Human adenovirus type 4, an influenza-like illness usually found in isolated military settings, was detected among the general population, such as college students, residents of long-term care facilities and other young adults, researchers found.
Thirty-six isolates of human adenovirus type 4, or HAdV-4, were found in adults outside of military facilities, reported Adriana E. Kajon, PhD, of Lovelace Respiratory Research Institute in Albuquerque, New Mexico, and colleagues.
While most of these were the most common genome types found among military recruits, certain novel variants were identified among college students and young adults from upstate New York, the authors wrote in Emerging Infectious Diseases.
HAdV-4 is one cause of acute respiratory disease and ocular disease, the authors said. They noted that a vaccine against this virus was exclusively licensed for military use, although HAdV-4 vaccination protocols were discontinued for 15 years, until they were reinstated in 2011. But the authors said there is no surveillance for the disease outside of the military, which makes it difficult to figure out the burden of disease linked to it among civilians.
“The apparent increased frequency of detection of cases and case clusters of HAdV-4 respiratory infection in the northeastern United States … caught our attention,” they wrote.
Researchers obtained specimens that were positive for HAdV-4. Patients had acute respiratory disease or influenza-like illness characterized by a fever, cough, sore throat and other respiratory symptoms. These cases were identified by the New York State Department of Health as part of the CDC’s influenza-like illness surveillance network or “special HAdv cases” referred to the CDC for investigation.
Identified cases came from an outbreak at a long-term care facility in Boston, adults with severe pneumonia in Connecticut and New York, college students in New York, and additional cases among other adults, including a nursing home patient, a fatal case of a patient at a cancer care center, and acute respiratory disease in a teenager at a pediatric clinic.
Among these 36 cases, authors identified five genomic variants — some of which were associated with outbreaks and others that were “epidemiologically unlinked” cases of acute respiratory disease. Of these, genomic variant 4a1 was isolated from 18 of 36 specimens, while genomic variant 4a2 was isolated from 12 of 36 specimens. Both variants were highly prevalent in basic training facilities prior to the reinstatement of vaccination protocols in 2011, the authors said.
But they also found two previously unreported variants described as “closely related” to 4a1 and 4a2 among certain college students in upstate New York, and one strain that was similar to a vaccine-like strain of the virus in an 18 year-old at a physician’s office.
They speculated on the potential reasons for this virus in the civilian population, either that the public could have been exposed to non-attenuated vaccine strains through fecal shedding from military personnel who were vaccinated from 1971 to 1997, or that these variants were circulating at low prevalence among civilian communities since the 1950s, when they were first identified, the authors said.
They added that due to the severity of clinical presentation in some of these cases, the vaccine licensed for military use against HAdV-4 should be considered “a potentially valuable resource” to prevent disease in closed communities, like college, summer camps, and long-term care facilities.
“Our data and reports of cases of severe [acute respiratory disease] associated with HAdV-4 infection in Italy and Singapore suggest that the role of this HAdV type in the etiology of adult civilian ARD might have been underestimated in the absence of access to molecular…typing resources,” they wrote.
They recommended including human adenovirus in differential diagnostic panels to ensure that patients with influenza-like symptoms, but who test negative for the flu, are not treated with anti-influenza agents.
The study was supported by the CDC.
Kajon disclosed no relevant relationships with industry. One co-author disclosed support from the NIH.