Experts are worried that a microbe that rarely but sometimes finds its way into human brains is moving out of its normal range in the south toward the north. Once in the brain, the amoeba destroys brain tissue and causes swelling and inflammation. The amoeba is naturally found in warm freshwater, but with climate change increasing temperatures it has been found in Midwestern states further north than in the past.
A new study set to publish in Emerging Infectious Diseases in January reports that the amoeba may be expanding its geographical range. The authors looked at cases of primary amebic meningoencephalitis (PAM) caused by the amoeba Naegleria fowleri between 1978 and 2018. It gets into the brain through the nose and does not cause infection if swallowed. However, PAM is very rare, with only 34 cases in the last 10 years, according to the Centers for Disease Control and Prevention (CDC).
The amoeba can be found in water and prefers warm temperatures up to 113 Fahrenheit, which is why experts think its spread north may be linked with climate change. The study found that according to their estimates there were increases in air temperature the two weeks before exposure and that coinciding with increased recreational activity in water may be affecting how the amoeba spreads and the increase in PAM cases.
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PAM is usually fatal. The most recent cases were at Lake Jackson in Texas, where a six-year-old boy was infected and died from it, and in Florida where a 13-year-old boy got infected. But there may be some hope that it is not always fatal as there is at least one case where it was treated with antibiotics.
The researchers found that the maximum latitude for PAM cases shifted about 8.2 miles northward each year of the study. Thankfully, it doesn’t seem like the number of cases of PAM are increasing, according to the study. “Our results show a suggested northward expansion of PAM and its potential association with higher temperatures warrants further investigation,” write the authors.
But if the amoeba continues to spread north into more bodies of water, that could potentially lead to more cases. “There is concern if waters continue to warm in northern states there may be more of a risk to people who go in water in those states,” says CDC epidemiologist Jonathan Yoder to Insider.
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