Epidemiology of Adenovirus Outbreaks on College Campuses

Among college students, human adenoviruses should be considered as a cause for respiratory illness, according to a study published in Clinical Infectious Diseases.

Human adenoviruses are double-stranded DNA viruses comprising 7 species and > 100 types. The clinical manifestations of human adenoviruses include acute respiratory illness, fever, conjunctivitis, and gastroenteritis. The most common human adenoviruses types associated with upper and lower respiratory tract disease and conjunctivitis are types 4 and 7. The human adenoviruses-associated acute respiratory illness is typically mild, but can be severe by causing pneumonia, disseminated disease, and death. Human adenoviruses do not have a distinct seasonal pattern and congregate settings facilitate transmission.

Outbreaks of human adenovirus and associated acute respiratory illness have been well documented in congregate military settings, resulting in an oral, live, non-attenuated vaccine for types 4 and 7 being available to military personnel since 1971. However, there have been few reported human adenovirus outbreaks and human adenovirus-associated acute respiratory illness on college campuses, where people share similar living and social environments to those of military barracks. Between 2018 and 2019, state health departments identified increases in human adenovirus-associated acute respiratory illnesses at 5 college campuses in Maryland, Michigan, Pennsylvania, Virginia, and Wisconsin. Therefore, this study investigated these cases in the college campus setting to better understand human adenovirus epidemiology.

In total, 168 human adenovirus cases were included in this analysis. The patients investigated completed a questionnaire that included symptom presentation, social history, and absenteeism. In addition, medical records of the cases were reviewed. If respiratory specimens were available from the cases, they were categorized by human adenovirus type-specific real-time polymerase chain reaction assays; for some cases, whole genome sequencing was performed.

Results suggested that human adenoviruses should be considered as a potential cause of respiratory illness outbreaks on college campuses. Of the included cases, the median age was 19 years with a range from 17 to 22 years; most cases (61%) occurred in men. The most common findings included the following: 45 (67%) patients experienced pharyngitis/tonsillitis, 38 (57%) patients experienced fever ranging from 100- to 103-degrees Fahrenheit, and 35 (52%) patients experienced cervical lymphadenopathy.

A total of 11 patients were hospitalized, 10 had pneumonia, and 2 died. The 2 patients who died had disseminated type 7 infection with high viral loads in serum or plasma. A total of 98 (58%) patients completed the questionnaire and results showed that 81 (83%) of respondents lived in dormitories and 94 (97%) of respondents shared either a bedroom or common space with others. The median number of missed class days was 3 days and ranged from 1 to 20 days. At the time of the questionnaire, 79 respondents had recovered and reported a median illness duration of 10 days that ranged from 3 to 30 days. In total, 79% of patients were able to have their human adenovirus type identified; types 4 and 7 were equally detected with frequency varying by site. Furthermore, genome types 4a1 and 7d were identified by whole genome sequence analysis.

Overall, the study authors concluded that, “Understanding overall disease burden, risk, and risk factors for [human adenoviruses] illness are necessary to inform prevention strategies and to evaluate the potential utility of a vaccine in these settings.”

Reference

Kujawski SA, Lu X, Schneider E, et al. Outbreaks of adenovirus-associated respiratory illness on five college campuses in the United States [published online April 23, 2020]. Clin Infect Dis. 2020. doi:10.1093/cid/ciaa465/5823941