Graphic presentation and public health analysis of the 1993 Milwaukee Cryptosporidium Outbreak.

1. 1993 Milwaukee Cryptosporidiosis Outbreak
Jessica Baldwin
University of Wisconsin-Madison
Sociology 533: Public Health In Rural and Urban Communities
In 1993 a Cryptosporidiosis outbreak occurred in
Milwaukee, Wisconsin when the southern water
purification plant’s filtration system failed to
remove Cryptosporidium oocysts. The outbreak
mainly affected those serviced by Milwaukee’s
southern water treatment plant and had the
greatest negative health effects on immuno-
deficient and elderly populations (Griffin et al.).
•Affected 403,000 residents out of over 800,000
people the water treatment plant serviced (CDC).
•Responsible for about 100 deaths, mostly
amongst the elderly and immuno-compromised.
•More than 40,000 persons sought health care
•More than 4,000 were hospitalized
•Total lost productivity was estimated at 670,000
person-days (Griffin et al.).
Problem Statement Public Health Consequences
Milwaukee County Water Supply
Maximum Turbidity Levels
Figure 1: The Relative location of the Milwaukee Water Works North (X) and
South (Y) water treatment plants in 1993
Figure 2: North and South treatment plant approximate water intake location
in 1993
Figure 3: Maximum turbidity levels of treated water in the Northern and
Southern treatment plants from March 1 through April 28, 1993
The 1993 outbreak is the largest documented
waterborne disease outbreak in United States
history. Infectious diseases are a major cause of
morbidity and mortality worldwide (Eisenberg et
al.). The outbreak increased illness rates, hospital
and doctor visits, hospital stays, and the overall
health of the community. With better surveillance
and water treatment technology the outbreak
could have been prevented.
Significance
•Inadequate water quality standards
•Absence of properly functioning equipment
•Lack of surveillance over water treatment and
overall community health
•Use of backwashing to clean filters
•Poor turbidity surveillance
•A streaming-current monitor, which helps plant
operators adjust the dose of coagulant, had
been incorrectly installed in the southern station
•Monitors for continuous measurement of the
turbidity of filtered water were not functioning
(Mac Kenzie et al.).
Selected Causes
SURVEILLANCE
•Hire more workers to monitor equipment
function
•Assign workers to specifically test turbidity
levels
•Improve disease surveillance methods
•Require physicians to request routine stool
exams for cryptosporidium for patients displaying
symptoms, such as watery diarrhea (Mac Kenzie
et al.).
Suggested Interventions
INFRASTRUCTURE
•Spending on treatment infrastructure
1994-1998: Milwaukee Water Works invested
$89 Million; since 1998, ~$180 Million (Behm).
•Constant turbidity measurements inside the
plants
•Auto shut-down feature
Implemented Interventions
Behm, D. (2013). Milwaukee marks 20 years since cryptosporidium outbreak. Milwaukee
Wisconsin Journal Sentinel.
Betancourt, W. Q., & Rose, J. B. (2004). Drinking water treatment process for removal of
cryptosporidium and giardia. Veterinary Parasitology, 126, 219-34.
Corso et al. (2003). Cost of illness in the 1993 waterborne cryptosporidium outbreak, milwaukee,
Wisconsin. Centers for Disease Control and Prevention: Emerging Infectious
Diseases, 9(4), 426-431.
Davis, J. (2010, November 10). Case study: lessons from the massive waterborne outbreak of
cryptosporidium infections, Milwaukee, Wisconsin, 1993. Water Safety and Quality:
Issues Affecting Food Safety and Public Health. Lecture conducted from University of
Wisconsin-Madison Food Research Institute, Madison, WI.
Eisenberg et al. (2002). Disease transmission models for public health decision making:
Analysis of epidemic and endemic conditions caused by waterborne
pathogens. Environmental Health Perspective, 110(8), 783-90.
Mac Kenzie et al. (1994). Cryptosporidium infection from milwaukee's public water supply. New
England Journal of Medicine, 331(3), 161-67.
Proctor, M. E., Blair, K. A., & Davis , J. P. (1998). Surveillance data for waterborne illness
detection: An assessment following a massive waterborne outbreak of
cryptosporidium infection. Epidemiology Infection, 120, 43-54.
Sources Cited
Water Treatment Process
Figure 4: Overview of Milwaukee’s water treatment process