At least 19 people have died of a rare infection caused by a “brain-eating” amoeba in India's southern state of Kerala, raising concern over the spread of the disease through freshwater bodies.
Kerala reported 70 cases of amoebic meningoencephalitis and 19 deaths, out of which nine patients died in September, according to the state's health department.
A three-month-old child, a nine-year-old girl, a 12-year-old boy and a 52-year-old woman were among the patients to have died of the infection while receiving treatment at a health facility in Kozihkode since mid-August.
Primary amoebic meningoencephalitis (PAM) is caused by Naegleria fowleri, a free-living organism commonly known as the “brain-eating amoeba”, which is found in warm freshwater such as lakes, ponds, rivers, and contaminated soil.
It enters the body through the nasal cavity and destroys brain tissue. Symptoms appear within days and lead quickly to seizures, coma and death. Although uncommon, the condition carries a high mortality risk, according to reports.
The initial symptoms of the disease are severe headache, fever, nausea and vomiting, which quickly escalate to stiff neck, sensitivity to light, loss of balance, seizures and eventually coma and death.
The state administration has launched a statewide chlorination drive covering fresh water lakes, tanks, well, and ponds. The state has introduced special treatment protocols and operating procedures for suspected cases.
Authorities in some parts of the state have placed signboards around ponds warning against bathing or swimming.
A Kerala health official told the New Indian Express that most of the victims had "some kind of comorbidity", which made them most vulnerable to the disease. "Amoeba is omnipresent. It attacks when we are weak," the official was quoted as saying.
The patients who died of the infection were also battling conditions such as tuberculosis, HIV, cancer, kidney disease, diabetes and hypertension, the Indian daily reported.
Health minister Veena George told the state assembly this week that higher detection led to more cases being classified as PAM instead of encephalitis, the general term for inflammation of the brain.
"This is not an epidemic. What is wrong in detecting the PAM cases that would have been otherwise reported as encephalitis? Early diagnosis is very important in saving lives," Ms George said.
She added: "The Kerala government had taken preventive steps. All districts have microbiology lab facilities for testing for PAM.”
Globally, amoebic meningoencephalitis shows a fatality rate of almost 97 per cent. In the US, there were 167 reported cases of PAM between 1962 and 2024. Only four have survived, according to the US Centre for Disease Control and Prevention.
India reported its first case in 1971, but infections remained rare until Kerala witnessed a sharp rise in recent years. The coastal state recorded only eight cases from 2016 to 2022, but confirmed 36 infections and nine deaths in 2023.
Kerala reported its first death of PAM infection in 2024 in a five-year-old girl.
Every known case in India until last year had been fatal. In July 2024, a 14-year-old boy from Kozhikode became the first patient in the South Asian country to survive the infection, joining just 10 other known survivors worldwide.
"Cases are rising but deaths are falling. Aggressive testing and early diagnosis have improved survival - a strategy unique to Kerala," Aravind Reghukumar, head of infectious diseases at the Medical College and Hospital in Thiruvananthapuram, told the BBC.
TS Anish, nodal officer at the Kerala One Health Centre for Nipah Research and Resilience in Kozhikode, says climate change is a major factor behind the recent rise in amoebic encephalitis cases in Kerala.
"Because of the rise in atmospheric temperature, microorganisms such as amoeba Naegleria fowleri that thrive in high-temperature environments have got prominence in the environment in the past decade or so," he told The Hindu.
"Species such as Naegleria fowleri mainly feed on bacteria and algae. The contamination caused by coliform bacteria, commonly found in faecal matter, is high in our water sources such as wells, ponds, and rivers," he added.
