Waterborne Disease Outbreaks and the Multi-barrier Approach to Protecting Drinking Water - Global Drinking Water Management and Conservation - page 13

because of the vulnerability of surface water to potential contaminants in the sur-
rounding environment. Therefore, cryptosporidiosis occurs most commonly in
communities that rely on surface water and do not provide

filtration.
A well-documented outbreak of cryptosporidiosis occurred in Braun Station,
Texas in May July of 1984. The groundwater source was chlorinated, but was

believed to have been contaminated by sewage (Rose 1997 , p. 141). The outbreak
caused 2,000 cases of reported illness in the community of approximately 5,900
people. A lack of effective treatment was the system failure that caused this out-
break. Cryptosporidium is resistant to chlorine and the treatment facility did not
provide

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filtration, which would have been effective against the pathogen.
In January February of 1987 Carrollton Georgia experienced an outbreak of

cryptosporidiosis. The surface water source became contaminated and caused over
13,000 cases of illness. At the time of the outbreak approximately 27,000 people
were supplied by the water system in the county of 64,900 people. The source of
contamination is believed to have been fecal runoff from nearby grazing cattle and
sewage over

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ow from upstream into the river source (Solo-Gabriele and Neumeister
1996 , p. 79). Conventional treatment was used prior to the outbreak, which includes
coagulation,

flocculation, sedimentation, filtration, and chlorination. Improper

filtration process, allowed the contaminant to spread
through the distribution system (Rose 1997 , p. 141). This means that the system
failure in this outbreak is inadequate filtration. This is a failure in the treatment
process of the water system, and therefore could have been prevented by a properly
working system. Of course it could be also argued that there was inadequate mon-
itoring since the operators did not detect, and therefore did not

flocculation, which is part of the

fix the improperly

working flocculation. Following the outbreak, the treatment system was upgraded in

Carrollton with new

filter monitoring, improved chemical
dosage, and operational practices (Solo-Gabriele and Neumeister 1996 , p. 81). These
alterations are signi

flocculators, increased

cant improvements in an effort to prevent future contamination.

June of 1992, Jackson County Oregon also experienced an outbreak of
cryptosporidiosis. The contamination of the surface water sources caused 3,000 cases
of de

In January

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ned illness, but is estimated to have affected approximately 15,000 people. The
outbreak occurred within two water supplies of Jackson County. The water system of
the city of Medford supplied 70,000 people, and the city of Talent s system supplied

3,000 people (Solo-Gabriele and Neumeister 1996 , p. 79). The water in Medford
came from Big Butte Springs, and was treated with chlorine only. In Talent the water
came from a river source that was treated with

'

flocculation, sedimentation, filtration,

and chlorination. The source of contamination of Medford is springs is believed to

have been contaminated surface water and the source of Talent

'

s river contamination
is believed to have been treated wastewater that was received by the river. Drought
conditions at the time may have lessened its dilution in the river (Solo-Gabriele and
Neumeister 1996 , p. 80). Another suggested source for Talent is agricultural runoff
that possibly could have entered the river through runoff of rainfall. Again system
failures were involved in Medford

'

' s outbreak with a lack of filtration and a sole

reliance on chlorination, and also in Talent with poor filtration that did not take into

account increased in turbidity at the time (Rose 1997 , p. 141). Following the