Outbreak of Acute Respiratory Illness Associated With Human Adenovirus Type 4 at the United States Coast Guard Academy, 2019

Abstract

Background Although a human adenovirus (HAdV) vaccine is available for military use, officers-in-training are not routinely vaccinated. We describe an HAdV-associated respiratory outbreak among unvaccinated cadets at the U.S. Coast Guard Academy and its impact on cadet training. Methods We defined a case as a cadet with new onset cough or sore throat during August 1–October 4, 2019. We reviewed medical records and distributed a questionnaire to identify cases and to estimate impact on cadet training. We performed real-time PCR testing on patient and environmental samples and whole genome sequencing on a subset of positive patient samples. Results Among the 1,072 cadets, 378 (35%) cases were identified by medical records (n=230) or additionally by the questionnaire (n=148). Of the 230 cases identified from medical records, 138 (60%) were male and 226 (98%) had no underlying conditions. From questionnaire responses, 113/228 (50%) cases reported duty restrictions. Of cases with respiratory specimens, 36/50 (72%) were HAdV positive; all 14 sequenced specimens were HAdV-4a1. Sixteen (89%) of 18 environmental specimens from the cadet dormitory were HAdV-positive. Conclusions The HAdV-4-associated outbreak infected a substantial number of cadets and significantly impacted cadet training. Routine vaccination could prevent HAdV respiratory outbreaks in this population.

Clustered Cases of Human Adenovirus types 4, 7 and 14 Infections during the 2018 - 2019 Season revealed by US Department of Defense Respiratory Pathogen Surveillance and Whole Genome Sequencing

“…The only difference is position 19555 A/G, corresponding to hexon I461V. The subclade of isolate 21947 and five other isolates shares almost identical sequence with viruses that caused outbreaks in US Naval Academy in 2016 (MG030483) and US Coast Guard in 2019 (MT771648) (4, 8). One unique finding in this study is a novel 18 nucleotides long deletion presents in the 3’-terminal inverted terminal repeat (ITR) at position 35927 of HAdV4 isolate 21984_S4TF75 (OM649206), while the 5’-terminal ITR remains unchanged.…”

“…HAdV types 4, 7 and 14 were reported causing ARI in the military (4, 8, 17). This study identified these three adenoviruses in one season, 2018 - 2019.…”

“…Respiratory HAdV types 3, 4, 7, 11, 14, 21 and the more recent type 55 have been reported causes of ARI outbreaks in the US and in other countries (1,(4)(5)(6). HAdV ARI outbreaks in the US were documented in case reports and retrospective and prospective analyses (4,(6)(7)(8)(9). Active surveillance on respiratory HAdV infection with detailed characterization is desired to inform mitigation measures to protect high risk populations (10).…”

“…However, diseases associated with HAdVs, in particular, the rate of acute respiratory illnesses (ARI) caused by respiratory HAdVs, are believed to be underreported in the general population. Respiratory HAdV types 3, 4, 7, 11, 14, 21 and the more recent type 55 have been reported causes of ARI outbreaks in the US and in other countries (1,(4)(5)(6). HAdV ARI outbreaks in the US were documented in case reports and retrospective and prospective analyses (4,(6)(7)(8)(9).…”

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Human adenoviruses (HAdV) are genetically diverse and can infect a number of tissues with severities varied from mild to fatal. HAdV types 3,4, 7,11,14,21 and 55 were associated with acute respiratory illnesses (ARI) outbreaks in the US and in other countries. The risk of outbreaks can be effectively controlled by HAdV vaccination or mitigated by screening and preventive measures.

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