[Generally accepted engineering standards and Legionella in drinking water : findings from Frankfurt am Main]

Can mandatory monitoring in rental apartments effectively prevent legionellosis? A retrospective analysis of data from Regensburg with a review of the literature

Background:Legionella pneumophila can cause severe, often fatal, pneumonia in humans. Mandatory water sampling in commercially used buildings (mainly rental apartments) as regulated in the Drinking Water Ordinance (Trinkwasserverordnung) aim to protect the population against infection with Legionella. However, no data exist to date that could prove the effectiveness of the measures. At the same time, having the Public Health Department’s Infection Control Division deal with Legionalla is very time consuming.

Methods: A retrospective analysis of data from the city and district of Regensburg, a selective literature search, a prospective survey of workload using an anonymous questionnaire were performed.

Results: The evaluated data from the city/district of Regensburg suggest underreporting to a similar extent as shown by the RKI’s data in the compared period. Neither is the actual incidence known, nor can exposures be clearly determined in most cases. The exposure categories “travel” and “private/occupational” seem to be the most pertinent.

The potential public hazard of Legionella posed by domestic plumbing systems is unclear. A connection between exceeding the technical measurement limit (Technischer Maßnahmenwert, TMW) in routine tests in rental apartments and disease cases cannot be shown. A survey among non-medical personnel in the field of infection control and hygiene on the time spent on the topic of Legionella yielded a mean number of 39% of daily working hours for the observed 2-month period.

Conclusion: The data on incidence, exposure, and causality are incomplete. Evidence of effective protection by the current practice of sampling in apartment buildings could not be found. For many aspects, there are no unambiguous data in the literature. Restricting mandatory monitoring to certain public/commercial institutions should be discussed, given the high workload for the Public Health Department and the unproven protective effect. Further research on this topic is necessary.