Legionnaires’ disease: A critical report of the pneumonia of unknown origin outbreak in Argentina

An outbreak of pneumonia of unknown origin was identified in a health facility in Tucumán, Argentina in August 2022. Initial laboratory testing has suggested Legionella pneumophila and Legionella spp. as the causative agent of this pneumonia cluster. However, confirmation of these early results is ongoing and requires identification of the bacteria in environmental samples, matching of environmental samples to patient samples and wider testing of those affected by the outbreak. Official identification of a Legionnaires’ disease outbreak faces many challenges including limited diagnostic capabilities in local laboratories, reduced sensitivity of available tests and inadequate clinical samples. In the absence of official identification of the source of the outbreak, other differential diagnoses for pneumonia should not be overlooked as this may result in missed cases and inadequate control measures being implemented.