Current Waterborne Disease Burden Data & Gaps

Much is known about the risk factors for waterborne illness, but the overall occurrence of waterborne illness in the U.S. is unknown. Regulatory and public health agencies and academic researchers have published estimates of the number of illnesses associated with U.S. drinking water systems and marine water venues. These waterborne disease burden estimates provide a foundation for future work to quantify all U.S. waterborne illness, but these current estimates do not include all types of waterborne disease nor waterborne disease from all possible types of water exposures and venues.

Pathogen-specific illness and cost estimates also provide important contributions to understanding the health impact of particular waterborne diseases. Many of these pathogens can also be spread in other ways in addition to water (for example, food, person-to-person). The total disease burden from each pathogen and the proportion due to waterborne transmission will both inform the comprehensive waterborne burden of disease estimate.

The following publications highlight what is currently known about the scope and burden of waterborne illness in the U.S:

Pathogen-specific Illness and Cost Estimates

Scope

  • Deaths 1, emergency department (ED) visits, and hospitalizations 2 associated with 13 diseases that can be transmitted by water
  • The 13 selected diseases have been implicated in waterborne disease outbreaks or are otherwise known to be transmitted by water:
    • Acute otitis externa, campylobacteriosis, cryptosporidiosis, Escherichia coli (E. coli) infection, free-living ameba infection, giardiasis, hepatitis A virus (HAV) infection, Legionnaires’ disease, nontuberculous mycobacterial (NTM) infection, Pseudomonas-related pneumonia or septicemia, salmonellosis, shigellosis, and vibriosis or cholera
  • Most of the diseases studied can also be transmitted through other routes, such as contaminated food or having contact with a sick person.

Estimates

  • 6,939 annual total deaths were documented for 13 diseases caused by pathogens that can be transmitted by water 1
    • Of the 6,939 deaths, 91% were associated with three environmental pathogens that can grow in water system biofilms: Legionella (Legionnaires' disease) (250 deaths), NTM (1,216 deaths), and Pseudomonas-related pneumonia (1,618 deaths) or septicemia (3,217 deaths) 1
    • Of the 6,939 deaths, 7% were associated with seven pathogens transmitted by the fecal–oral route: Campylobacter, Cryptosporidium, E. coli, Giardia, Hepatitis A, Salmonella non-typhoidal, and Shigella 1
  • 477,000 annual ED visits were documented for 13 diseases caused by pathogens that can be transmitted by water 2
    • 101,000 (21%) of the ED visits resulted in immediate hospital admission; the remaining 376,000 annual treat-and-release ED visits resulted in $194 million in annual direct costs 2.
    • Most treat-and-release ED visits (97%) and costs ($178 million/year) were associated with acute otitis externa (swimmer’s ear); this condition had the lowest mean cost per visit ($487/visit) 2.
    • Overall, the annual hospitalization and treat-and-release ED visit costs associated with the selected diseases totaled to $3.8 billion 2.

What is not included in the scope of these 2017 pathogen-specific illness and cost estimates?

  • Estimates do not include all pathogens that could potentially be spread via water 1,2.
  • Estimates do not include the percentage of each illness attributable to waterborne transmission 1,2.
  • Estimates do not include less severe illness (i.e., illnesses that did not result in death 1 or a visit to the emergency department 2)
References
  1. Gargano JW, Adam EA, Collier SA, Fullerton KE, Feinman SJ, Beach MJ. Mortality from selected diseases that can be transmitted by water — United States, 2003–2009.External J Water Health. 2017;15(3):438-50.
  2. Adam EA, Collier SA, Fullerton KE, Gargano JW, Beach MJ. Prevalence and direct costs of emergency department visits and hospitalizations for 13 selected diseases that can be transmitted by water, United StatesExternal. J Water Health. 2017;wh2017083.

Scope

  • Hospitalization and outpatient healthcare costs associated with 10 primarily and partially waterborne pathogens 1
  • Gastroenteritis deaths associated with norovirus and Clostridium difficile 2

Estimates

  • Diseases (giardiasis, cryptosporidiosis, Legionnaires’ disease, otitis externa, and non-tuberculous mycobacterial infection) caused by primarily waterborne pathogens were associated with more than 40,000 hospitalizations, costing $970 million per year 1.
  • Diseases (campylobacteriosis, salmonellosis, shigellosis, HUS, toxoplasmosis) caused by partially waterborne pathogens were associated with 50,000 hospitalizations, costing $860 million per year 1.
  • Approximately 800 deaths are associated with norovirus each year 2.
  • Approximately 7,900 deaths are associated with Clostridium difficile each year 2.

What is not included in the scope of this 2012 pathogen-specific illness and cost estimate?

