How the climate crisis is fueling the spread of a brain-eating amoeba | Environment death of a child in Nebraska this summer he put the rare but deadly Naegleria fowleri – more commonly known as a brain-eating amoeba – back in the headlines. The amoeba lives in warm, cool water and can enter the body through the nose, where it travels to the brain and begins to destroy tissue.

The case highlighted a troubling new reality: Climate change is encouraging the emergence of the amoeba in parts of the United States where it is not typical, such as the north and west.

Naegleria it grows best in warm waters – temperatures above 30 ° C and can tolerate temperatures up to 46 ° C, says Charles Gerba, a microbiologist at the University of Arizona. This makes it suitable for spreading in a warm climate.

“They like warm surface waters during the summer in the northern latitudes,” he says.

Amoeba causes a disease called primary amoebic meningoencephalitis, and although getting sick is rare – between 2012 and 2021, only 31 cases were reported in the United States, according to the Centers for Disease Control – is incredibly lethal. According to the CDC, only four out of 151 people survived the infection between 1962 and 2020.

In the United States, Naegleria it has typically been confined to the southern states, but has spread steadily northwards in recent years. A 2021 study showed that while the infection rate hasn’t changed, the amoeba is moving from the southern states to areas of the Midwest. It was found as far as Minnesota.

Outbreaks have mostly been associated with swimming in lakes, although an outbreak in Arizona resulted from the use of warm groundwater where Naegleria it was growing in a well. Previous cases have also shown people contracting the infection through contaminated water used to slip and slide in the yard or perform nasal irrigation.

Nebraska health officials said a child died from a rare infection caused by a brain-eating amoeba after swimming in the Elkhorn River in eastern Nebraska. Photography: Chris Machian / AP

The pathogen was first discovered in Iowa this summer after someone died in a popular lake. A nearby weather station recorded high temperatures of around 35 ° C (95 ° F) for two consecutive days during the July 4th holiday, when the swimmer is believed to have contracted the amoeba.

Gerba adds that most of the cases involve males under the age of 18, although it is not clear why. Boys may be more likely to participate in activities such as diving into the water and playing in the sediments at the bottom of lakes and rivers, where the pathogen is likely to reside.

Although amoebas do not cause death, they can cause serious damage. In one alleged Naegleria case in Florida, a teenager had a fever after swimming in brackish water, was later hospitalized and suffered a seizure, according to a GoFundMe set up to support his care.

Warmer temperatures not only facilitate the survival and growth of pathogens such as Naegleriathey also push people into the water more, which can increase their risk, says Yun Shen, an environmental engineer at the University of California Riverside.

The climate crisis is also exacerbating extreme weather events, such as floods and droughts, which can introduce more pathogens into the environment. “In drought areas, pathogens will be concentrated in water bodies, which could increase the dose of exposure to pathogens when humans are in close contact with water bodies,” says Shen. In flooded areas, water can transfer pathogens into the environment: for example, a flood could carry pathogens from the soil or aquatic environments to homes and buildings, or cause wastewater collection to overflow and vomit pathogens in the environment.

“In the future, due to climate change, people living in cold regions may also be exposed to warmer climatic conditions and a greater chance of being exposed to pathogens,” says Shen.

A photomicrograph provided by the Centers for Disease Control and Prevention (CDC) describes the characteristics associated with a rare brain infection due to Naegleria fowleri.
A photomicrograph provided by the Centers for Disease Control and Prevention (CDC) illustrates the characteristics associated with a rare brain infection due to Naegleria Fowleri. Photograph: CDC / Reuters

Understanding where the pathogen lives is difficult because there is no quick test for its presence or abundance in any body of water. And even more frustratingly, it’s still unclear why some people get amoeba and others don’t, says the CDC. After all, hundreds of millions of people swim in fresh, warm water every year, and only a handful get infected. This makes it difficult to create acceptable levels to regulate.

As experts continue to observe these changes, Djerba recommends some precautions for swimming in natural fresh waters. It is best to avoid putting your head underwater to prevent water from getting into your nose in warm, freshwater areas. Another option is to wear nose clips, especially for children, she says. The mud and soil in these areas can also get infected, so experts say avoid digging or disturbing the sediments.

“As surface water temperatures rise further north, we expect more cases in the future,” says Gerba. “I expect this trend to continue.”

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