Disease outbreaks involving public whirlpools have been reported frequently since their use has become popular in recent years. Because public whirlpools are often used by persons who have only transient contact, infections resulting from their use are difficult to identify, and published reports probably represent only a small portion of a larger public health problem. Most published outbreaks have reported Pseudomonas aeruginosa contamination of the whirlpool as a result of failure to operate the pool according to recommended practices. Maintaining the microbiologic quality of whirlpool water and preventing infection absolutely require regular operation and maintenance, including monitoring and record keeping by qualified personnel.

The growing popularity of heated pools, especially whirlpools and hot tubs, has been accompanied by increasingly frequent oubreaks of an illness produced by Pseudomonas aeruginosa. The illness usually includes folliculitis, pruritic skin rash, and/or otitis externa and occasionally mastitis and systemic symptoms. Although usually self-limited, rare severe cases have been described. Motel and hotel whirlpools are most often implicated as the source of outbreaks. The relative importance of pool conditions and the bacteriology of P. aeruginosa in the pathogenesis of this illness remain to be elucidated. Implementing CDC Guidelines for public spas and hot tubs seem the most reasonable way of reducing the risk of large outbreaks. Prevention of cases arising from home hot tubs or whirlpools will be very difficult and may depend on extensive public education or the development of simple, inexpensive and effective disinfection systems.

Pseudomonas aeruginosa folliculitis is the most common recognizable infectious disease occurring after use of whirlpools and hot tubs. The factors that affect the host's susceptibility to whirlpool-related infection are the anatomic and physiologic defenses of normal skin, the microecology of the skin surface, factors intrinsic to the individual host, and behavioral factors. The structural components of the skin maintain an environment at the skin surface that makes human skin an inhospitable habitat for microflora. However, natural and experimental models of P. aeruginosa skin infection suggest that immersion in whirlpools may negate many of the body's normal host defenses, especially the very low humidity at the skin surface. Transient colonization of skin with P. aeruginosa may lead to elaboration of toxins in vivo, resulting in the characteristic dermatitis.

Pseudomonas aeruginosa is the most frequently isolated microorganism from whirlpool water and lesions associated with outbreaks of dermatitis and folliculitis related to whirlpool exposure. Strains were selected from 19 outbreaks of P. aeruginosa infections (1977 to 1983) associated with whirlpool use; they were examined to determine if the strains possessed unique virulence factors or characteristics that might aid in their selection in the environment.

P. aeruginosa, 011, was the predominant serotype isolated from whirlpool water as well as from bathers with dermatitis or folliculitis, followed by serotypes 09, 04, and 03. Antimicrobial susceptibility patterns were similar for all strains. Strains of P. aeruginosa from bathers and water demonstrated statistically significant differences in extracellular enzyme production compared with control strains. P. aeruginosa, serotypes 09 and 011, were found to be sensitive to low levels of chlorine. These data suggest that, if adequate levels of free available chlorine are maintained, P. aeruginosa should have little opportunity to persist in whirlpools.

A bather's risk of P. aeruginosa dermatitis or folliculitis appears to be affected primarily by three factors: 1) immersion in water colonized by P. aeruginosa, 2) skin hydration with altered skin flora, and 3) toxic reactions to extracellular enzyme or exotoxins produced by P. aeruginosa. Although a single virulence factor was not identified from the results of this study, there are some indications that the enzymes produced by these microorganisms play an important role in the pathogenesis of disease associated with whirlpool use.

A bacteriological study was completed on pools and whirlpools operated by hotels and private health clubs in the metropolitan area of Toronto, Ontario, Canada. Coliform bacteria, fecal coliform bacteria, and fecal streptococci were found only when other indices showed a drastic deterioration in water quality. Aerobic plate counts were higher, and staphylococci and Pseudomonas aeruginosa occurred more often in whirlpools than in swimming pools. There was a correlation between aerobic plate counts and the presence of staphylococci and P. aeruginosa. P. aeruginosa was rare in swimming pools in the absence of staphylococci; however, in whirlpools the organism was often found in the absence of staphylococci, and when aerobic plate counts were low. P. aeruginosa and plate counts in excess of 3,000 per ml occurred more frequently in whirlpools when the free chlorine residual was less than one part per million. The surface film showed concentrations of staphylococci far greater than the pool water. Whirlpools appear to present a different ecosystem that favors the establishment of P. aeruginosa. Staphylococci, but not Staphylococcus aureus, are useful in indicators of pool water quality but better laboratory methodology is required. Additional attention should be directed to the bacteriology of the water surface film, which presents a more direct hazard to bathers.

High temperature bathing in hot tubs, spas and whirlpools poses four potential public health concerns: injury/death, disease transmission, possible teratogenic effects, and congestive heart failure or dysrhythmias for individuals with cardiac problems. Health departments need criteria before initiating environmental and epidemiologic investigations. These criteria must include severity of the disease and number of individuals possibly exposed. In addition, public health officials are obligated to define the magnitude of the problem, inform affected individuals and institute appropriate control measures. Optional information should be collected during an environmental and epidemiologic investigation to clarify the mechanisms of disease transmission and design control measures. The public health response to improving hot water bathing safety and sanitation should be directed at primary prevention. Educational efforts would be directed toward whirlpool operators, users and the medical community. Included should be a review of regulations addressing the construction and operation of public spas and whirlpools.

The Acquired Immune Deficiency Syndrome (AIDS) continues to perplex health care providers. As our knowledge has increased, so has the number of questions, especially those related to infection control and employee health. Since the last time AIDS was reviewed in this column, additional information has become available which elaborates on some of the infection control aspects of this disease.

The human T-cell lymphotropic retrovirus (HTLV-III) appears to be the cause of AIDS. Other names used for HTLV-III are lymphadenopathy-associated virus (LAV) and AIDS-associated retrovirus. So called co-factors may be necessary to initiate disease after an individual acquires HTLV-III infection. Agents such as cytomegalovirus, the Epstein-Barr virus and multiple exposures to HTLV-III have been suggested as possible cofactors. Only a relatively small percentage of individuals who acquire HTLV-III antibody eventually develop overt disease or “full-blown AIDS.” Studies to date have shown that after 1 to 5 years of follow-up, 4% to 19% of seropositives developed AIDS.

In addition, the spectrum of disease caused by HTLV-III appears to be broader than originally thought. An additional 25% of those with antibody may have developed AIDS-related diseases including neurological symptoms, fever, weight loss, diarrhea, oral candidiasis and lymphadenopathy during the follow-up period.

Prospective payment fever is an all pervasive affliction that will spare no segment of the health care field. The implied rigidity of these regulations will probably not accommodate arguments that infection control efforts are cost-effective in the long run. It shall force all who labor in this field to exercise judicious restraint in the use of institutional resources. Microbiological analyses provide the most factual information lor infection control efforts. However, recent graduates of medical and nursing schools are the victims of the de-emphasis of bread-and-butter microbiology in their curricula. They lack the ability to request only clinically relevant examinations and do not appreciate the implications of microbiological results with respect to the patient and the health of the hospital or the community at large.

Cost-effective ordering of microbiological and related patient examinations must, therefore, be based on an educational effort that indoctrinates responsible personnel in the appropriateness of requests based on clinical judgment and laboratory instructions. The DRG-induced change in the basic philosophy of patient care demands that microbiologists must become involved in the clinical use of the information they generate, ie, in the relevance of laboratory data to the care of patients. This interaction must benefit the laboratory scientist, for he or she can now insist that important patient information accompany each specimen.