The deadly Naegleria fowleri amoeba was found in the water system of St. Bernard Parish in Louisiana. (Getty)

A 4-year-old child has died after he contracted a deadly amoeba that was found in the water supply of St. Bernard Parish, La.

The boy died of encephalitis, swelling of the brain, as a result of contracting the Naegleria fowleri amoeba. The deadly amoeba causes primary amebic meningoencephalitis (PAM), a brain infection that leads to the destruction of brain tissue.

The Naegleria is found in warm freshwater and can cause a deadly infection if inhaled through the nose.

The child was playing on a slip n'slide in St. Bernard Parish when he contracted the pathogen, according to a spokesman from the Louisiana Department of Health and Hospitals. Water tests found the amoeba was present in the hose used to spray the slip n'slide.

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People who contract that amoeba are often exposed while swimming in freshwater lakes or rivers. In rare cases they can contract the pathogen if they swim in under-chlorinated water or use a neti pot.

According to the Centers for Disease Control and Prevention, there have been only 128 known infections in the United States in the past 50 years. Just three people have been known to have survived that particular form of parasitic meningitis.

The unnamed child is the third child known to have been infected with the amoeba in the U.S. this summer. Zachary Reyna, a 12-year-old boy from Florida, died after being infected with the parasite last month.

In Little Rock, Ark., Kali Hardig, 12, survived the infection and was released from hospital last week.

After finding the Naegleria fowleri amoeba, St. Bernard Parish officials started flushing out the town's water supply with chlorine to kill the pathogens.

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"The water is safe to drink and there are basic precautions that families can take, such as chlorinating their pools and avoiding getting water in their noses, to protect themselves," State Health Officer Jimmy Guidry said in a statement. "Though infection from this amoeba is very rare."

The Associated Press contributed to this report.