Legionella Routine Testing
The Centers for Disease Control and Prevention (CDC) does not recommend routine environmental water testing for legionella. CDC's mission is to save lives and protect people from health threats such as Legionnaires' disease (legionellosis). ASHRAE also avoids routine testing in their 188 standard, although it is mentioned in a normative appendix. But, CDC does recommend testing when there are 2 or more legionellosis cases associated with a specific time and place. CDC may be called in to assist state health departments with legionella testing to determine the environmental source of the legionella bacteria causing legionellosis cases.
Many building owners are routinely testing cooling towers and other water-containing mechanical equipment to determine whether their legionella control programs are working. They send water samples to labs that use a monoclonal antibody modification of the original CDC direct fluorescent antibody (DFA) test method or they send samples to labs that use the culture test method. The Wisconsin State Laboratory of Hygiene has a voluntary registration process (Elite) for labs that use the CDC-specified culture method. Some researchers believe that CDC's stand against routine environmental water testing is not appropriate.
Some Wisconsin State Laboratory of Hygiene Elite labs have been reporting excessive numbers of legionella to their clients with the recommendation that costly emergency legionella decontamination procedures begin immediately. Sometimes these lab's culture results were erroneous.
The scientific community needs to get more involved in outcome research to determine whether routine legionella testing of cooling towers and other water-containing equipment is a useful supplement to the guidelines published by ASHRAE, AIHA, AWT, EPA, CDC and OSHA. It is clear that the legionella testing regulations in the United Kingdom and the State of New York have not prevented legionellosis outbreaks. The State of New York ELAP certification program is for legionella testing of potable and non-potable water systems in residential health care facilities and hospitals. ELAP is only certifying for Legionella culture analysis. Certification for PCR and other methods (such as direct florescent monoclonal antibody testing) used for the identification and/or speciation of Legionella is not required.