Environmental Engineering Reference
In-Depth Information
contaminated groundwaters in the United States have been responsible for more
waterborne outbreaks than contaminated surface waters, and that during the
period 1971 to 2000, waterborne outbreaks have declined in untreated ground
waters, whereas disinfected groundwaters have accounted for 38 percent of
the groundwater-related waterborne outbreaks during that time frame.
16
Most
recently, however, a waterborne outbreak suspected to involve a
Salmonella
sp.
was believed to be linked to the undisinfected, deep-well, groundwater system
serving Alamosa County, Colorado, in the United States. On March 19, 2008,
at least 33 confirmed cases of salmonella infections were recorded, and the
Colorado Department of Health issued a “bottled water” advisory. The source
of the contamination was unknown, but a cross-connection with a wastewater
line or a violated storage water tank was suspected. The following day, the
number of confirmed and suspected salmonella cases rose to 79. Two days later,
139 people were reported ill from salmonella infections, and the city declared a
state of emergency. By Sunday, March 28, the suspected case load had reached
276, with 10 people hospitalized. Laboratory-confirmed-cases numbered 72
and a candidate pathogen,
Salmonella enterica
serotype Typhimurium, was
isolated from the stools of confirmed victims.
45
The “boil order” was lifted
on April 11, 2008 and Alamosa likely will be required to comply with U.S.
EPA Groundwater Disinfection Rule as published in the Federal Register on
November 8, 2006 concerning disinfection of groundwater public drinking
water supplies. It was reported on April 20, 2008 that 411 salmonella cases, of
which 112 were confirmed and 18 hospitalized, included one death not proven
responsible to infection by salmonella.
46
Waterborne outbreaks occur more frequently in noncommunity water systems
than in community water systems; however, the number of cases associated
with community water systems is usually larger than in noncommunity water
systems. In the period 1991 to 2000, the annual average of waterborne out-
breaks in noncommunity water systems was approximately eight compared to
six outbreaks for community water systems. The median number of illness
cases associated with the noncommunity and community outbreaks was 112 and
498, respectively.
16
Although waterborne diseases account for only a very small
percentage of all human illness in the United States and other industrialized
countries, this advantage can only be maintained by the continued reduction
in biological and chemical pollution of our surface and groundwaters and by
complete and competent treatment of drinking water. A case in point is the cryp-
tosporidiosis outbreak that occurred in Milwaukee, Wisconsin, in 1993, resulting
in an estimated 403,000 cases of watery diarrhea.
47
Although in excess of 100
deaths have been stated in various media sources, 54 deaths were
officially
reported in the 4-year post-outbreak period, of which 85 percent involved AIDS
patients;
48
testimony to the ravishing effect of infectious diseases on immuno-
compromised individuals. The magnitude of the Milwaukee incident is such that
it represented 93 percent of the total 173 waterborne disease outbreaks during the
period 1991 to 2000. The total cost of the Milwaukee outbreak was estimated
