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Roy Vore, Ph.D

Louis “Sam” Fruia, CPO, AFO

Recreational Water Illnesses (RWIs) in Spas

This is the second in a series of articles on recreational water illnesses (RWIs). This article focuses on RWIs in spas.

Spas are not small, hot swimming pools. The design of spas leads to a pattern of RWIs that is unique from that of pools. The design elements are the physical water parameters, the mechanical design of the circulatory systems, and the behavioral pattern of the bathers. Once we understand each of these elements, we will be better prepared to control RWIs.

The majority of public and semi-public spas in the United States are stand-alone systems. These units have their own filtration and circulatory systems. This design allows the operators to maintain a water temperature 10°F to
30°F greater than those of a pool. The separate pumps allow a rapid turnover of 30 minutes or less. The total volume of water in freestanding spas is much smaller than in pools. You measure this several different ways; they translate into more bodies per gallon of spa water. The downside of this is that organic material shed by bathers (perspiration, body oils, urine, feces, and cosmetics) is much more concentrated in spa water than in pool water. When you crank up the heat to 104°F, you can see why your 2-3 ppm chlorine residual may not last long enough to see the filter twice. These organic compounds, coupled with the near-neutral pH and high temperatures, make spas an ideal breeding ground for many bacteria, including at least one that does not grow well in swimming pools. Consider this: Stir six people every 15 minutes every hour into a steamy 450-gallon pot, and you will have 20-percent human pathogen soup by the end of an eight-hour day. If you follow the accepted water replacement guideline for a spa, you would be required to replace the spa water every day. The body waste produced is equivalent to 5,500 swimmers actively swimming in a 220,000-gallon pool during the same eight-hour period.

The second factor to consider with RWI exposure in spas is the mechanical design of the facility. Spas have jets or blowers, whereas pools seldom do. These systems create aerosols. Anything in the water can be carried into the air around the spa. If the spa water contains pathogens, the jets can send mist droplets containing these pathogens into the breathing zone of the spa users. If the droplets are the correct size, they can be inhaled into the lung. This is how bacteria such as Legionella can enter the lungs and cause an infection. If the individual is immune-suppressed by disease or age, the infection can be fatal. Under some conditions, droplets may be carried considerable distances from the spa. This is why the air-handling capacity of your spa area is important, too, so please refer to your state codes or to BSR/APSP-11 Standard for your application.

A third key difference is the behavioral pattern of the bather. This pattern can be seen by casual observation. Bathers in pools are active and often have their heads in or under the water. While swimming in a pool, bathers are more likely to ingest water. The ingestion creates an entry point for a pathogen to gain entry to the human body, increasing the person’s susceptibility to illness caused by a pathogen. It is quite common to observe swimmers spitting out mouthfuls of water upon surfacing. Bathers in spas are passive. This pattern of spitting out mouthfuls of water is seldom seen in spas. There is an exception to consider: Competitive divers also use spas during their events to relax and to reduce muscle fatigue caused by the competition or practice so, in this instance, the participants’ contribution to the pathogen soup is increased. Despite the exceptions, Acute Gastrointestinal Illness (AGI) is seldom reported in spas. This is in contrast to pools, where the single-largest group of RWIs is gastrointestinal. It is quite likely that the bacteria and parasites that cause AGIs are at high levels in spa water. The lack of AGIs in spas is quite understandable when the behavior of the users is considered. Rashes are the predominantly reported RWI in spas. Rashes are also reported in pools, but are not as prevalent as in spas.

RWIs in spas can be broken down into two categories: rashes (dermal infections) and respiratory infections (see Table 1). The latest summary of U.S. RWIs was for 2003-2004 and was published by the CDC in December 2006 (available at www.cdc.gov/mmwr/preview/mmwrhtml/ss5512a1.htm).

Table 1 – Summary of RWIs Associated with Treated Spas

Rashes: Pseudomonas aeruginosa is the cause of nearly all microbial rashes. This bacterium is commonly found in natural and potable water. P aeruginosa can readily grow on hundreds of different organic compounds. These include cosmetics, body oils, perspiration, and urine. It grows optimally between pH 5.0 and 8.5. In short, an ideal man-made habitat for growing P aeruginosa is a spa. Because swimming pools have less organic load and are cooler, they are not quite optimal, but they still allow abundant growth of P aeruginosa.

The biggest complaint with Pseudomonas infection is an itchy rash. In many cases, the affected areas are those covered by the bathing suit. This is especially true for women. Bacterial rashes are noted one to 14 days after exposure. Chemical irritants, especially chloramines and bromamines, more likely cause rashes that occur within 24 hours of exposure. Nearly all Pseudomonas-caused rashes disappear on their own and do not require medical treatment. Such rashes are described as “self-limiting.” Risk factors for infection include the duration of exposure, pre-existing skin abrasions, type of swimsuit worn, number of bathers present in the water, and individual susceptibility differences. Children and adolescents are more likely to develop rashes than adults in pools. This is because kids spend hours in the water, and adults are more likely to take a quick swim and then lay on the deck next to the pool. Women are more likely to get rashes than men. Women’s swimsuits tend to be lined and dry slowly next to the skin. Men’s swimsuits tend to be loose and unlined and dry rapidly. The number of bathers in the water is probably related to loss of sanitizers through bather loading. When there is a pool or spa party, the bathers introduce large amounts of organic contaminants (perspiration, suntan lotion and cosmetics, traces of urine and feces, skin cells, etc.). These organic contaminants create an instantaneous demand for chorine and bromine. Once the sanitizer level drops below a critical concentration, there is no way to control bacteria.

