The Baton Rouge Water Company received a clean bill of health after its system was tested for the potentially fatal Naegleria fowleri amoeba that has killed three people in Louisiana since 2011.

As part of a larger program to test water systems across the state for the amoeba, which attacks brain tissue, the Baton Rouge Water Company got its turn this summer.

“We were a little concerned. You never know,” said Patrick Kerr, president and CEO of the Baton Rouge Water Company.

However, testing by the state Department of Health and Hospitals found no trace of the amoeba in five selected locations of the water company’s system.

Two other systems in the state weren’t so fortunate.

The amoeba was found in the St. John Water District 1 in the Garyville/Reserve area and the Ebarb Water District 1 Aimwell area in Sabine Parish, said Jake Causey, chief engineer and safe drinking water administrator with DHH.

Each of those water systems did what is called a “chlorine burn,” which means the chlorine being put through the system was increased for 60 days to 1 mg/liter. That’s high enough to kill off the amoebas while still being far lower than the 4 mg/liter limit EPA has set for chlorine in drinking water, Causey said.

In 2011, two people in Louisiana — one in St. Bernard and one in DeSoto parish — died after being infected by the Naegleria fowleri amoeba. The amoeba infected their bodies through the nose by way of a neti pot, a popular home remedy thought to help clear sinuses.

In 2013, a child playing on a slip-and-slide in St. Bernard Parish died after water infected with the amoeba got into the child’s nose.

DHH worked with the U.S. Centers for Disease Control and Prevention to come up with a collection technique to search for the amoeba in other water systems in the state, Causey said.

This spring and early summer, DHH worked with a contractor to devise a method, which was used throughout the summer to test 28 water systems, Causey said.

“It’s just not something that’s been looked for before,” he said.

Considering there are almost 1,400 water systems in the state, 28 may not seem like much, but the method to look for the amoeba is time-consuming. It takes almost an hour to catch one sample, he said, and each water system is tested in five locations: the source of the water and then points along the distribution system. The analysis of those samples takes another two weeks.

Causey said DHH continues to work with CDC to try to find quicker testing methods.

As an additional precaution, DHH passed an emergency rule that required all water systems to increase the amount of residual disinfectant in their water by Feb. 1, 2014. Before the emergency rule, water systems had to keep a detectable level of chlorine at all locations. The new rule raised that to 0.5 milligrams per liter, a level that kills the amoeba.

Testing for the Naegleria fowleri amoeba ended for the year in October, mainly because the amoeba likes warm water and generally falls back during the colder months. Testing of additional water systems will likely resume next year in May or June, he said.

Although this naturally occurring freshwater amoeba is nothing new in water and soil in the United States, infections are rare. According to DHH, from 2003 to 2012, there were 31 reported cases of the infection in the United States.

“It’s been around forever. It’s naturally occurring in warm soils and water,” Causey said.

A person can’t be infected with Naegleria fowleri by drinking the water. Instead, infection occurs when infected water goes up the nose, usually through swimming or irrigating sinuses with tap water.

The amoeba travels from the nose into the brain, where the infection causes brain tissue to die.

Symptoms can include headaches and fever and then confusion, loss of balance and even hallucinations. The amoeba usually causes death within about five days. According to CDC, only three of the 132 people known to have been infected with the amoeba in the United States in the last 50 years have survived.

“It’s a very rare infection and the risk is very low, but it does have high consequences,” Causey said.

Follow Amy Wold on Twitter, @awold10.