Naegleria fowleri, commonly known as the “brain-eating amoeba,” is making alarming headlines across Kerala. Once considered a rare pathogen, it is now responsible for 105 cases and 23 deaths[1] due to primary amoebic meningoencephalitis (PAM) in the state this year. Read on to learn more about this deadly amoeba.
What Is Naegleria fowleri?
Naegleria fowleri is a thermophilic free-living amoeba that causes a rare and fatal infection of the brain called primary amoebic meningoencephalitis.
Sources: Lakes, ponds, hot springs, and poorly chlorinated swimming pools.
Mode of transmission: Contaminated water enters the body through the nose, usually during activities like swimming or diving.
Note: Swallowing contaminated water does not cause PAM, and person-to-person transmission is not possible.
The Lifecycle
The life cycle of N. fowleri involves three stages:
1. Cysts- Environment-resistant, dormant form.
2. Trophozoites- infective form
3. Flagellates- motile form.
Route of infection: Trophozoites enter the body → through the nasal mucosa → migrate via the olfactory nerves (present inside your nose) → penetrate a bony part called cribriform plate → reach the brain → cause PAM.
Kerala’s warm and humid climate provides ideal conditions for Naegleria fowleri to thrive. Rising water temperatures, stagnant ponds, and poorly maintained freshwater sources — especially after monsoon rains — create an environment where this amoeba can multiply rapidly. These seasonal and environmental factors are believed to contribute to the recent surge in Kerala amoeba cases.
What Happens During a Naegleria Infection?
Primary amoebic meningoencephalitis is a fatal central nervous system infection caused by N. fowleri that results in severe inflammation and destruction of brain tissue.
The early symptoms include:- headache, fever, nausea, and vomiting; followed by late symptoms such as neck stiffness, confusion, lack of attention to people and surroundings, loss of balance, and hallucinations.
Most people with PAM die within 1 to 18 days after symptoms begin.
Diagnosing PAM
Detection of trophozoites:
1. Wet mount microscopy of cerebrospinal fluid (CSF).
2. Brain tissue biopsy, performed after the patient's death.
Antigen detection methods: Identification of N.fowleri from brain tissue samples and CSF.
Polymerase chain reaction (PCR) is considered the gold standard and the method of choice for confirming PAM.
Why Is PAM Often Misdiagnosed?
Due to its rarity, its less frequently suspected by clinicians.
The symptoms of PAM mimic those of bacterial or viral meningitis.
Diagnosis is often made postmortem, as patients deteriorate fast.
Confirmatory tests are available only in a few specialized laboratories.
Treatment
Treatment of N.fowleri infection usually involves a combination of multiple drugs, as no single medicine is fully effective on its own. These include:-
Amphotericin B
Miltefosine
Rifampin
Azithromycin,
Azoles (for example, fluconazole)
Nanotechnology – A newer treatment method that uses nanoparticles bound to certain compounds that have shown strong amoebicidal (amoeba-killing) activity. However, this method is still under research.
The Indian Scenario
The first case of PAM in India was reported in 1971[2]. Since then only two dozen cases were reported nationwide, until recently.
Kerala reported its first case in 2016[2], and since 2023, there has been a surge in PAM cases, making it a growing public health concern. To understand the reason behind this surge, MedBound Times connected with Dr. Shabana Razmin, Head of Laboratory Medicine and Chief Microbiologist at Meitra Hospital, Calicut, to share her insights on the matter.
"The rise in the incidence of Primary Amoebic Meningoencephalitis (PAM) in Kerala may be attributed to several factors, such as climatic changes — particularly rising temperatures — and the contamination of surface waters, which together create favorable conditions for the rapid proliferation of causative organisms such as Naegleria fowleri and Acanthamoeba. In addition, advancements in diagnostic technologies and increased clinical awareness have likely contributed to the growing number of reported cases, particularly from regions like Calicut and Trivandrum."
Dr. Shabana Razmin, Head of Laboratory Medicine and Chief Microbiologist at Meitra Hospital, Calicut, Kerala, India
Can You Survive a Brain-Eating Amoeba Infection?
PAM infections are almost always fatal, with a mortality rate of 95–99%. Despite ongoing medical efforts, very little progress has been made in finding a reliable cure.
However, survival cases have been reported- 4 out of 157 cases in the USA, Mexico, Spain, and India.
Survivors are treated with a combination of medicines to kill the amoeba, along with intensive care to reduce swelling and pressure in the brain. These include:
Draining excess CSF from the brain
Lowering body temperature (induced hypothermia) to protect brain tissue
Osmolar therapy : using mannitol or concentrated saline to draw out fluid and reduce pressure inside the skull.
While survival remains rare, these cases provide hope and highlight the importance of early diagnosis and aggressive care.
Seek immediate medical attention if you experience:
Sudden severe headache
High fever
Nausea or vomiting
Neck stiffness
Confusion or loss of balance — especially after recent swimming or diving in warm freshwater.
Early detection and treatment are crucial, as Naegleria fowleri infections progress rapidly and can be fatal within days. Prompt medical care can improve survival chances.
Avoid swimming or diving in warm, untreated freshwater — especially in stagnant lakes or ponds during summer.
Use only sterile or boiled water for nasal rinsing (for example, during sinus cleaning or religious practices like ablution).
Ensure proper chlorination of swimming pools and public water sources.
Train healthcare professionals to recognize and treat PAM early —consider it in cases of meningitis, recent freshwater exposure, and initiate prompt treatment with anti-amoebic drugs and supportive care.
Mathrubhumi English. “Kerala Reports Fresh Case of Amoebic Meningoencephalitis: 23 Deaths Recorded So Far.” Accessed October 23, 2025. https://english.mathrubhumi.com/news/kerala/kerala-reports-fresh-case-of-amoebic-meningoencephalitis-23-deaths-recorded-so-far-kl2201xq
NDTV Health. “Kerala Reports Surge in Deadly Brain-Eating Amoeba Cases: Water Safety Measures.” Accessed October 23, 2025. https://www.ndtv.com/health/kerala-reports-surge-in-deadly-brain-eating-amoeba-cases-water-safety-measures-9200760
Centers for Disease Control and Prevention. “Naegleria Fowleri – About the Ameba.” CDC.gov. Accessed October 23, 2025. https://www.cdc.gov/naegleria/about/index.html
Mayo Clinic. “Naegleria Infection (Primary Amebic Meningoencephalitis).” Updated 2024. https://www.mayoclinic.org/diseases-conditions/naegleria-infection
PubMed Central. “Environmental Factors and Naegleria fowleri Occurrence in Freshwater.” ACS Omega 2023. https://pubs.acs.org/doi/10.1021/acsomega.3c08844
Reviewed by Dr. Shikhar Dabas
Edited by M Subha Maheswari
