PROBLEM/CONDITION
Since 1971, CDC and the U.S. Environmental Protection Agency have maintained a collaborative surveillance system for collecting and periodically reporting data that relate to occurrences and causes of waterborne-disease outbreaks (WBDOs).
REPORTING PERIOD COVERED
This summary includes data for January 1995 through December 1996 and previously unreported outbreaks in 1994.
DESCRIPTION OF THE SYSTEM
The surveillance system includes data about outbreaks associated with drinking water and recreational water. State, territorial, and local public health departments are primarily responsible for detecting and investigating WBDOs and for voluntarily reporting them to CDC on a standard form.
RESULTS
For the period 1995-1996, 13 states reported a total of 22 outbreaks associated with drinking water. These outbreaks caused an estimated total of 2,567 persons to become ill. No deaths were reported. The microbe or chemical that caused the outbreak was identified for 14 (63.6%) of the 22 outbreaks. Giardia lamblia and Shigella sonnei each caused two (9.1%) of the 22 outbreaks; Escherichia coli O157:H7, Plesiomonas shigelloides, and a small round structured virus were implicated for one outbreak (4.5%) each. One of the two outbreaks of giardiasis involved the largest number of cases, with an estimated 1,449 ill persons. Seven outbreaks (31.8% of 22) of chemical poisoning, which involved a total of 90 persons, were reported. Copper and nitrite were associated with two outbreaks (9.1% of 22) each and sodium hydroxide, chlorine, and concentrated liquid soap with one outbreak (4.5%) each. Eleven (50.0%) of the 22 outbreaks were linked to well water, eight in noncommunity and three in community systems. Only three of the 10 outbreaks associated with community water systems were caused by problems at water treatment plants; the other seven resulted from problems in the water distribution systems and plumbing of individual facilities (e.g., a restaurant). Six of the seven outbreaks were associated with chemical contamination of the drinking water; the seventh outbreak was attributed to a small round structured virus. Four of the seven outbreaks occurred because of backflow or backsiphonage through a cross-connection, and two occurred because of high levels of copper that leached into water after the installation of new plumbing. For three of the four outbreaks caused by contamination from a cross-connection, an improperly installed vacuum breaker or a faulty backflow prevention device was identified; no protection against backsiphonage was found for the fourth outbreak. Thirty-seven outbreaks from 17 states were attributed to recreational water exposure and affected an estimated 9,129 persons, including 8,449 persons in two large outbreaks of cryptosporidiosis. Twenty-two (59.5%) of these 37 were outbreaks of gastroenteritis; nine (24.3%) were outbreaks of dermatitis; and six (16.2%) were single cases of primary amebic meningoencephalitis caused by Naegleria fowleri, all of which were fatal. The etiologic agent was identified for 33 (89.2%) of the 37 outbreaks. Six (27.3%) of the 22 outbreaks of gastroenteritis were caused by Cryptosporidium parvum and six (27.3%) by E. coli O157:H7. All of the latter were associated with unchlorinated water (i.e., in lakes) or inadequately chlorinated water (i.e., in a pool). Thirteen (59.1%) of these 22 outbreaks were associated with lake water, eight (36.4%) with swimming or wading pools, and one(4.5%) with a hot spring. Of the nine outbreaks of dermatitis, seven (77.8%) were outbreaks of Pseudomonas dermatitis associated with hot tubs, and two (22.2%) were lake-associated outbreaks of swimmer's itch caused by Schistosoma species.
INTERPRETATION
WBDOs caused by E. coli O157:H7 were reported more frequently than in previous years and were associated primarily with recreational lake water. This finding suggests the need for better monitoring of water quality and identification of sources of
[1]
B. A. Hegg,et al.
Self-Assessment Guide for Surface Water Treatment Plant Optimization
,
1997
.
[2]
Frederick W. Pontius,et al.
Implementing the 1996 SDWA Amendments
,
1997
.
[3]
G. Craun,et al.
Surveillance for waterborne-disease outbreaks--United States, 1993-1994.
,
1996,
MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries.
[4]
J. Rose,et al.
The infectivity of Cryptosporidium parvum in healthy volunteers.
,
1995,
The New England journal of medicine.
[5]
R. Glass,et al.
Detection and differentiation of antigenically distinct small round-structured viruses (Norwalk-like viruses) by reverse transcription-PCR and southern hybridization
,
1995,
Journal of clinical microbiology.
[6]
J. P. Davis,et al.
A massive outbreak in Milwaukee of cryptosporidium infection transmitted through the public water supply.
,
1994,
The New England journal of medicine.
[7]
Frederick W. Pontius,et al.
The current regulatory agenda: An update
,
1994
.
[8]
A K Highsmith,et al.
Surveillance for waterborne disease outbreaks--United States, 1991-1992.
,
1993,
MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries.
[9]
G. Craun,et al.
Waterborne-disease outbreaks, 1989-1990.
,
1991,
MMWR. CDC surveillance summaries : Morbidity and mortality weekly report. CDC surveillance summaries.
[10]
R. Calderon,et al.
Health effects of swimmers and nonpoint sources of contaminated water.
,
1991,
International journal of environmental health research.
[11]
G. Visvesvara,et al.
Epidemiology of free-living ameba infections.
,
1990,
The Journal of protozoology.
[12]
M. Levine,et al.
Inoculum size in shigellosis and implications for expected mode of transmission.
,
1989,
The Journal of infectious diseases.
[13]
A. Highsmith,et al.
Microbiology of recreational and therapeutic whirlpools
,
1988
.
[14]
N. E. Brown,et al.
A prospective study of swimming-related illness. I. Swimming-associated health risk.
,
1985,
American journal of public health.
[15]
D. Addiss,et al.
Cryptosporidium testing practices among clinical laboratories in the United States.
,
1996,
The Pediatric infectious disease journal.
[16]
L. Wilberschied.
A swimming-pool-associated outbreak of cryptosporidiosis.
,
1995,
Kansas medicine : the journal of the Kansas Medical Society.
[17]
R. Tauxe,et al.
The epidemiology of infections caused by Escherichia coli O157:H7, other enterohemorrhagic E. coli, and the associated hemolytic uremic syndrome.
,
1991,
Epidemiologic reviews.
[18]
Alfred P. Dufour,et al.
Health effects criteria for fresh recreational waters
,
1984
.