Emergence of community-acquired adenovirus type 55 as a cause of community-onset pneumonia

Abstract

Background: Since 2008, severe cases of emerging human adenovirus (HAdV) type 55 (HAdV-55) were reported sporadically in China. But no comparative studies had been conducted to discern the differences in epidemiologic and clinical abnormalities between HAdV-55 and other types (HAdV-7, HAdV-3, HAdV-14, HAdV-50, and HAdV-C).

Methods: A multicenter surveillance study for adult and adolescent community-acquired pneumonia (CAP) was conducted prospectively in Beijing and Yan Tai between November 2010 and April 2012. A standardized data form was used to record clinical information. The viral DNA extracted from the clinical samples or adenovirus viral isolates was sequenced.

Results: Among 969 cases, 48 (5%) were identified as adenovirus pneumonia. Six branches were clustered: HAdV-55 in 21, HAdV-7 in 11, HAdV-3 in nine, HAdV-14 in four, HAdV-50 in two, and HAdV-C in one. Most HAdV-55 cases were identified during February and March. All the hypervariable regions of the hexon genes of the 21 HAdV-55 strains were completely identical. Patients who had HAdV-55 were about 10 years older ( P = .027) and had higher pneumonia severity index scores ( P = .030) compared with those with other types (HAdV-7, HAdV-3, HAdV-14, HAdV-50, and HAdV-C). Systemic BP was also higher among patients in the HAdV-55 group ( P = .006). Unilateral or bilateral consolidations were the most common radiologic findings in both patients with HAdV-55 and those with other types (57.9% vs 36%). More than one-half of the patients were admitted to hospital; oxygen therapy was given to 29.2% of the 48 patients, and two needed mechanical ventilation.

Conclusions: HAdV-55 has established itself as a major pneumonia pathogen in the Chinese population, and further surveillance and monitoring of this agent as a cause of CAP is warranted.

Figure 1

Epidemiologic distribution of different types of human adenoviruses. Most human adenovirus type 55 was identified during February and March, and it had epidemiologic characteristics similar to other types. No adenovirus pneumonia was found in November and December, the typical influenza season months.

Figure 2

Radiographic findings of four patients infected with different types of adenoviruses. A, An 18-year-old young man infected with human adenovirus (HAdV)-14. Chest CT scan showed patchy infiltrate, ground-grass opacity, and partial consolidation of left lower lobe. B, A 14-year-old boy infected with HAdV-55. Chest CT scan showed consolidation and ground-grass opacity of left lower lobe. C, A 15-year-old girl infected with HAdV-7. Chest CT scan showed patchy infiltrate and ground-grass opacity of left lower lobe. D, A 24-year-old man infected with HAdV-3. Chest CT scan showed consolidation and ground-grass opacity of right lower lobe. ys = years old.