This brain-eating amoeba is on the rise
This brain-eating amoeba is on the rise
Excerpt from this National Geographic story:
A 14-year-old boy who went swimming in a pond in India’s sweltering heat. A 13-year-old girl who bathed in a pool during a school excursion, and a five-year-old girl who took a dip in a river near her home. The three children lived in different parts of the southern Indian state of Kerala. Yet they have something in common ⸺all of them succumbed to a brain infection, Primary Amoebic Meningoencephalitis (PAM), caused by a tiny organism found in warm freshwaters and poorly maintained swimming pools. About a dozen others have been undergoing treatment in India, one of whom, a 27-year-old man, has also succumbed.
Although rare, PAM is a deadly infection with a worldwide occurrence. It is caused by Naegleria fowleri, also known as the “brain-eating amoeba”, as it infects the brain and destroys brain tissue. At least 39 countries have reported such infections so far, and the rate of infections is increasing by 4.5 percent every year. In Pakistan alone, 20 deaths are reported every year due to the disease, and in 2024, infections have been reported in India, Pakistan, and Israel. N. fowleri was also detected at a popular freshwater swimming spot in Western Australia and hot springs in the U.S’s Grand Teton National Park.
According to the Centers for Disease Control and Prevention (CDC), the majority of global case exposures⸺85 percent⸺have been reported during warm, hot, or summer seasons. Several studies have also observed that changes in temperature and climate may further drive a global increase in PAM incidence. A study published in May last year found that PAM infections are on the rise in the northern U.S. ” N. fowleri is expanding northward due to climate change, posing a greater threat to human health in new regions where PAM has not yet been documented,“ the study noted.
Yun Shen, an assistant professor of chemical and environmental engineering at the University of California, Riverside, says that she considers PAM as “a potential emerging medical threat worldwide”. She explains that while warmer temperatures are likely to facilitate the survival and growth of N. fowleri, the risk of exposure may also increase as people indulge in more water-based recreational activities in hotter weather.
N. fowleri is found in warm, untreated freshwater, soil, and dust, says Karen Towne, a clinical associate professor of nursing at the University of Mount Union in Ohio, who co-authored a 2023 study on how the amoeba poses “a new concern for northern climates”. She adds that so far, PAM infections have typically occurred in cases involving swimming, splashing, and submerging one’s head in freshwater lakes, ponds, hot springs, and reservoirs. Meanwhile, less common routes of transmission have included warm hose water, a lawn water slide, splash pad use, and exposure of the nasal membrane to tap water from private well systems.
“Epidemiologically, most cases have occurred in healthy children and young adults⸺more males than females⸺who have had recent contact with untreated fresh water,” Towne told National Geographic in an email interview .
According to Barbara Polivka, an associate dean of research at the University of Kansas School of Nursing, who co-authored the study with Towne, N. fowleri enters the nose via contaminated water, crosses the nasal membrane, and follows the olfactory nerve into the brain, where it incubates for an average of five days. “PAM begins with rapid onset of severe frontal headache, fever, nausea and vomiting, which worsen into stiff neck, altered mental status, hallucinations, coma, and death,” says Polivka.