Expert in Immunology: Infection by Brain-eating Amoeba Linked to Climate Change

As a Florida transplant, I thought I left the brain-eating parasites behind me when I moved 1,500 miles north to Minnesota, but then it happened: This week a died after contracting the parasite while swimming in Stillwater's Lily Lake. 

The Minnesota Department of Health is still investigating the child's death and Lily Lake has been closed until further notice, but that's hardly an assurance for those like me who swim at least once a week in lakes around the Twin Cities. To get some insight into this illness I spoke with Dr. Mark Schleiss, a professor of Pediatrics in the University of Minnesota Medical School, Associate Chair for Research in the Department of Pediatrics, and Director of the Division of Infectious Diseases and Immunology.

According to Schleiss, it is likely that the organism is living in most bodies of water in Minnesota, including those within Burnsville city limits like .

"Now that it's been demonstrated to be in Minnesota lakes we would have to concede that it would probably be present in any lake," Schleiss said, though he added that unless an infection occured the organism would probably go undetected. "If we had unlimited resources it might be possible to test every lake. Unfortunately, we don't, so that wouldn't be easy to do."

In the absence of a definitive statewide test of all 10,000 lakes, we'll have to stick with the basic facts. 

Q: What is it? 

A: "From my understanding, final identification is still pending but it's almost certainly Naegleria fowleri, an amoeba, a parasite that lives in fresh water. It is not new. It's been around for a long time. It is described as the cause of an infection that is almost always fatal." 

Naegleria fowleri causes a disease formally known as primary amebic meningoencephalitis (PAM), an infection that leads to the destruction of brain tissue. 

Q: Where is it found? 

A: Naegleria is commonly found in freshwater all over the world, though it seems to thrive especially well in warmer temperatures. According to a fact sheet by Stanford University, the organism has been found in soil, swimming pools, cooling towers, hospital hydrothermal pools, and sewage sludge. A free-living amoeba can survive outside of a human host as long as the conditions remain favorable. Infections due to Naegleria fowleri occur all over the world, but are most frequent in tropical areas and during hot summer months. 

Q: How is it contracted? 

A:  "It's important to underscore that you can't get it by drinking lake water. The infection begins after migration of amoeba across the thin, bony plates of the nasal cavity into the brain."

In other words, the amoeba can enter the brain if you take a slug of lake water up the nose while diving or swimming. 

Q: How often does this happen?

A: "This is rare. There have only been 40 to 50 cases in the last 10 years. When you think of all the freshwater recreation that goes on, the fact that this is so rare provides at least some reassurance that the likelihood of infection is extraordinarily low."

According to the Center for Disease Control, four people died after contracting Naegleria fowleri  in the summer of 2011 (these cases occurred in Virginia, Florida, Kansas and Louisiana). Prior to this week, the CDC has only one infection on record in Minnesota—a fatality that occurred in August 2010, which was also linked to Lily Lake.

Q: What are the symptoms? 

A: It's not easy to diagnose, according to another doctor cited by ABC News. Symptoms include headache, fever, nausea and a stiff neck. In time, these symptoms will give way to confusion, seizures and hallucinations. Death typically occurs within 12 days.

Those who suspect that they may be infected should act quickly.

"It's important for parents to know that if their children have signs or symptoms if illness, especially headaches, fevers, anything at all like that they should seek medical help immediately," Schleiss said. 

Q: What treatment possibilties are available?

A: "There is a treatment called amphotericin," Schleiss said. "The problem is that the disease is so rapid and aggressive that by the time diagnosis is made it's too late to make a difference, although there are occasional reports of survival." 

Q: Is it possible to survive? 

A: Theoretically, yes, though death rates are over 98 percent, Schleiss said. According to the CDC, only one person out of 123 infected in the United States between 1962 and 2011 survived.

Q: How can you protect yourself?

A: "The only way to avoid it with certainty is to avoid swimming and diving in fresh water lakes," Schleiss said.

In a statement issued Tuesday, the Minnesota Department of Health said the health benefits outweigh the risk of contracting this organism. The department advised swimmers to avoid swimming in "obviously stagnant water when temperatures are high and water levels are low." Officials at MDH also suggested that swimmers protect themselves by keeping their heads out of water, plugging their nose with clips, and staying away from shallow water. Swimmers should also avoid stirring up sediment at the bottom, where the organism could be concentrated. Schleiss said these measures could offer some protection, though none are proven to be effective. 

Q: Can this affect pets as well?

A: The jury is still out on this one. 

"I'm not aware of any infections in animals. That's an interesting question," Schleiss said. "I don't know why the dog brain would be any different. If it is possible, the likelihood is low."

Q: Why is this happening? 

A: "It is unusual is to see (Naegleria fowleri infections) this far north, and this is the second case in three years. It is remarkable a shift in the organism's epidemiology. The overwhelming reason for this is man-made climate change. We've seen a remarkable and striking shift in temperatures in freshwater lakes and streams and all over the upper Midwest. Freshwater fish are dying in almost biblical fashion and temperatures are ranging 15 to 20 to 25 degrees above the baseline rates of past century. This is because of an increase in carbon-based emissions and the attending climate change we're living through right now.

This is not the only infectious disease related to these kinds of issues we've seen. We had a child death a few years ago from Rocky Mountain Spotted Fever, a bacterial infection spread by ticks. That's a bit of a misnomer since it's actually been pretty rare in the Rocky Mountain states. It was unheard of in Minnesota before, only seen in the southern states. With the change in climate we're seeing a change in kinds of microorganisms in our niche, and that brings new, novel diseases to Minnesota. Unfortunately,  this is an infection we'll be seeing again in the future. 

We're in uncharted water here, no pun intended, and the best we can do is watch carefully. We need to understand what is happening. The good news is that the risk of contracting (Naegleria fowleri) has been very low, even in southern states where it has been endemic for years."

Any other questions? The CDC has a helpful FAQ section about this illness.