Kerala is grappling with a surge in amoebic fever cases, also known as Primary Amoebic Meningoencephalitis (PAM), caused by the brain-eating amoeba Naegleria fowleri. The state has reported 69 confirmed cases and 19 deaths so far in 2025, nearly double last year’s tally of 36 cases and nine fatalities.

Health officials say infections are now being detected across multiple districts, unlike in earlier years when cases were linked to specific water sources. Recently, a 17-year-old student in Thiruvananthapuram contracted the disease after swimming in a public pool, prompting authorities to shut the facility and test its water quality. Several other patients remain in critical condition at hospitals.

Experts say the sharp rise in cases reflects multiple factors.

“Warmer temperatures have made freshwater bodies more hospitable to the amoeba, while poor sanitation in some wells and tanks has increased risks. Improved diagnostic capacity has also led to more cases being identified than in the past,” says Dr K K Vijyan, leading internist in Kerala.

A major global study published in The Lancet Infectious Diseases confirms that PAM is deadly in about 98 percent of cases. According to this report, Karachi, a major coastal city in Pakistan, is emerging as a hotspot for this infection. The first case of PAM in Karachi was reported in 2008, and by October 2019, there had been 146 cases. In just a decade, Pakistan recorded more cases than the US did in half a century, where 142 cases were reported between 1968 and 2019.

While most PAM cases in the US occur in children under 14, in Pakistan the majority are adults aged 26–45. This difference suggests that the strain in Pakistan may be genetically unique. Most infections in Pakistan happen during summer and before the monsoon season, and scientists are examining how climate change—longer, hotter summers and higher humidity—may be helping amoebas thrive in water, the study found.

There are 20 known species of Naegleria, but only N. fowleri infects humans. Its disease-causing mechanisms are not fully understood, which makes the infection so severe and rapidly fatal. Studying the amoeba’s genetic makeup could reveal why it is so deadly. Scientists are particularly interested in identifying unique genetic markers, new genes, and genes obtained from horizontal gene transfer. Whole-genome studies of the Pakistani strain could uncover these differences and help improve diagnosis and prevention.

Finally, there is an urgent need to educate the public on using boiled or properly treated water for nose rinsing to reduce the risk of infection, suggests the Lancet study.