Healthcare-associated Legionnaires' disease: Limitations of surveillance definitions and importance of epidemiologic investigation.

Healthcare-associated Legionnaires' disease (HCA LD) causes significant morbidity and mortality, with varying guidance on prevention. We describe the evaluation of a case of possible HCA LD and note the pitfalls of relying solely on an epidemiologic definition for association of a case with a facility. Our detailed investigation led to the identification of a new serogroup 1 sequence type, confirmed a healthcare association and helped build the framework for our ongoing preventive efforts.