As concerns rise among the public regarding an increase in reported amoebic meningoencephalitis cases in Kerala, and the perceived “unknown” ways some infections are occurring, medical experts are stepping forward. They emphasize that the fundamental risk factors and existing public health guidelines (the dos and don’ts) for this infection remain the same.
Medical professionals from Government Medical College Hospitals in Kozhikode and Thiruvananthapuram note that while cases are appearing across various districts, the higher numbers reported in northern regions might simply reflect a ‘diagnostic bias’ – meaning microbiologists there are more attuned to identifying the infection.
Dr. V.K. Shameer, Assistant Professor of General Medicine at Kozhikode Government Medical College, observes that there’s considerable discussion around a small number of amoebic meningoencephalitis cases where the exact cause is initially unclear. However, he reassures that this doesn’t imply a widespread, universal public health threat. For most identified cases, clear predisposing risk factors were present: many patients had underlying health conditions leading to compromised immune systems; others had used unchlorinated water bodies; some had undergone prior neurosurgery that could have affected their cribriform plate; and in certain instances, individuals practiced nasal irrigation (for religious reasons or sinus clearing) with water that was not adequately clean.
A Focus on Immunocompromised Patients
Health officials have confirmed that some amoebic meningoencephalitis cases this year were found in cancer patients with weakened immune systems, who were receiving treatment at the Regional Cancer Centre.
Dr. Shameer acknowledges that there’s still much to learn about the disease, and new information is continuously being discovered that could be globally significant. However, he stresses that for otherwise healthy individuals, the primary risk of contracting amoebic meningoencephalitis remains swimming or diving in untreated water bodies, or introducing tap water into the nostrils.
Existing medical literature indicates that Acanthamoeba is an organism found almost everywhere, from seawater to the Antarctic. It has even been identified in tap water distribution systems and treated drinking water in places like the U.S., suggesting that current water treatment methods might not always completely remove this amoeba.
Dr. R. Aravind, Head of Infectious Diseases at Government Medical College Hospital, Thiruvananthapuram, explains that while Acanthamoeba is a free-living amoeba, it can act as an opportunistic pathogen. It rarely causes illness in healthy people, but those with compromised immune systems are susceptible to granulomatous amoebic encephalitis, especially if the amoeba enters through skin wounds and travels to the brain via the bloodstream.
Widespread Antibody Presence
Further research reveals that environmental exposure to both Naegleria and Acanthamoeba is so common that a high prevalence of antibodies has been found even in healthy individuals who show no signs of active disease. This widespread antibody presence means that serological tests (blood tests for antibodies) are not dependable for diagnosing individual infections.
Dr. Aravind clarifies that it’s well-documented for Acanthamoeba to colonize the nasal cavity of healthy individuals without causing active infection or invading the brain, as the cribriform plate typically offers protection.
Diagnosing an active amoebic infection usually involves an expert microbiologist identifying the moving amoeba directly in cerebrospinal fluid samples under a microscope. This visual confirmation is sufficient for doctors to begin empirical treatment immediately, even before confirmatory PCR tests are back, as early intervention is critical for patient survival.
Dr. Aravind notes that since 2024, clinicians in Kerala have been specifically trained to consider amoebic meningoencephalitis if a patient’s history indicates exposure to water bodies. However, a significant challenge arises with Acanthamoeba, where the incubation period can span weeks to months, often making it difficult to pinpoint the source of infection from patient history alone.
Rising Case Numbers: 70 Cases This Year
Last year, Kerala identified 39 cases of amoebic meningoencephalitis. This year, that number has nearly doubled, with close to 70 cases reported so far.
Public health experts express concern that the epidemiological data collected by the Health Department for these cases remains inaccessible to researchers and other public health specialists. This lack of access hinders open scientific discussion and thorough investigation into a disease that is causing considerable public anxiety. One expert remarked, ‘This data hoarding is detrimental to the State’s public health. We need all epidemiologists and experts involved to fully understand every facet of this disease.’