Risk factors for contamination of domestic hot water systems by Legionellae

Journal Article · Thu Aug 01 04:00:00 EDT 1991 · Applied and Environmental Microbiology; (United States)

OSTI ID:5315763

Alary, M; Joly, J R ^[1]

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1. Univ. Laval, Quebec (Canada)

To assess risk factors associated with the contamination of the domestic environment by legionellae, 211 houses in the Quebec City area were randomly selected and water samples were collected from the hot water tank, the shower heads, and the most frequently used faucet. After centrifugation, concentrated samples were seeded in triplicate on BCYE and GPV media. Data on the characteristics of the hot water system and plumbing in the house and on the personal habils of the occupants were collected for each house. Among these 211 houses, hot water was provided by either an oil or gas heater in 33 and by an electric heater in 178. Legionellae were isolated from none of the samples from houses with oil or gas heaters and from 39% (69 of 178) of those with electric water heaters. This association remained highly significant after control for water temperature and other variables in a stratified analysis. In the 178 houses with an electric heater, 12% of the faucets, 15% of the shower heads, and 37% of the water heaters were contaminated. Legionella pneumophila serogroups 2 and 4 were the most frequently isolated strains. Logistic regression showed that factors associated with electric water heater contamination were (1) location of the house in older districts of the city (2) old age of the water heater, and (3) low water temperature. Contamination of the water heater was the only factor significantly associated with the contamination of peripheral outlets. This study shows that the presence of an electric heater is strongly associated with contamination of domestic hot water systems by Legionellae. The public health importance of this contamination is still unknown.

• OSTI ID: 5315763
• Journal Information: Applied and Environmental Microbiology; (United States), Journal Name: Applied and Environmental Microbiology; (United States) Vol. 57:8; ISSN 0099-2240; ISSN AEMID
• Country of Publication: United States
• Language: English

Related Subjects

552000* -- Public Health
99 GENERAL AND MISCELLANEOUS
APPLIANCES
BACTERIA
BUILDINGS
CANADA
COMPARATIVE EVALUATIONS
CONTAMINATION
DEVELOPED COUNTRIES
ELECTRIC APPLIANCES
EVALUATION
FUEL OILS
FUELS
GAS APPLIANCES
GROWTH
HEATERS
HOUSES
LEGIONELLA PNEUMOPHILA
LIQUID FUELS
MICROORGANISMS
NORTH AMERICA
OILS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PETROLEUM PRODUCTS
PUBLIC HEALTH
QUEBEC
RESIDENTIAL BUILDINGS
RISK ASSESSMENT
WATER HEATERS