CDC created the national Free-living Ameba (FLA) Laboratory in 1978, which has become a national and global leader for diagnostic expertise and clinical guidance. As a national resource for health departments and clinicians, CDC’s FLA laboratory diagnoses most Naegleria fowleri infections in the U.S. In 1989, CDC began formally tracking Naegleria fowleri infections as part of the national Waterborne Disease and Outbreak Surveillance System (WBDOSS) 1. The CDC WBDOSS surveillance system and FLA laboratory track and assist with infections caused by Naegleria fowleri, Balamuthia mandrillaris, Acanthamoeba, and Sappinia.
The CDC Naegleria fowleri program focuses on five main areas to better understand and combat this disease:
Providing 24/7 diagnostic expertise and clinical guidance to health professionals
Tracking, investigating, and reporting infections and disease outbreaks
Leading CDC health promotion and communication activities
Testing the efficacy of promising drugs against the ameba in the laboratory setting
Developing new methods for detection of Naegleria fowleri in clinical and environmental samples (for example, in water)
Progress Being Made in All Five Areas
1. Providing 24/7 diagnostic services, clinical guidance, and an investigational drug to health professionals.
Assisting health professionals in diagnosing most infections in the U.S. as well as giving international assistance 1-10.
Consulting with physicians across the world to provide clinical guidance on treatment of Naegleria fowleri infections 6,7,11-14.
Providing the promising investigational drug, miltefosine, to clinicians, which contributed to the first US survivors of infection in 35 years 15.
Created extensive informational packets for immediate use by treating physicians.
Demonstrated that Naegleria fowleri can also infect other animals such as cows 16 and tapirs 17.
Co-discovered the non-pathogenic species Naegleria dunnbackei while investigating PAM deaths 18.
2. Tracking, investigating, and reporting infections and disease outbreaks.
Collecting tracking data on PAM infections in the United States as part of WBDOSS since 1989 and summarized every 2 years in CDC MMWR Surveillance Summaries.
Developing standardized information collection and investigation tools for investigators.
Completed an extensive retrospective research effort in 2007 with the Council for State and Territorial Epidemiologists (CSTE) to identify every reported U.S. infection and abstract all known information on the infections. After verification by all affected states, this database has become the national Naegleria fowleri infection database for use in tracking all future infections 1,2.
Co-sponsored a CSTE Position Statement 3 that established standardized case definitions for Naegleria fowleri and other FLA infections to improve future reporting of infections.
Assessing the potential for climate-related changes to the geographical range of the organism and associated infections.
Investigating the who, what, where, and why of primary amebic meningoencephalitis (PAM) infections to better understand the occurrence of disease, sources of infection and risk factors to potentially develop prevention recommendations in the future 4-13, 2, 14.
3. Leading CDC health promotion and communication activities.
Write and manage all content and web development for CDC’s Naegleria fowleri website.
Answer all public and media inquiries regarding Naegleria fowleri infections.
Make presentations to and create educational materials for public health, laboratory, and medical professionals to educate them about the disease, diagnosis, treatment, and prevention efforts 1-8.
Visvesvara GS. Pathogenic and Opportunistic Amebae. Manual of Clinical Microbiology, 9th ed. Murray PR, Baron EJ, Jorgensen JH, Landry ML, Pfaller MA, editors. Washington DC: ASM Press. 2007. p. 2082-91.
4. Testing the efficacy of promising drugs against the ameba in the laboratory setting.
The FLA laboratory has tested numerous drugs 1 against the ameba in the laboratory including the investigational drug miltefosine. It is a breast cancer and anti-leishmania drug that has shown in vitro (in laboratory culture) and animal model ameba-killing activity against Naegleria fowleri2. Miltefosine has also been used successfully to treat infections with the free-living amebae Balamuthia and Acanthamoeba2.
5. Developing new methods for detection of Naegleria fowleri in clinical and environmental samples.
The FLA laboratory developed specific antibodies directed against Naegleria fowleri and used these to develop an indirect fluorescence antibody test (IFA). This test has become the “gold standard” for Naegleria fowleri testing. The technology has been transferred to laboratories around the world 1, 2.
The diagnostics laboratory in CDC’s Division of Parasitic Diseases and Malaria developed a CLIA-certified laboratory polymerase chain reaction (PCR) test for simultaneously detecting Naegleria, Balamuthia, and Acanthamoeba DNA in clinical specimens 3. This test is now considered the equivalent of the “gold standard” IFA test.
CDC’s Molecular Diagnostics laboratory in the Waterborne Disease Prevention Branch has developed new methods to better understand genetic variation in Naegleria fowleri isolates to better understand whether different isolates differ in the severity or course of illness they cause 4.
The FLA Laboratory is collaborating with an international group of researchers to obtain the complete genetic code for Naegleria fowleri. This information could yield information important for treatment and detection of the ameba. Comparing the sequence with other Naegleria species may give an understanding of why Naegleria fowleri infects humans while other Naegleria species do not.
CDC’s Environmental Microbiology Laboratory in the Waterborne Disease Prevention Branch has sampled lake water using traditional methods. It is now developing advanced methods for the detection of Naegleria in water samples from lakes and rivers 5,6. This will allow CDC and others to test and potentially quantitate Naegleria in natural waters. This should facilitate future research into the ecology of Naegleria to help us understand where and why Naegleria grows and potentially assist in predicting areas of increased risk for swimming. No such predictions can be made at this time with current detection technology.
