Outbreak of adenovirus type 1 severe pneumonia in a French intensive care unit, September–October 2012

We herein describe and analyse the first outbreak of severe pneumonia caused by human adenovirus type 1 (HAdV C type 1), which included immunocompetent patients in an intensive care unit (ICU) of Marseille, France, and occurred between September and October 2012. Seven successive patients were diagnosed by HAdV specific real-time polymerase chain reaction with a positive bronchoalveolar lavage. After the collection of nasopharyngeal swabs from healthcare workers, three nurses working night shifts tested positive for HAdV C including one that had exhibited respiratory signs while working one week before the outbreak. She was the most likely source of the outbreak. Our findings suggest that HAdV-1 could be considered as a possible cause of severe pneumonia even in immunocompetent patients with a potential to cause outbreaks in ICUs. HAdV rapid identification and typing is needed to curtail the spread of this pathogen. Reinforcing hand hygiene with antiseptics with demonstrated activity against non-enveloped viruses and ensuring that HCWs with febrile respiratory symptoms avoid direct patient contact are critical measures to prevent transmission of HAdV in healthcare settings.