we obtained data regarding temporal trends in fri incidence from military sentinel surveillance , which has been monitoring weekly fri rates since october 2011 .
monthly numbers of patients with pneumonia ( inpatients , outpatients , and emergency room patients ) were extracted from a computerized data warehouse that stores data from all military hospitals .
we identified pneumonia cases by using the international classification of diseases and related health problems , 10th revision , codes j12j18 .
the influenza season , which starts in october and ends the following may , was used as a surrogate for the hadv season in this study .
the trends in fri rates showed an unusual surge during the 201415 influenza season ( figure 1 , panel a ) .
the fri rate increased for 15 weeks in the 201415 season , compared with 10 weeks in the 201213 season and 5 weeks in the 201314 season .
peak fri rate in the 201415 season ( 10.4% ) was higher than rates in the preceding 2 seasons ( 4.7% and 7.5% ) .
the numbers of pneumonia cases in 201415 and 201516 seasons were 3,140 and 3,145 patients , respectively , a 191% increase from the mean number during 3 preceding seasons .
a ) weekly febrile respiratory illness ( fri ) rate ( solid line ) and monthly number of pneumonia patients ( dashed line ) in the south korea military , 20112016 .
b ) positive rate of human adenovirus from respiratory specimens ( red line ) and the number of respiratory virus pcr requested ( blue bar ) from a tertiary military hospital , south korea , 20142016 . the rate and number for each month
a multiplex real - time pcr for identifying 15 viruses from respiratory specimens was introduced at the armed forces capital hospital , the only tertiary hospital in the south korea military health care system ( detailed methods in technical appendix ) .
a total of 1,484 nonduplicate specimens were tested by the end of may 2016 ( figure 1 , panel b ; technical appendix table 1 , figure ) .
hadv was identified in 490 ( 33.0% ) of total specimens , and it accounted for 79.7% ( 282/354 ) and 53.2% ( 150/282 ) of positive results in the 201415 and 201516 seasons , respectively .
we reviewed the demographic and clinical information of 878 military patients with fri or pneumonia who were tested for respiratory viruses from october 2014 through may 2016 ( tables 1 , 2 ) .
soldiers of lower rank were markedly more likely to infected with hadv ; soldiers serving in the air force were less likely .
patients who had been referred from other hospitals were twice as likely to be hadv - infected than patients who visited the armed forces capital hospital directly .
rhinorrhea , sore throat , diarrhea , and nausea / vomiting were more common in patients with hadv infection .
the proportion of patients with pneumonia and the hospitalization rate did not differ between those with and without hadv infection .
however , hadv - infected patients had a significantly higher risk of requiring intensive care or mechanical ventilator support . in the hadv - infected group ,
8 patients required intubation and 1 died ; no one in the noninfected group died or required intubation .
length of hospital stay was also significantly longer among those the hadv - infected group than among those in the noninfected group ( 12.6 vs. 9.4 days ) .
hadv , human adenovirus ; na , not available ; or , odds ratio ; pfc , private first class .
hadv , human adenovirus ; na , not available ; or , odds ratio.n = 877 . 
we conducted molecular typing by the sequencing of hexon and fiber genes with 74 hadv - positive respiratory specimens collected from march through june 2016 ( methods and general characteristics of the patients are available in the technical appendix table 2 ) . among them , 49 samples were successfully sequenced ( genbank numbers in online technical appendix ) .
phylogenetic analyses showed that all 49 hadv strains from south korea clustered with hadv-55 strains from china , singapore , taiwan , spain , and the united states ( figure 2 ) .
phylogenetic analysis of human adenoviruses based on the partial nucleotide sequences of hexon ( a ) and fiber ( b ) genes , south korea , 2016 .
phylogenetic trees were generated by the neighbor - joining method , using the kimura 2-parameter method .
the percentage of replicate trees in which the associated taxa clustered together in the bootstrap test ( 1,000 replicates ) are shown next to the branches .
hadv is a well - known major cause of fri in the military , accounting for > 50% of fri and pneumonia cases in military recruits ( 1 ) .
our study also confirmed the predominance of hadv , which was identified in 49.1% of specimens from patients with fri or pneumonia .
these findings are similar to those of previous studies from south korea and the united states ( 9,10 ) .
the most notable finding of our study is the emergence of hadv-55 in the south korea military .
hadv-55 is a novel type that has been associated with a severe clinical course and death in healthy young adults ( 7,8 ) .
we also found that hadv infection was associated with intensive care , mechanical ventilator support , and longer hospital stay .
in addition , we found that the only patient who died was hadv infected . from a molecular perspective , hadv-55 is a novel type with a hexon gene recombination between hadv-11 and hadv-14 ( 11 ) .
phylogenetic analysis by using the hexon and fiber gene sequence of 49 strains collected in our study showed that they clustered with previously reported hadv-55 strains .
spread of infection of traditionally military - associated hadv types into civilians has been recently reported in the united states and china ( 3,12,13 ) .
thus , surveillance of hadv types among both military and civilian populations is warranted ; such measures are being implemented by the us centers for disease control and prevention ( atlanta , ga , usa ) ( 12 ) .
first , our findings may not be generalizable due to the retrospective nature of the study
. however , the military health system in south korea provides healthcare exclusively to all military personnel ; therefore , epidemiologic information gathered from our surveillance is accurate and comprehensive .
second , we conducted molecular typing with samples collected from february 2016 , which was substantially later than the onset of the epidemic .
however , hadv-55 had already been identified in a case series from our center during june 2014may 2015 ( 8) . because evidence shows that hadv-55 has been already circulating since early 2014 ,
we believe we can assume that hadv-55 was the causative agent of the outbreak described in this study .
previously , the hadv typing study conducted in 2007 reported hadv-7 as the most prevalent type ( 14 ) .
lack of continuous surveillance makes it difficult to estimate exactly when this novel type was introduced into south korea .
further genomic analysis of the collected samples and enhanced surveillance , including of civilian populations , would provide more information on the epidemiology of hadv infection .
detailed methods of the study of febrile respiratory illness associated with human adenovirus in south korea military , 20142016 .
 an outbreak of febrile respiratory illness associated with human adenovirus ( hadv ) occurred in the south korea military during the 201415 influenza season and thereafter . molecular typing and phylogenetic analysis of patient samples identified hadv type 55 as the causative agent . 
 emergence of this novel hadv necessitates continued surveillance in military and civilian populations . 
The Study
Conclusions
None