A community-based outbreak of severe respiratory illness caused by human adenovirus serotype 14

Background. Human adenoviruses (Ads) typically cause mild illnesses in otherwise healthy hosts. We investigated a community-based outbreak that had substantial morbidity caused primarily by Ad14, an uncommon serotype. Methods. We retrospectively reviewed the medical records of all patients with confirmed cases of Ad infection from 1 November 2006 through 31 July 2007 in Oregon. Isolates were typed by sequencing. We analyzed clinical and laboratory variables to identify risk factors for severe Ad14 disease. Results. Ad14 first emerged in Oregon in 2005. Of 67 cases of Ad infection detected during the study period, 40 (60%) involved Ad14. Most of the 38 Ad14-infected patients who had medical records available for review presented with fever and cough; 29 (76%) required hospitalization, 23 (61%) required supplemental oxygen, 18 (47%) required critical care, 9 (24%) required vasopressors, and 7 (18%) died. Lobar infiltrates on chest radiographs suggestive of bacterial pneumonia were common among those needing hospitalization. Older age, chronic underlying condition, low absolute lymphocyte counts, and elevated creatinine levels were associated with severe illness. Except for 1 case of possible hospital transmission, we identified no epidemiological links among patients. Conclusion. Ad14 emerged in Oregon in 2005 and became the predominant circulating type by 2007. Infection with this uncommon virus was primarily associated with a community-acquired pneumonia syndrome and caused substantial morbidity and mortality.