Ichthyotherapy is a fancy name for sticking your feet in a bucket of doctor fish (Garra rufa) and letting them gnaw on your dead skin. While it’s not something I’m planning on doing (for various reasons), it’s a popular spa treatment in some areas. It’s also spawned (pardon the pun) controversy because of infectious disease concerns. Specifically, spa "instruments" are supposed to be cleaned and sterilized between clients, but you can’t really autoclave fish. (Well, you can autoclave fish… just don’t expect them to do any more foot grazing when you’re done.)

Some people have pushed back, saying there’s no evidence that these fish pose any risk, although some infections have been reported. A paper published in the latest edition of Emerging Infectious Diseases (Verner-Jeffreys et al. 2012) provides some interesting new information. It involves an investigation in 2011 by the UK’s Fish Health Inspectorate into an outbreak of disease amongst 6000 doctor fish that had been supplied to spas in the UK. The outbreak had a high mortality rate (amongst the fish, not the spa clients) and the bacterium Streptococcus agalactiae (a Group B Streptococcus species) was isolated from sick and dead fish. This bacterial species can cause a range of illnesses in people, but the strain that was found was most closely related to a strain previously found in a sick fish and is not necessarily a risk to people. However, it raised questions about the bugs that may be found in these fish.

Researchers followed this up by doing checks of doctor fish arriving at Heathrow Airport from Indonesia. A variety of different bacteria known to cause disease were isolated from the fish, including some multidrug-resistant bacteria. While it’s not particularly surprising, this provides more evidence that most or all of these spa fish are carrying bacteria that can cause disease in people. When people put their feet in water containing these fish (and the fish feces), there’s a chance of exposure. Disease seems to be rare, but it can happen, and the risk is probably highest is people with underlying skin disease, as well as people with compromised immune systems.

The easiest way to avoid these risks is to avoid ichthyotherapy. But, if you can’t go without your foot fish treatment, how can you reduce the risk? There’s no solid information but the following precautions and measures make sense:

• People with cuts, scrapes or other foot lesions should not undergo ichthyotherapy.
• People with diseases that affect their immune system (including diabetes) should similarly avoid close encounters of the fishy kind.
• Consideration should be given to commercially raising pathogen-free doctor fish for spa use under high standards of infection control and hygiene.
• Good management practices to deal with cleanliness of water and health of the fish should be developed and followed.