COMMITTEE: Infectious Disease

TITLE: Cryptosporidium Contamination of Finished Water from Public Water Supplies

ISSUE: The Environmental Protection Agency (EPA) mandated testing of public water supplies for Cryptosporidium will lead to frequent occurrences where oocysts will be found in finished waters. Public health agencies, water utilities, regulators of water supplies, and local governments will need to respond to these findings. Unfortunately, there is little known regarding the level of Cryptosporidium oocysts that can be demonstrated in finished drinking water that constitutes an increased risk to the public's health.

POSITION TO BE ADOPTED: CSTE recommends that the Centers for Disease Control (CDC) convene a national meeting regarding Cryptosporidium contamination of public water supplies prior to July 30, 1994. The objective of this meeting shall be to develop plans for immediate, and long-term public health practice, policy and research regarding Cryptosporidium contamination of public water supplies with the ultimate development of a consensus document on this topic.

Key participants in this national meeting include representatives of CSTE, CDC, Association of State and Territorial Health Officials (ASTHO), Association of State and Territorial Public Health Laboratory Directories (ASTPHLD), National Association of State Public Health Veterinarians (NASPHV) local public health agencies (e.g. Milwaukee, New York City); state environmental health officials; state environmental protection agency officials; National Association of County Health Officials (NACHO); EPA; state and local water utilities; the Association of State Drinking Water Administrators; the American Water Works Association; U.S. Conference of Mayors; federal, state, and local elected officials; representatives of immunocompromised populations, and representatives of other appropriate nongovernmental agencies.

BACKGROUND AND JUSTIFICATION: Specific issues to be addressed at the meeting include:

1) Guidelines for governmental response to the finding of Cryptosporidium oocysts or increased turbidity in finished (treated) water. These should include: 

a) Recommendations regarding water sampling test results that should lead to issuing boil water orders.
b) Clarification of roles and coordination of agencies responsible for issuing boil water orders - e.g., water utilities, public health authorities, etc.
c) Recommendations regarding tests or circumstances that are required for lifting boil water orders. 

d) Provision of EPA/CDC technical assistance to state and local health departments for water testing and public health surveillance in response to "abnormal" findings in finished water.

2) Definition of the efforts needed to understand the public health significance of finding Cryptosporidium oocysts and elevated turbidity in finished water.

3) Definition of the role of public health surveillance for Cryptosporidium infection and actions required to address inadequate testing of diarrheal stools for Cryptosporidium by providers and clinical laboratories.

4) Decisions regarding public health messages that should be provided to immunocompromised persons regarding the use of public water supplies that have surface water sources (e.g. advisability of point-of-use water filters or bottled water).

5) The need for boil water advisories to those persons who are immunocompromised and who consume water with low levels of Cryptosporidium and increased turbidity in finished drinking water.


Agencies for response: U.S. Department of Health and Human Services

Agencies for information: ASTHO
Local public health agencies 
State environmental health officials 
State environmental protection agency officials; 
State and local water utilities
Association of State Drinking Water Administrators 
American Water Works Association 
U.S. Conference of Mayors 
Federal, state, and local elected officials 

CONTACT: Michael T. Osterholm, PhD, MPH
State Epidemiologist 
Chief, Acute Disease Epidemiology Section 
Minnesota Department of Health
717 Delaware Street, SE, PO Box 9441
Minneapolis, MN 55440-9441
Phone: (612) 623-5414 Fax: (612) 623-5743