Most cases of amoebic meningoencephalitis have been reported from individuals entering water bodies that were clearly not chlorinated. (Photo credit: The Hindu) | Photo credit: The Hindu
Even as public concern is growing over the rise in reported cases of amoebic meningoencephalitis and the “unknown” mode of transmission of the disease in many cases in Kerala, experts have clarified that the risk factors or general DOS associated with this infection and it is not something that has not already been released to the public.
Experts from the Kozhikode and Thiruvananthapuram Government Medical College Hospitals say the infection is being reported from many districts and that microbiologists seem to be just having a “diagnostic bias” picking up more cases in northern districts.
“Much ado is being made about a few cases of amoebic meningoencephalitis in which the epidemiological link is unclear. That does not mean that the entire public is universally facing a huge public health risk. For the majority of cases we had identified, there were clear risks which pre-disposed people to the infection—many patients had underlying diseases which made them immunocompromised; some had a history of entering waterbodies which were clearly not chlorinated, previous head injuries (which could have compromised their cribriform plate), and in some cases they had a seriously risky habit of nasal irrigation either as part of their religious practice or as part of ‘cleansing’ and the water was not clean enough,” says VK Shameer, assistant professor of general medicine, Kapozhodedmode College.
For RCC patients
Health officials confirm that some of the amoebic meningoencephalitis cases reported this year have been in immunocompromised cancer patients receiving treatment at a regional cancer center.
“There’s a lot we still don’t know, and we’re discovering a lot of information that might be new to the rest of the world. But the biggest risk factor for a healthy person to contract amoebic meningoencephalitis is continuing to dive into pools/streams or put tap water in their noses,” he says.
Medical literature states that Acanthamoeba is a ubiquitous organism that is present everywhere in the environment, even in seawater and Antarctica, and that it has been detected in tap water distribution systems and even in treated water from drinking water treatment plants in the US, indicating that some treatment processes may not completely eliminate this amoeba.
“This is a free-living amoeba, but it is also an opportunistic pathogen. It usually does not affect healthy individuals, but immunocompromised individuals are at risk of developing granulomatous amebic encephalitis if they have skin wounds through which Acanthamoeba can enter and spread to the brain via the blood,” says R. Aravind, infectious diseases director, Government College Hospitals, located in
High antibody prevalence
The literature also states that environmental exposure to both Naegleria and Acanthamoeba is so common that high antibody prevalence has been detected even in healthy individuals without active disease, making serology unreliable for detecting individual infections.
“Acanthamoeba colonization of the nasal cavity, without its invasion into the brain (the cribriform plate prevents this) or causing active infection in healthy individuals, has been clearly documented,” says Dr. Aravind.
Active amoebic infection is detected when an expert microbiologist sees motile amoeba in cerebrospinal fluid samples under direct microscopy. This is sufficient for clinicians to initiate empirical treatment (without waiting for confirmatory PCR), as early diagnosis is what saves lives.
“From 2024, clinicians in the country are ready to take on amoebic meningoencephalitis if the patient’s history reveals a link to any waterborne pathogen. In the case of Acanthamoeba, the incubation period could be weeks to months, and hence the patient’s history may not provide any information, a challenge that clinicians face every day,” says Dr. Aravind.
70 cases this year
Kerala had detected 39 cases of amoebic meningoencephalitis last year and nearly 70 cases have been reported this year.
Public health experts say the epidemiological data collected by the Health Department in all of these cases remains off-limits to researchers and public health experts, preventing any open scientific discussion about a disease that is of great public concern. “This data that has been hoarded is not doing the public health of the country any good. We need all the epidemiologists and experts on board so that we can study all aspects of this disease,” the public health expert says.
Published – September 15, 2025 05:18 PM IST
