Agriculture Reference
In-Depth Information
from lakes and rivers. They isolated salmonellae from only 8% of the water samples
and 46% of the sediment samples. Greater numbers of fecal coliforms,
Camplyobacter
,
and enteric viruses have also been detected in sediments than in the overlaying water
(Falabi and others 2002; Obiri-Danso and Jones 1999; Goyal and others 1977). The
accumulation of enteric pathogens can result in the rapid degradation of the quality
of the overlaying water by both man-made and storm events because of resuspension
of the sediment (Donovan and others 2008; Grimes 1980).
Survival in Water
Survival of waterborne pathogens in water is dependent on a number of factors:
Temperature—longer survival at lower temperatures. Viruses survive longest at
freezing temperatures.
Sunlight—longer survival in the dark. Ultraviolet light in sunlight plays the major
role in surface waters.
Particle matter—protects against effect of sunlight and antimicrobial factors in the
water.
Soluble organic matter — longer survival in the presence of sewage.
Temperature is usually the dominate factor in survival and can be used to approxi-
mate survival of an enteric pathogen in water. In surface waters the incidence of solar
radiation can also be used to predict the survival of indicator bacteria (Kadlec and
Knight 1996). Generally, enteric viruses survive the longest followed by protozoan
parasites and then bacteria. Table 7.1 lists reported survival time of
E. coli
O157:H7
Table 7.1.
Survival of
E. coli
O157:H7 in water
Study
° C
T
99
T
99.99
Comments
Czajkowska and others
2005
6
4 - 11
8 - 22
Surface waters from lakes and rivers
24
2 - 8
5 - 10
6
10 - 20
25 - 39
Sediments from the same lakes and rivers
24
5 - 8
10 - 30
Artz and Killham 2002
10
2
15
Groundwater used for drinking.
Conclusion:
copper in water inactivated
E. coli.
Avery and others 2004
10
1 - 6
ND
Raw sewage — 10 different samples
10
1 - 29
ND
Treated sewage
Ritchie and others 2003
15
20
> 90
Soil
15
35
58
Groundwater
McGee and others 2002
15
7.5
14.5
River water with feces (outdoors and lab)
Geldreich and others
(1992)
5
14 - > 35
ND
Filtered sterilized water samples from
Cobool, MO, after outbreak of
E. coli
O157:H7
Wang and Doyle (1998)
8
> 13
ND
Filtered tap water, unfi ltered lake water
23
9
ND
Filtered tap water
23
2 - 5
ND
Unfi ltered lake water
T
99
= time in days for a 99% decrease in titer.
T
99.99
= time in days for a 99.99% decrease in titer.
