Epidemic Legionellosis in England and Wales 1979–1982

Do contaminated dental unit waterlines pose a risk of infection?

“…A nation-wide survey performed by the Legionella Reference Laboratory, CPHL in the England and Wales measuring risk factors in notified cases of Legionnaires' disease, failed to find any direct association with prior dental treatment. 61 Even allowing for underreporting of mild cases of Pontiac fever or clinical misdiagnosis of the cause of pneumonia, the risk is vanishingly small. This may be explained by the combination of low prevalence rate and bacterial load of Legionella spp.…”

WidespreadLegionella pneumophilacontamination of dental stations in a dental school without apparent human infection

“…National surveillance data (Bartlett & Bibby, 1983) on legionellosis from 1979 was reviewed to see whether reported cases had worked as dentists or in a dentalcare-related occupation. Data was also reviewed for cases who had a history of dental treatment in the 2 weeks before the onset of symptoms: this information was sought in 1984-5.…”

Potable water as a source for legionellosis.

“…Most outbreaks of other waterborne infections are traced to inadequately maintained water supplies, exogenous contamination of which causes infection because of inadequacies in water treatment. Legionellosis outbreaks on the contrary have most commonly been observed in hospitals and hotels fed by well-maintained municipal water supplies, although exceptions have been noted in which clusters occurred in buildings that receive untreated water (3,4). In searching for an explanation for the striking differences between legionellosis and other waterborne infections, in these regards it may be important to consider that Legionellae may not be acquired in most cases by ingestion and that the epidemiology of organisms adapted to warm water may be very different from that of organisms more usually associated with cold water.…”