On an extremely hot day in the middle of summer it’s very common to see people swimming in the lake or playing at the beach. Most people are there for fun relaxing and lounging and nobody is concerned about getting sick.
But deadly microbes love this hot environment and strive when water levels are low and water temperatures are high. Parasites that are dormant when water temperatures are below 80°F become active when temps are high and can infect people swimming in the warm water.
Jack Ariola Erenberg was a nine-year-old boy from Stillwater Minnesota playing with his family and friends near his home in the warm waters of Lily Lake, just like so many other children have for years, when he was unknowingly infected by primary amoebic meningoencephalitis (or PAM). On August 7, 2012 the infection killed Jack after ravaging his brain and leaving him in a coma. The town later investigated the lake with the help of the state health department and the CDC to determine if the amoeba was present.
Primary amoebic meningoencephalitis is a very rare infection caused by amoeba that live in warm stagnant water of inland lakes. Only 123 cases have been reported in the United States since 1962. The parasite that causes it, Naegleria fowleri, is common and has been found to infect people by traveling through their nose to their brain.
Reported cases of infection from Naegleria fowleri demonstrate that it can be found in poorly chlorinated swimming pools, dirty tapwater, or in adequately cleaned soap dispensaries, according to the Centers for Disease Control and Prevention.
Most of the cases reported in the United States are in the southern states during summer and involve swimming or playing in freshwater lakes. Water temperatures are usually high and there has typically been prolonged drought causing water levels to be lower than normal.
Symptoms of Primary Amoebic Meningoencephalitis
After becoming infected with PAM, people usually show signs of bodily aches like stiff neck and joints, confusion, loss of balance, difficulties focusing, seizures, and hallucinations. These symptoms typically show between one and seven days after infection.
PAM is known to infect children and adults and there are no indications that persons in good health are less likely to be infected nor that poor health is a contributing factor.
From the time when the amoeba enters the body, PAM can take anywhere from 2 to 12 days to kill the infected person.
Risk of Getting Primary Amoebic Meningoencephalitis
The risk from Naegleria is very low, and in the case of Jack Ariola Erenberg’s death the state of Minnesota was concerned but wanted to quell public anxiety and avoid panic. The Minnesota state epidemiologist, Richard Danila, released a statement stating: “We do not want to discourage people from swimming. Rather, simply avoid swimming, diving, or other activities in obviously stagnant water while temperatures are high and water levels are low.”
Lily Lake has been identified as the source of Jack’s infection. In 2010, Annie Bahneman died from the same sort of infection just days after she was swimming in Lily Lake. The Stillwater Minnesota Administrator Larry Hansen and Mayor Ken Harycki were not told about Annie’s death two years ago because of the rarity of the disease, and the fact that it was found so far north during an unusually hot summer. The Minnesota Department of Health said the 2010 investigation took several months to conclude the source of Annie’s infection.
Officials have now decided to close Lily Lake and are working with the local stakeholders to determine how long the beach will be closed and future plans for the lake.
Amoeba cannot be transported from one lake to another on the bottom of boats, the infection is not contagious, fish caught in lakes are safe, and dogs swimming in the lakes are not affected by the amoeba.
Lakes cannot be treated to kill the bacteria or amoeba that cause the infection that killed Jack and Annie. They are part of a microscopic ecosystem that exists in all freshwater lakes.
Your best options to avoid risk are to swim in lakes or rivers whose water temperature is below 80°F as Naegleria fowleri go dormant in cooler water temps.