The typical presentation of an atypical pathogen during an outbreak of Legionnaires' disease in Vila Franca de Xira, Portugal, 2014

Legionella and SARS-CoV-2 Coinfection in a Patient With Pneumonia - An Outbreak in Northern Portugal

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has plagued virtually every continent and country, and Portugal is no exception. The high number of cases has caused a major burden on health services and obvious economic consequences, forcing an important reformulation in the health sectors' organization. In the past weeks, counties in the country's northern coastal region have reported an increasing number of Legionella cases, whose origin is yet to be determined. This exacerbates the already important pressure on the region's health facilities. We present a case of a patient diagnosed with Legionella pneumonia and concomitant coronavirus disease 2019 (COVID-19) pneumonia, highlighting the need for etiological investigation not only for common community agents but also for pandemic pathogens and regional outbreaks.

The unprecedented 2014 Legionnaires' disease outbreak in Portugal: atmospheric driving mechanisms

A large outbreak of Legionnaires' disease occurred in November 2014 nearby Lisbon, Portugal. This epidemic infected 377 individuals by the Legionella pneumophila bacteria, resulting in 14 deaths. The primary source of transmission was contaminated aerosolized water which, when inhaled, lead to atypical pneumonia. The unseasonably warm temperatures during October 2014 may have played a role in the proliferation of Legionella species in cooling tower systems. The episode was further exacerbated by high relative humidity and a thermal inversion which limited the bacterial dispersion. Here, we analyze if the Legionella outbreak event occurred during a situation of extreme potential recirculation and/or stagnation characteristics. In order to achieve this goal, the Allwine and Whiteman approach was applied for a hindcast simulation covering the affected area during a near 20-year long period (1989-2007) and then for an independent period covering the 2014 event (15 October to 13 November 2014). The results regarding the average daily critical transport indices for the 1989-2007 period clearly indicate that the airshed is prone to stagnation as these events have a dominant presence through most of the study period (42%), relatively to the occurrence of recirculation (18%) and ventilation (17%) events. However, the year of 2014 represents an exceptional year when compared to the 1989-2007 period, with 53 and 33% of the days being classified as under stagnation and recirculation conditions, respectively.