A marine microorganism has been spotted in coastal waters of New South Wales that causes blinding infections in one in four swimmers.
Acanthamoeba, a microscopic life form, feeds on cells in the eye, causing inflammation and, in rare cases, irreversible damage.
If the pathogen is allowed to spread to the cornea, the clear outer layer at the front of the eye, it can cause an infection called acanthamoeba keratitis.
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The drug-resistant pathogen can cause vision loss, with one in four affected individuals losing less than 25 percent of their vision or becoming blind.
Researchers from the University of New South Wales said that while the condition is rare, swimmers who wear contact lenses are at an increased risk.
In 2019 and 2020, multiple water samples were collected from four popular bathing spots to measure the levels of the microorganism.
Acanthamoebas were included in samples from all four coastal sites, with a total of 38 percent of samples being positive.
The more urbanized sites had higher positive samples, some recording greater than 50 percent contamination.
The least urbanized sites had 32 percent contamination.
The results, published Thursday in Science of The Total Environment, suggest that the sites’ proximity to urban areas could lead to increased water pollution and potentially encourage acanthamoeba growth.
Study author Binod Rayamajhee of UNSW Medicine and Health said pollutants such as sewage, animal droppings and rainwater could create a better breeding environment.
“The contaminated water allows the acanthamoebas to thrive as they feed on the nutrients and a variety of bacteria,” Rayamajhee said.
Acanthamoebas have also been found to be more prevalent in summer.
In January, 65 percent of the samples were positive, in September it was only five percent.
“There are more cases in the summer, when recreational activities are likely to be at their highest,” Rayamajhee said.
“No one should panic. But the best thing people should do is take off their contact lenses and never mix them with water from any water source.”
The study was a collaboration between UNSW Sydney, the University of Technology Sydney and the University of the West of Scotland.