Waterborne Disease Outbreaks


Cause: Many infectious agents including viruses, bacteria, and parasites. Common agents are norovirus, Giardia, and Cryptosporidium. Bacterial agents are less commonly implicated.

Illness and treatment: Symptoms and treatment vary with the agent.

Sources: Sources vary with the agent. Waterborne outbreaks can occur from ingestion of natural or recreational water, including pools, interactive fountains, and untreated drinking water.

Additional risks: Risks vary with the agent.

Prevention: Test private wells at least every 3 years and after potential contamination such as after floods. If ill with diarrhea do not enter recreational water, pools, or interactive fountains.

Recent Washington trends: Waterborne outbreaks are often difficult to detect. There are 0 to 3 outbreaks reported each year, each with 2 to dozens or even hundreds of cases.

Purpose of Reporting and Surveillance

  • To prevent tranmission from infected persons.
  • To identify and correct sources of exposure for waterborne disease (WBD) outbreaks.
  • To prevent further exposures to contaminated water and limit outbreaks.
  • To expand current understanding of the transmission, pathogenesis and community impact of illness caused by known WBD agents.
  • To identify new WBD agents, hazards or gaps in the water safety system.

Legal Reporting Requirements

  • Health care providers and Health care facilities: Outbreaks immediately notifiable to local health jurisdiction
  • Laboratories: No requirements for reporting WBD outbreaks; see disease-specific reporting requirements
  • Local health jurisdictions: Outbreaks immediately notifiable to the Washington State Department of Health (DOH) Communicable Disease Epidemiology (CDE)

Note: Individual confirmed or probable cases of specific conditions may have other specific reporting requirements; refer to disease-specific guidelines.