The 1993 Cryptosporidiosis outbreak in Milwaukee, Wisconsin was the largest waterborne disease outbreak in U.S. history. Over 400,000 people became ill after the parasite Cryptosporidium passed through the city's water treatment plant. At least 104 deaths were attributed to the outbreak, mostly among elderly and immunocompromised groups. The outbreak was caused by Cryptosporidium oocysts entering the Howard Avenue Water Purification Plant from upstream sewage discharge in Lake Michigan. Symptoms included stomach cramps, fever, diarrhea and dehydration. Extensive upgrades to water treatment systems have prevented any detections since, but Cryptosporidium remains a risk if untreated water is consumed.

1. Milwaukee Disaster-
PREPARED BY;
Sanjaya Regmi
MPH

2. Introduction
 The 1993 Milwaukee
Cryptosporidiosis
outbreak was a significant
distribution of
the Cryptosporidium protozoan
in Milwauke
Wisconsin, and the largest
waterborne disease outbreak
in documented United States
history.

3. Other major Cryptosporidiosis
outbreaks
 Cryptosporidiosis outbreaks
 Milwaukee,WI - 1993
 Carrolton,GA -1987
 Jackson County, OR - 1992 (small system)
 Cook County, MN - 1993 (small system)

4. severity
 Over the span of approximately two weeks,
403,000 of an estimated 1.61 million residents
in the Milwaukee area became ill.
 At least 104 deaths have been attributed to
this outbreak, mostly among the elderly
and immune compromised people, such
as AIDS patients.

5. Causes of Outbreak
 The Howard AvenueWater Purification Plant
was contaminated, and treated water
showed turbidity levels well above normal.
 It was one of two water treatment plants for
Milwaukee.
 The root cause of epidemic was never
officially identified; initially it was suspected
to be caused by the cattle genotype due to
runoff from pastures.

6. Location of the plant

7. Causes..
 It was also thought that melting ice and
snowmelt carrying Cryptosporidium may have
entered the water treatment plants through
Lake Michigan.
 Mackenzie et al. and the CDC showed that this
outbreak was caused
by Cryptosporidium oocysts that passed through
the filtration system of one of the city's water-
treatment plants, arising from a sewage
treatment plant's outlet 2 miles upstream in
Lake Michigan

8. Overall theories on why this
massive outbreak occurred ???
 a perfect storm
 South Plant intake grid location
 Unusual weather conditions
 Cross connection between sanitary and
storm sewer
 Change in water treatment coagulant
 Human amplification
 Limited testing prior to outbreak recognition

9. Symptoms
 Major Symptoms observed were;
 stomach cramps
 fever
 diarrhea and
 dehydration .

10. BURDEN Of the outbreak
The massive waterborne outbreak of cryptosporidiosis in 1993 in
Milwaukee caused illness in approximately 403,000 persons and
generated substantial healthcare costs and productivity losses.
It is estimated that on average, ill persons incurred
approximately $79 in medical costs and $160 in productivity
losses, resulting in $31.7 million in total medical costs and
$64.6 million in total lost productivity.
Applying these epidemiologic burden of illness estimates to
the average cost per case by severity, total medical costs and
productivity losses for the Milwaukee outbreak ranged from $75
to $118 million.

11. Cryptosporidium
 Cryptosporidium oocysts are common and
widespread in ambient water and can persist
for months in this environment.

12. cryptosporiridium
 The public health concern is worsened by the
resistance of Cryptosporidium to commonly
used water disinfection practices such as
chlorination. However, a well-operated water
filtration system is capable of removing at
least 99 of 100 Cryptosporidium oocysts in the
water.

13. Taxonomy of Cryptosporidium
 Cryptosporidium is one of several
protozoan genera in the phylum
Apicomplexa, which develop
within the gastrointestinal tract
of vertebrates throughout their
entire life cycles .
Apicomplexans are obligate
intracellular parasites.They are
characterized by the presence of
special organelles located at the
tips (apexes) of cells that
contain materials used to
penetratethe host cells and
establish successful infections

14. Oocyst of cryptosporiridium

15. Mature Cryptosporidium

16. lifecycle
Cryptosporidium has a complex life cycle, which
is completed in one to eight days and takes
place within the body of the host (either
humans or any of a wide variety of animal
species).
Cryptosporidium is excreted in the feces of an
infected host in the form of an oocyst.

17. lifecycle
 Cryptosporidium has a
complex life cycle, which
is completed in one to
eight days and takes
 place within the body of
the host (either humans
or any of a wide variety
of animal species).
 Cryptosporidium is
excreted in the feces of an
infected host in the form
of an oocyst.

19. Lifeycle..

20. pathogenesis
 Osmoticcharacterized by
enterocyte malfunction, eg:
 ↓ Na+ absorption
 ↑ Cl- secretion
 Inflammatory generally
associated with invasion of the
mucosa
 inflammation of the lamina
propria
 leukocytes in the stools
 Secretory generally
associated with bacterial
enterotoxins characterized by
watery diarrhea

21. Transmission
 Cryptosporidium can be transmitted from person
to person, or from farm livestock (e.g.,
cattle,sheep, or pigs) to humans, through the
fecal-oral route (Casemore, 1990).
 Ingestion of drinking water contaminated with
oocysts is the major mode of transmission.
 Other routes of transmission include fecal
contamination of fomites (i.e., inanimate objects
such as clothes, pens,doorknobs) and
contamination of recreational waters (e.g.,
swimming pools).

22. Present scenario
 Tests have not detected a
single Cryptosporidium cyst in filtered water
from the Howard Ave. plant since March 1999
 The parasite is still out there, lurking in
ponds, rivers and Lake Michigan.
 From 1994 through 1998, theWaterWorks
invested $89 million to upgrade the two
filtration plants and bolster barriers to
contamination of drinking water

23. Present scenario
 Today, the turbidity, or cloudiness, of filtered
water is measured constantly inside the
plants.
 Turbidity is an indicator of the concentration
of particles of all kinds suspended in water
 A filter would be shut down if any monitors
detect that turbidity or total particle counts
are rising to levels set as a precaution, though
well below regulatory standards.

26. Prevention
 Wash your hands
 Avoid swallowing recreational water
 Use caution when traveling
 Avoid drinking untreated water
 Adoption of improved disinfection
 Be careful when dealing with animals

27. Water can be made freed of crypto
by;
 Boiling water
 Using a filter that has been tested and rated
by National Safety Foundation
 Do not rely on chemical disinfection of Crypto
because it is highly resistant

29. Discussion...