  • Estimates do not include all pathogens that could potentially be spread via water 1.
  • Estimates do not include the percentage of each illness attributable to waterborne transmission 1.
  • Estimates do not include the percentage of each illness attributable to waterborne transmission 2.
  • Estimates do not include less severe illness (illnesses that did not result in death) 2.
References
  1. Collier SA, Stockman LJ, Hicks LA, Garrison LE, Zhou FJ, Beach MJ. Direct healthcare costs of selected diseases primarily or partially transmitted by water.External Epidemiol Infect. 2012;140(11):2003-13.
  2. Hall AJ, Curns AT, McDonald LC, Parashar UD, Lopman BA. The roles of Clostridium difficile and norovirus among gastroenteritis-associated deaths in the United States, 1999-2007.External Clin Infect Dis. 2012;55(2):216-23.

Scope

  • National number of hospitalizations associated with pulmonary nontuberculous mycobacteria (NTM) diagnosis during 1998-2005
  • Demographic characteristics of hospitalized patients and trends over time

Estimate

  • 23,213 pulmonary NTM hospitalizations occurred during 1998-2005.
    • Seven out of 10 of these NTM hospitalizations (71%) occurred in patients without HIV/AIDS.
    • Over half of these NTM hospitalizations (57%) were among women.
    • Over half of these NTM hospitalizations (55%) were among patients who were over 70 years old.

What is not included in the scope of this 2009 pathogen-specific illness estimate?

  • Estimate does not include the percentage of illness attributable to waterborne transmission.
  • Estimate does not include pulmonary-NTM illness that did not result in hospitalization.
  • Estimate does not include NTM illness affecting other body systems (for example, skin or disseminated nontuberculous mycobacterial infection.)

Reference

Scope

  • National incidence of community-acquired pneumonia (CAP) hospitalizations
  • Legionella-specific estimate of annual number of CAP cases requiring hospitalization

Estimate

  • 8,000-18,000 cases of Legionella cause CAP hospitalizations each year

What is not included in the scope of this 1997 pathogen-specific illness estimate?

  • Estimate does not include the percentage of illness attributable to waterborne transmission.
  • Estimate does not include Legionella illness that did not result in hospitalization.
Reference

Current Waterborne Disease Burden Estimates

Scope

  • Cost of illness due to sea food consumption and contact with marine pathogens
  • Pathogen-specific cost estimates also included

Estimates

  • 5 million excess cases of gastrointestinal illness each year due to marine beach exposure, costing $300 million each year in healthcare expenses
  • In pathogen-specific analyses, researchers estimated that direct exposure to Vibrio species (V. vulnificus, V. parahaemolyticus, V. alginolyticus and K. brevis) costs approximately $30 million each year in healthcare costs

What is not included in the scope of the 2011 marine water burden estimates?

  • Estimates do not include waterborne illness from non-marine recreational water sources including freshwater beaches and rivers, lakes, and streams.
  • Estimates do not include recreational waterborne illness from chlorinated venues including pools, splash parks, spas, and hot tubs.
Reference

Scope

Estimate

Estimate break-down by type of public drinking water systems

  • 5.4 million cases of waterborne illness due to contaminated community groundwater (from wells serving 25 or more year-round residents)
  • 1.1 million cases of waterborne illness due to contaminated non-community groundwater systems (from wells serving at least 25 of the same people for at least 6 months, but not year-round)
  • 13 million cases of waterborne illness due to contaminated municipal source water systems (public drinking water distributed by the water utility).

For more information, see Public Water Systems.

What is not included in the scope of the 2008 drinking water burden estimates?

Reference

Scope

  • Burden of acute gastrointestinal illness (AGI) from public drinking water systems

Estimate

  • A range of 4.26–11.69 million AGI cases each year 1
  • A mean of 16.4 million AGI cases (range of 5.47–32.80 million cases) each year 2

What is not included in the scope of the 2006 drinking water burden estimates?

  • Estimates do not include waterborne illness from drinking water in private wells, small water systems, building water systems, or premise plumbing.
  • Estimates do not include waterborne illness from non-drinking water sources including recreational water venues or water systems for alternative uses including industry, agriculture, and medical uses.
  • Estimates do not include respiratory or other non-diarrheal waterborne illness.
References
  1. Colford JM, Roy S, Beach MJ, Hightower A, Shaw SE, Wade TJ. A review of household drinking water intervention trials and an approach to the estimation of endemic waterborne gastroenteritis in the United States.External J Water Health. 2006;4(Suppl 2):71-88.
  2. Messner M, Shaw S, Regli S, Rotert K, Blank V, Soller J. An approach for developing a national estimate of waterborne disease due to drinking water and a national estimate model application.External J Water Health. 2006;4(Suppl 2):201-40.