New Report on Waterborne Illness Highlights Need for Public Health Protection
By Kelly A. Reynolds, MSPH, PhD
The US Centers for Disease Control and Prevention released a new report in the Emerging Infectious Diseases (EID) journal on the health and cost burden of waterborne disease in the United States.1 Information from the CDC supports that despite many advances in drinking water treatment, a substantial number of illnesses, hospitalization and deaths occur each year from waterborne routes.
Waterborne disease burden
Although others have previously estimated the burden of waterborne disease2, the recent EID publication represents the first time the CDC has collectively evaluated a disease burden from all water sources (drinking, recreational, environmental) and exposure routes (ingestion, contact, inhalation). Considering all these variables, they estimate up to 12 million waterborne illnesses annually resulting in up to 866,000 emergency department visits, 150,000 hospitalizations and 8,870 deaths. In the CDC study, the most prevalent diseases attributed to any waterborne source were ear infections (4.67 million average number of cases); norovirus (1.33 million cases); giardiasis (415 thousand cases); cryptosporidiosis (322 thousand cases). The latter three organisms are associated primarily with symptoms of stomach illnesses, including vomiting and/or diarrhea.
The causative agents of waterborne disease relative to public drinking water systems has shifted from large-scale epidemics like cholera and typhoid in the early 1900s due to a lack of treatment, to more endemic disease levels associated with treatment failures or aging infrastructure. Today, advanced water treatment, monitoring and regulation have resulted in a high-quality supply; however, broad-scale distribution and long-term storage needs create new challenges. According to the CDC report, there are six million miles of plumbing inside US buildings where water is subject to variable use patterns and may sit for long periods of time, becoming stagnant and growing biofilm. Control of water quality in onsite, premise plumbing systems has proven difficult. Recent and numerous Legionella outbreaks provide evidence of such risks. Legionnaires’ disease, caused by the Legionella bacterium, resulted in an estimated average of 995 deaths, second to nontuberculous mycobacteria (NTM) (3,800 deaths). Also in the top three causative agents of deaths attributed to waterborne transmission includes Pseudomonas (730 deaths). Infections from these organisms primarily result in respiratory illness.
The number of deaths from waterborne respiratory pathogens was an estimated 5,530 compared to enteric, or stomach/intestinal, pathogens that caused an estimated 131 deaths. Strategies for control of respiratory versus enteric pathogens may be different based on the nature of the increased growth potentials for respiratory pathogens in premise plumbing.
Relating illnesses to costs
Direct healthcare costs for hospitalizations and emergency department visits are estimated at an average of $3.33 billion (USD) and up to $8.77 billion each year. These costs were derived from private, Medicare and Medicaid insurance rates combined with out-of-pocket expenses. Estimated costs could be significantly increased if the magnitude of both minor illness, not resulting in hospital visits but nonetheless impacting quality of life and productivity, and severe outcomes, such as death, were considered. Another study used predictive estimates of nine million cases of acute illness, 600 thousand long-term chronic health effects and 1,400 deaths attributed to drinking waterborne microbes. This study found that the cost of illness far outweighed the cost of having and maintaining a POU device and that household POU systems, on average, were cost-beneficial in US applications.3 In addition, greater cost benefits of POU devices are expected in areas with increased pathogen exposure potentials.
As stated above, the majority of hospitalizations and deaths were caused by waterborne pathogens that are commonly associated with biofilms, including NTM, Pseudomonas, and Legionella. These three pathogens alone shared an annual cost burden of $2.39 billion in the US, compared to a cost burden of $160 million from enteric diseases. According to the CDC report, septicemia caused by Pseudomonas resulted in the highest per hospital-stay cost at an average of $38,000. Costs were highly variable across this category of illness and treatment, ranging from a low of $6,340 to a high of $172,000. Similarly, costs for Legionella infections averaged $37,000 per event, with a range of $7,950 to $149,000.
The CDC estimates were limited in that they only considered 17 microbial agents (Table 1) that represented the most common illnesses and where data supporting waterborne transmission and quantifiable health outcomes were available. Case numbers may be higher if more pathogens are included, but an attempt was made to adjust for known errors due to under-reporting and under-diagnosing of waterborne illnesses. For most drinking water-transmitted pathogens, however, no multipliers were applied for under-reporting (See Collier et al. 2021; Appendix 1). Also missing was consideration of adverse health effects associated with chemicals or algal toxins in drinking water supplies.
Another study used a quantitative risk assessment approach to estimate potential health outcomes based on results from treated water quality monitoring studies and predicted exposures. This study resulted in an estimated 19.5 million illnesses per year in the US due to drinking water exposures alone.2 Data used in this risk assessment was published in the early 2000s and before broad implementation of the US EPA groundwater disinfection rule but also did not include respiratory pathogen exposures, which we now know are major risk drivers.
Although there are a variety of published studies predicting different ranges of disease rates and costs associated with drinking water pathogens, the most recent CDC data indicates that at least one in 44 Americans gets sick from a waterborne infection from multiple sources (i.e., drinking and recreational water sources). From a regulatory perspective, target infection goals are less than one infection per 10,000 persons per year. Therefore, even with the advancements in treatment and monitoring, waterborne disease rates are at an unacceptable level. Given the potential for post-municipal treatment contamination in drinking water supplies, POU devices offer essential treatment options to control contamination at the tap for some of the most deadly and costly waterborne hazards.
- Collier S., et al. “Estimate of Burden and Direct Healthcare Cost of Infectious Waterborne Disease in the United States,” Emerging Infectious Diseases journal–CDC, p. 27(1), 2021.
- Reynolds, et al. “Risk of waterborne illness via drinking water in the United States,” Reviews in Environ Contamination and Toxicology, vol. 192, pp. 117-158, 2008.
- Verhougstraete, M.P., et al. “Cost-benefit analysis of point-of-use devices for health risks reduction from pathogens in drinking water,” Journal of Water & Health, vol. 18(6):968-982. 2020.
About the author
Dr. Kelly A. Reynolds is a University of Arizona Professor at the College of Public Health; Chair of Community, Environment and Policy; Program Director of Environmental Health Sciences and Director of Environment, Exposure Science and Risk Assessment Center (ESRAC). She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at firstname.lastname@example.org