Chennai: In what has left scientists worried in the United States, a new study has pointed out the presence of brain-eating amoeba, due to changes in climatic conditions.
In a study of Primary Amebic Meningoencephalitis (PAM) infections caused by the Naegleria fowleri amoeba between 1978-2018, researchers found that as temperatures got warmer, the amoeba appears to have spread northwards over the years.
Published in the journal Emerging Infectious Diseases, the study noted that the number of cases of PAM remain stable over the years: Only around 120 PAM cases were reported in the 40-year period. Of these, only 85 patients had eligible or suspected recreational water exposure, while 35 were exposed at canals, puddles, ditches, tap water or at multiple locations.
According to the US Centers for Disease Control (CDC), Naegleria fowleri (commonly referred to as the ‘brain-eating amoeba’ or ‘brain-eating amoeba’), is a free-living microscopic amoeba.
It can cause a rare and devastating infection of the brain called primary amoebic meningoencephalitis (PAM). The amoeba is commonly found in warm freshwater (e.g. lakes, rivers, and hot springs) and soil.
“Naegleria fowleri usually infects people when contaminated water enters the body through the nose. Once the amoeba enters the nose, it travels to the brain where it causes PAM, which is usually fatal. Infection typically occurs when people go swimming or diving in warm freshwater places, like lakes and rivers. In very rare instances, Naegleria infections may also occur when contaminated water from other sources (such as inadequately chlorinated swimming pool water or heated and contaminated tap water) enters the nose 1-4. You cannot get infected from swallowing water contaminated with Naegleria,” the CDC said.
“The rise in cases in the Midwest region after 2010 and increases in maximum and median latitudes of PAM case exposures suggest a northward expansion of N. fowleri exposures associated with lakes, ponds, reservoirs, rivers, streams, and outdoor aquatic venues in the United States. We observed an increase in air temperatures in the two weeks before exposures compared with 20-year historic averages. It is possible that rising temperatures and consequent increases in recreational water use, such as swimming and water sports, could contribute to the changing epidemiology of PAM,” the authors said.
“Although reported incidence of PAM has increased worldwide (12,13), the incidence of reported cases of PAM in the United States remained stable during 1978–2018. The worldwide trends might reflect changes in international diagnostic capacity,” they added.
There appears to be relatively low risk of infection for the amoeba. As the CDC noted, “No data exist to accurately estimate the true risk of PAM. Hundreds of millions of visits to swimming venues occur each year in the US that result in 0-8 infections per year.”
