Adenovirus May Be Underestimated Cause of Acute Respiratory Disease

A recent study has shown that human adenovirus (HAdV) type 4 (HAdV-4) may be an underestimated cause of acute respiratory disease (ARD) among adults.

Adriana E. Kajon, PhD, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, and colleagues published the results of their study in the February 2018 issue of Emerging Infectious Diseases, CDC’s monthly peer-reviewed public health journal.

“As part of our ongoing collaborative efforts to describe the molecular epidemiology and determine the prevalence of HAdV-associated respiratory disease, we examined HAdV-4 isolates recovered from college students with acute febrile respiratory illness in New York and several adults with severe respiratory disease in other locations in the northeastern United States,” the authors write.

HAdV-4 is well recognized as a cause of febrile ARD in military settings in the United States and other countries.

However, recent data from the New York State Department of Health (NYSDOH) and the Centers for Disease Control and Prevention (CDC) have suggested that cases and case clusters of HAdV-4 respiratory infection may be on the rise in the northeastern United States.

In their study, Dr. Kajon and colleagues performed detailed molecular characterizations of 36 HAdV-4 isolates recovered from civilian adults with ARD in the northeastern United States over a 4-year period, ranging from 2011 to 2015.

Specimens came from college students, residents of long-term care facilities or nursing homes, a cancer patient, and young adults without co-morbidities. The individuals had severe respiratory disease, the authors note, and some died as a result of their illnesses.

The researchers identified 5 different genomic variants among the HAdV-4 isolates, 2 (4a1 and 4a2) of which had been previously identified in association with outbreaks of febrile respiratory illness among military recruits in the United States and were highly prevalent in the basic training environment before the adenovirus vaccination program resumed in 2011.

They also identified 2 previously unreported variants that were closely related to 4a1 (SmaI v) and 4a2 (SmaI/XhoI v), as well as a prototype-like variant distinguishable from the vaccine strain.

In an interview with Contagion^®, Dr. Kajon stressed the need to better understand the epidemiology of adenovirus respiratory infections in the United States.

Her laboratory is part of a unique team of collaborators that includes the CDC, NYSDOH, the Naval Health Research Center, and the Walter Reed Army Institute of Research. In the last several years, this team has been working “to address the characterization of outbreaks and cases of adenovirus respiratory infection of special interest to the public health community, due to the severity of the clinical presentation or the novel features of the detected virus,” she explained.

The results of this current study add to previously published data, showing that adenovirus infections may have been underestimated in their potential to result in severe disease in children and adults.

“The high sensitivity of molecular diagnostic platforms has increased our visibility of these infections,” said Dr. Kajon.

She hopes that the findings of this study will help increase clinicians’ awareness of the role of adenoviruses in the etiology of severe ARD. She also urges clinicians to consider requesting adenovirus testing in the diagnostic workup of cases of acute respiratory infection of considerable severity, especially during the flu season.

With regard to future studies in this area, Dr. Kajon shared that her team of collaborators “is interested in conducting a retrospective study to describe the most prevalent adenovirus types circulating in the United States in the last decade.”

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.