Background: In September 2008, an outbreak of pneumonia associated with an emerging human adenovirus (human adenovirus serotype 14 [HAdV-14]) occurred on a rural Southeast Alaska island. Nine patients required hospitalization, and 1 patient died.

Methods: To investigate the outbreak, pneumonia case patients were matched to control participants on the basis of age, sex, and community of residence. Participants in the investigation and their household contacts were interviewed, and serum samples and respiratory tract specimens were collected. Risk factors were evaluated by means of conditional logistic regression.

Results: Among 32 pneumonia case patients, 21 (65%) had confirmed or probable HAdV-14 infection. None of 32 matched control participants had evidence of HAdV-14 infection (P<.001 for the difference). Factors independently associated with pneumonia included contact with a known HAdV-14-infected case patient (odds ratio [OR], 18.3 [95% confidence interval {CI}, >or=2.0]), current smoking (OR, 6.7 [95% CI, >or=0.9]), and having neither traveled off the island nor attended a large public gathering (OR, 14.7 [95% CI, >or=2.0]). Fourteen (67%) of 21 HAdV-14-positive case patients belonged to a single network of people who socialized and often smoked together and infrequently traveled off the island. HAdV-14 infection occurred in 43% of case-patient household contacts, compared with 5% of control-participant household contacts (P = .005).

Conclusions: During a community outbreak in Alaska, HAdV-14 appeared to have spread mostly among close contacts and not widely in the community. Demographic characteristics and illness patterns among the case patients were similar to those observed in other recent outbreaks of HAdV-14 infection in the United States.