The Morbidity and Mortality Weekly Report (MMWR) is a weekly epidemiological digest for the United States published by the Centers for Disease Control and Prevention (CDC). It is considered by many practicing in the public health sector to be the primary publication for sharing public health information and recommendations that have been received by the CDC from state health departments.
On May 18, 2018 the CDC published “Outbreaks Associated with Treated Recreational Water – United States, 2000-2014. (MMWR May 18, 2018/67(19); 547-551). This report assimilated outbreak data associated with treated recreational water from public health officials from 46 states and Puerto Rico for the period of 2000 through 2014. The data documented 493 outbreaks resulting in 27,219 cases and eight deaths. Three hundred and sixty-three of the outbreaks were confirmed to be of infectious etiology. Fifty-eight percent of those (212) were caused by Cryptosporidium, which causes predominantly gastrointestinal illness. Sixteen percent (57) were caused by Legionella, which causes Legionnaires’ disease, a severe pneumonia, and Pontiac fever, a milder illness with flu-like symptoms. Lastly, 13 percent (47) of the outbreaks were caused by Pseudomonas, which causes folliculitis (hot tub rash) and otitis externa (swimmers’ ear). Investigations into the 363 confirmed infectious outbreaks identified a total of 24,453 individual cases of disease: 21,766 (89 percent) by Cryptosporidium, 940 (4 percent) by Pseudomonas and 624 (3 percent) by Legionella. Among the 8 deaths associated with the total number of outbreaks, Legionella was reported as responsible for at least six. Hotels were associated with 157 (32 percent) of the 493 total outbreaks and were considered the leading setting for these infections with 41 percent of the hotel-related outbreaks associated with hot tubs and spas. Approximately 20 percent of the 13,864 routine inspections of the public hot tubs and spas conducted in 16 jurisdictions in 2013 identified improper disinfectant concentrations. The temporal distribution for outbreaks was deemed bimodal: 56 percent of the outbreaks started between June and August and 9 percent at the beginning in March.
The CDC noted that these trends evidence mixed progress in preventing transmission of these three most common waterborne pathogens and underscores the utility of the CDC’s Model Aquatic Health Code (MAHC); www.cdc.gov/mahc. This model code stems from a CDC-sponsored national workshop called “Recreational Water Illness Prevention at Disinfected Swimming Venues”. First published on August 29, 2014 and now in its second edition, the MAHC’s stated mission is “to incorporate science and best practices into guidance on how state and local officials can transform a typical health department pool program into a data-driven, knowledge-based, risk reduction effort to prevent disease and injuries and promote healthy recreational water experiences.” The MAHC is not code but rather voluntary uniform guidelines provided to state and local agencies for the areas of design and construction, operation and maintenance, and policies and management of swimming pools, spas and other public disinfected aquatic facilities.
Outbreaks caused by waterborne pathogens continue to make news and attract attention from local and state health officials. When these infections cause serious injury and death, lawsuits often follow. Retrospective review of recreational water management plans and programs focus on existing codes, standards and guidelines for arguable breaches in the standard of care. Any owner, builder, designer or manager of a treated recreational water facility or a business that incorporates such a facility, would be well served to review all of the relevant water safety measures being implemented to determine if they are compliant with existing safety standards.