Schets, FM, van den Berg, HH, de, Zwaan R, van, Soolingen D, and de Roda Husman, AM. The microbiological quality of water in fish spas with Garra rufa fish, the Netherlands, October to November 2012. Euro Surveill. 2015; 20(19):2-8.
In fish spas, clients may submerge their hands, feet or whole body in basins with Garra rufa fish, for dead skin removal. Skin infections may result from using these spas, transmitted from fish to clients, through either fish or water, or from client to client. The microbiological water quality was determined in 24 fish spas in 16 companies in the Netherlands through analysis of a single water sample per fish spa. Water samples were tested for the presence of Aeromonas spp., Vibrio spp.,Pseudomonas aeruginosa, nontuberculous mycobacteria,and faecal indicator bacteria by using standard culture methods. The majority of the examined fish spas contained Aeromonas spp. (n = 24), P. aeruginosa(n = 18), Vibrio spp. (n = 16) including V. cholerae non-O1/O139 and V. vulnificus, and several rapid growing Mycobacterium spp. (n = 23) including M. fortuitum, M.conceptionense, M. abscessus and M. chelonae. Faecal contamination of the fish spa water was low. Based on the detected concentrations of Aeromonas spp., Vibriospp., and P. aeruginosa, the detected Mycobacteriumspp., and the health implications of these bacteria, the health risk from using fish spas is considered limited for healthy people with an intact skin and no underlying disease.
Introduction & Background to Study
For the past two decades, fish spas – where clients immerse part or all of their body into tanks of fish, which nibble on the flakey skin – have become increasingly common, especially in Asia and the Middle East. They are popular in some parts of Europe, too, but reports of bleeding have led many in the public health sector to question the safety of fish spas, and to ban them altogether in much of North America. Skin or even blood-borne infections could be transmitted from person to person, from fish to person, or from tank to person, as a result of sharing fish and tanks without the ability to sterilize them in the normal fashion (lest you would kill the fish). This study attempts to address the infection risks, and focuses on some of the bacteria most commonly associated with these fish and spas.
Materials & Methods
A random selection of 25 companies (wellness centers, beauty spas and fish spas) in the Netherlands were asked by mail to participate in this study; 15 agreed, and additional center was persuaded by the local public health service. Water samples were gathered, often unannounced, according to ISO 19458:2006. Researchers recorded water temperature, pH, turbidity and conductivity. Then they cultured for and quantified Escherichia coli, intestinal enterococci, Aeromonas spp., Vibrio spp., Pseudomonas aeruginosa, and non-tuberculous mycobacteria, using a variety of filtration techniques, selective media, mass spectroscopy and molecular genetics.
A total of 24 spas were tested at the 16 participating companies. The most commonly isolated organisms were Aeromonas spp. (from 24 spas), P. aeruginosa (from 18 spas), Vibrio spp., including V. cholerae non-O1/O139 and V. vulnificus (16 spas), and one or more rapid growing Mycobacterium spp., including M. fortuitum, M.conceptionense, M. abscessus and M. chelonae (23 spas). The intestinal bacteria (E. coli and enterococci) were infrequent (8 spas), and often found in hands-only or feet-only spas. E. coli analyses were seriously hampered by abundant growth of Plesiomonas shigelloides, which may have masked E. coli colonies.
The water temperature in the spas ranged from 25.0 to 33.2 °C, with a median of 28.4 °C. In body spas, the water temperature was generally higher than in foot and hand spas. The pH value of the fish spa water ranged from 6.9 to 8.6, with a median value of 8.1. In all fish spas, water turbidity values of 0.00 Formazine Turbidity Units (FTU) were measured, indicating that the turbidity was very low and below the detection limit of the equipment used. The conductivity ranged from 218 to 1,423 μS/cm, with a median of 432 μS/cm.