Staph has been a historical concern in older literature. Since the mid-1980s, most rashes have been attributed to Pseudomonas aeruginosa. This change in reported etiological agents corresponds to a rise in case studies of rashes and to the simultaneous development of the modern portable spa. In the most recent CDC summary of RWIs, a single incident of Community-Associated Methicillin Resistant Staphylococcus aureus (CA-MRSA) was documented. This case occurred in a high school physical therapy whirlpool. The reality is, however, that athletic trainers, coaches, or team doctors are not trained to make the aquatic links to an RWI pathogenic infection such as CA-MRSA because it is not part of their training – so the origination of an RWI outbreak could go undetected or be misdiagnosed.

Respiratory Illnesses: Legionella is a potentially fatal bacterium that has caused numerous outbreaks in spas. The bacteria are small enough to pass through spa filters. Studies indicated that Legionella are found in at least 40 percent of natural freshwater streams, rivers, and lakes. In nature, Legionellae grow in close association with other microorganisms in biofilms. The optimal temperature for growth is 106°F. Operating conditions inside cooling towers, humidifiers, domestic hot water systems, and spas are similar to the natural habitat of Legionella. When these systems are not properly maintained, bacteria can develop into large colonies. Presently, more than 50 species have been identified. Approximately 90 percent of all cases are caused by one species: Legionella pneumophila.

Illness caused by Legionella varies from the severe form of Legionnaire’s Disease to the mild and self-limiting Pontiac Fever. Legionnaire’s Disease is a severe and progressive pneumonia. Symptoms include fever, chills, and a cough, which may be dry or produce sputum and may include muscle aches, headache, tiredness, loss of appetite, and occasionally diarrhea. Approximately 5 percent of those exposed become infected. The incubation period is two to 10 days. Risk factors for Legionnaire’s Disease are lung disorders, diabetes, cancer, kidney disease, AIDS/HIV, age older than 50, and heavy drinking. The highest fatality rate occurs in health care facilities, where patients already have predisposing conditions. Pontiac Fever is a mild infection and has symptoms similar to the flu. Individuals recover quickly from Pontiac Fever, usually within two to five days, and do not require medical treatment. Symptoms of Pontiac Fever include fever and muscle aches without pneumonia. It is estimated that >95 percent of those exposed become infected. Pontiac Fever has acute onset with an incubation period of 36 hours. There are no known risk factors for Pontiac Fever.

How many outbreaks of Pseudomonas and Legionella are there? We don’t know. Anecdotal evidence strongly suggests that Pseudomonas rashes are very common. The World Health Organization (WHO) has documented at least 50 outbreaks of Legionella in spas on cruise ships alone.

Simply maintaining the sanitizer levels at all times can prevent outbreaks of Pseudomonas and Legionella. Chlorine and bromine concentrations of 1 ppm or greater will kill either bacteria rapidly. Some facilities maintain the sanitizer only during periods of operation. This effort to reduce operating cost is ill-conceived. When the sanitizer drops to less than 1 ppm, bacteria are able to multiply rapidly. Both Pseudomonas and Legionella can form biofilms (slime layers) that protect the cells from the sanitizer. In subsequent periods of heavy use, the sanitizer level in the water can drop, and then any bacteria liberated from the biofilm will be able to cause infections. Maintaining the sanitizer concentration at all times, even in periods when the spa is not open for use, eliminates the potential for biofilm formation by these two bacteria.

How can you detect that a spa is contaminated and the source of an outbreak? A visual examination of the spa and a review of the maintenance logs are the first steps. Cloudy water and foam that won’t dissipate rapidly are strong indicators of high levels of organic contaminants. Organic contaminants deplete the sanitizer and provide nutrients for bacteria. If the sanitizer level has been less than 1 ppm for six or more hours, it is likely that bacteria are present. Check for a repeating pattern of under-dosing while the facility is not open for use. Spas should never be slimy. Slime is an indication of microbial growth.

Much more information on RWIs is available on the CDC website at www.cdc.gov/healthyswimming.

Louis Sam Fruia, Aquatic Administrator
Brownsville Independent School District

Roy Vore, Ph.D., Research Microbiologist
DuPont Chemical Solutions Enterprise

Dr. Vore is a senior microbiologist in the Clean and Disinfect division of DuPont’s Chemical Solution Enterprise. Over the last 15 years, he has concentrated most of his work in the microbiology of swimming pools and spas. Dr. Vore has more than 30 scholarly papers and presentations on the microbiology of swimming pools and spas. He has been an active participant on the APSP’s Recreational Water Quality Committee since 1996.

Mr. Fruia is aquatic administrator with Brownsville Independent School District, one of the largest school districts in Texas whose aquatic facilities have been recognized for “Aquatic Excellence” by the National Recreation and Park Association and “Best in Aquatics” by Aquatics International under his direction. During the last 30 years, his diversified aquatic experience includes coaching, CPO/AFO/APSP Instructor, aquatic operator, and developing/presenting RWI training modules. Mr. Fruia advocates including RWI training at all levels of aquatic training and is an active member of APSP’s Recreational Water Quality Committee, Service Council, Service Education Committee, vice chair of Hot-Tub Task Force, and a member of the Provisional Organizing Committee of the APSP Career Institute.

© 2007 by The Association of Pool & Spa Professionals. All rights reserved. No part of this publication may be reproduced or transmitted without written permission.