quantification of N. fowleri in water and sediment that should be a useful tool to facilitate studies of the physical, chemical, and biological factors associated with the presence and dynamics of N. fowleri in environmental systems.
Insights
A new method using immunomagnetic separation and real-time PCR can detect and quantify Naegleria fowleri (N. fowleri) in water and sediment. This tool aids in studying the ecology and risk factors of this rare, fatal infection.
Area of Science:
- Environmental microbiology
- Infectious disease diagnostics
- Molecular biology
Background:
- Primary amebic meningoencephalitis (PAM) is a rare and fatal infection caused by Naegleria fowleri.
- The first confirmed PAM case in Minnesota in 2010 underscored the need for better N. fowleri detection methods.
- Understanding N. fowleri ecology and exposure risk factors requires improved quantification techniques.
Purpose of the Study:
- To develop and validate a method for detecting and quantifying Naegleria fowleri in environmental samples.
- To establish a tool for ecological studies and risk assessment of N. fowleri.
Main Methods:
- Development of an immunomagnetic separation (IMS) procedure combined with a real-time PCR TaqMan assay.
- Testing the method's recovery rate and detection limit using seeded lake water samples.
- Application of the developed method to environmental water and sediment samples.
Main Results:
- The IMS and real-time PCR method achieved an average recovery rate of 46% in seeded lake water.
- The detection limit was determined to be 14 amebas per liter of water.
- N. fowleri was detected in 3 out of 16 environmental samples by direct real-time PCR and cultured from 6 out of 16 samples.
Conclusions:
- A novel and effective method for N. fowleri detection and quantification in water and sediment has been established.
- This method will be valuable for studying the environmental factors influencing N. fowleri presence and dynamics.
- Improved detection capabilities can support public health efforts to mitigate PAM risks.
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