All companies filtered the fish spa water, using biological filters with zeolite; the majority had one filter per fish spa installed. Most companies also treated the water with ultraviolet light C (UVC), ozone or both. Almost all companies checked the water temperature on a regular basis, and many used a test kit designed for aquarium and pond owners to test a basic set of chemical parameters, including pH value, hardness, ammonia, nitrite, nitrate, phosphate, iron, and copper. However, keeping a log was not a standard practice, and only 5 of the companies had a laboratory check the microbiological water quality. Water refreshment policies varied from total replacement of the water once or twice a week, to partial replacement of the water every 1 to 7 days.
“Based on the detected concentrations of Aeromonas spp., Vibriospp., and P. aeruginosa, the detected Mycobacteriumspp., and the health implications of these bacteria, the health risk from using fish spas is considered limited for healthy people with an intact skin and no underlying disease.”
The microbial contaminants were not significantly associated with type of spa, water treatment process, water refreshment regime, or physical-chemical parameters of the water.
“The presence of bacteria may depend on occasional contamination of the water by clients and the subsequent expansion of the contamination for prolonged time periods. Most owners could, however, not provide clear figures on spa use in terms of number of users per day; so a relation between intensity of fish spa use and microbiological water quality could not be established.”
Vibrio spp. concentration levels in fish spas were no greater than level in surface water in the Netherlands during that time of the study, suggesting that “Vibrio spp. numbers in fish spas do not pose a major health risk.” “Aeromonas . . . concentrations in fish spas were in the order of magnitude as those typical for rivers receiving sewage discharge.” The rapidly growing mycobactera similarly were of no greater abundance than would be expected in a variety of warm water environments.
“A higher level of faecal contamination could be expected in full body spas, but was not observed. Plesiomonas shigelloides, which appeared to be present in most fish spas and hampered the E. coli detection, is . . . known to disturb E. coli enumeration . . . [and] was not foreseen. . . . We therefore consider the E. coli data unreliable.”
“In addition to establishing microbiological guidelines for fish spas, drafting a code of practice on hygiene in fish spas and risk communication to clients is recommended.”
This reviewer must agree with all of the authors conclusions. The organisms sought and identified in this study should not surprise anyone. They are commonly isolated from environmental and man-made bodies of water, and grow especially well in warm water. Enteric bacteria are so named because they are abundant in the human gut. But they are by no means limited to the gut; they are commonly found on the skin, especially the perineum and nearby surfaces. It is no surprise that they were found in hands-only and feet-only spas; but it is a surprise that they were not more commonly found in the total body spas. Again, the reviewer would have to agree with the authors that the E-coli data may be unreliable due to the unanticipated methodological problems described above.
The authors provided useful comparisons between their fish spa microbiology results and environmental microbial levels published by other groups. It would have been interesting, if not also enlightening, to compare their results with microbiological data from non-fish-containing spa water. Perhaps that comparison will be taken up in a future study.
Although no specific features of the spas or their maintenance were found to be related to the number or species of microbes, it is hoped that this is merely a result of the small number of spas sampled. This type of study must be repeated with a larger sample size in order to identify potentially causative factors that could be altered and/or regulated in order to minimize the water microbiology. If the microbiology of the fish spas is no worse, or greater, than that which could be found in the general environment, why would I or anyone want to see it reduced? If the authors rightly conclude that fish spas pose no increased threat to normal healthy clients above what they might experience in a natural body of water? The reason to minimize risk is that “no increased risk” is not the same as “no risk,” and if we can reduce risk at reasonable cost, we should. And we should, because not everyone is “normal and healthy.” Many people have immunological deficiencies, vasculitis, skin disease, even wounds that they may not know about. Many people are aware that they have diabetes or psoriasis, but may not be aware that consequently they may be at greater risk of infections.
Therefore, while there is no evidence that there is any increased risk posed by the fish spas for normal, health clients, we agree with the authors in recommending the establishment of microbiological guidelines and drafting of a code of practice on fish spa hygiene and risk communication to clients. Identifying spa water quality and maintenance factors associated with the greatest microbial proliferation would make this task much easier and more effective.