Unfortunately, Naegleria fowleri, more popularly known as the "brain-eating amoeba," is in the news again. Sadly, the latest case is a 9-year-old Kansas girl that died recently from N. fowleri infection. It’s still an extremely rare disease but it’s still a significant concern because infection is almost always fatal.

Naegleria fowleri is a single-celled organism that lives in fresh water, and likes it warm. It grows fastest to 42C (~107F), but about 25C (77F) or higher is warm enough for the amoeba to reproduce. That’s why most cases have been identified in Florida and Texas, and there are concerns that climate change may help expand its range.

People are infected when water contaminated with the organism enters the nose. Not surprisingly, most people are infected while swimming or diving in lakes and rivers. After entering the nose, the amoeba makes its way to nerves and then migrates to the brain, where it essentially "eats" brain cells. Death usually occurs a few days after the onset of disease.

Since people aren’t the only ones exposed to water, a logical question is can other species be infected by Naegleria fowleri? More specifically, can dogs be infected? Many dogs spend a lot of time outdoors and in the water, and could therefore be exposed.

For example, a couple of weeks ago, we were at a cottage for vacation. Our dog Merlin is a pathetic excuse for a Labrador since he’s too chicken to swim, but he still likes to wade in the lake and stick his nose in the water. So, what’s the risk to him (ignoring the fact it’s still up in the air whether he has much of a brain to target)?

Can dogs be exposed?
Certainly, dogs can be exposed to the amoeba. If it’s in the water and people can be exposed, there’s no reason dogs would be any different in that respect. The risk of exposure varies greatly by geographical region. Around here, the risk would be exceptionally low given the water temperature. So, Merlin and his microscopic brain are presumably safe. Even in warmer waters, the risk of exposure would still likely be very low.

Can dogs get sick?
We don’t know. A few different animal species are known to be susceptible, but there are no reported canine cases (yet). The disease is very rare in people, and a person is much more likely to get diagnosed than a dog, in which testing would be less common. It’s also not an easy infection to diagnose and it would require testing of the brain after death. Most dogs that die of neurological disease don’t get tested for something like this. So, I don’t think we can rule it out, but I also don’t think it’s a high-risk situation.

Should anything be done?
It’s hard to say. It’s a rare to non-existent problem in dogs. My general line is that common sense must prevail, but you never want to be the first case of something. Thinking about the risk of disease, what can be done and whether those measures have a realistic chance of doing anything is the key.

Here’s what’s typically recommended for people:

  • Use nose clips when in high-risk waters (not going to happen for dogs)
  • Avoid putting your head under water in high-risk areas (ditto)
  • Avoid stirring up sediment in the water (also probably not going to happen)
  • Avoid going in the water during periods when water temperatures are high (this one’s practical)

Bottom line for me: life carries some degree of risk. We have to live with that and we can’t eliminate it all. The lack of evidence that this is a significant problem makes it hard to recommend any disruptive measures.

If Naegleria fowleri is known to be present in a water supply, stay away (for you, as much as the dog). Beyond that, enjoy the summer.