this study was approved by the ethics committee of the armed forces medical command , which waived the requirement of informed patients consent for this retrospective study . from july 18 to july 30 , 2009 , 18 out of 57 patients who presented with acute febrile respiratory illness ( fever of 38 or higher , and/or a cough or shortness of breath ) ( 8) , were confirmed with the pandemic h1n1 2009 influenza virus infection in a tertiary military hospital in south korea .
we retrospectively reviewed the medical charts , as well as the laboratory and radiologic findings of these patients .
all patients were young male soldiers with a mean age of 20 years ( age range : 19 to 22 years ) .
fifteen of the 18 patients confirmed with the pandemic h1n1 2009 influenza virus infection were from the same barrack , and they visited the emergency department due to acute febrile respiratory illness from july 18 to july 20 , 2009 .
the other three patients were from different barracks and were admitted with suspected cases of rhabdomyolysis after a long distance march ( n = 1 ) , acute gastroenterocolitis ( n = 1 ) , and acute febrile respiratory illness with leukocytopenia and thrombocytopenia ( n = 1 ) .
all three patients came into contact with one or more of the previously - mentioned patients lying in nearby beds in our hospital . among the 15 patients who presented to the emergency department with acute febrile respiratory illness ,
two patients had returned from a brief visit to their hometowns one week prior to the outbreak of acute febrile respiratory illness and were suspected as the source of the illness .
specimens from a nasopharyngeal swab ( n = 17 ) , and tracheal aspirate ( n = 1 ) were collected at the emergency department or wards when the 15 patients of the same barrack visited the emergency department , or when symptoms developed in the remaining three patients who came into contact with them .
reverse - transcriptase - polymerase - chain - reaction ( rt - pcr ) tests and additional viral cultures were performed in accordance with published guidelines from the who in all patients ( 8) . a malaria smear and triple antibody tests of hantann , leptospirosis , and tsutsugamushi virus were also performed to rule out other potential causes of fever , and revealed no remarkable abnormalities .
for the review of the clinical features , initial symptoms such as fever , cough , sputum , rhinorrhea , sore throat , myalgia , headache , dizziness , vomiting , and diarrhea were recorded . in turn , patient symptom progression while under treatment was also reviewed . for review of the laboratory data , the hematological analysis of the white blood cell ( wbc ) count , red blood cell ( rbc ) count , hemoglobin level , hematocrit level , platelet count , neutrophil count and the biochemical analysis of alkaline phosphatase ( alp ) , aspartate aminotransferase ( ast ) , alanine aminotransferase ( alt ) , creatine kinase ( ck ) , erythrocyte sedimentation rate ( esr ) , and c - reactive protein ( crp ) were recorded .
chest radiographs and thin - section ct examinations were obtained from 18 and 12 patients , respectively , prior to the administration of antiviral agents .
two out of the 12 patients undergoing thin - section cts received follow - up thin - section ct examinations a week after starting antiviral therapy .
all radiographic examinations were performed using digital radiographic equipment ( tdr4600-f80 ; gold mountain medical system , seoul , korea ) and a standardized technique ( 110 kv , 2 mas , and a 180-cm film - focus distance for the posteroanterior views ) .
thin - section cts of the thorax were performed using a 16 channel ct scanner ( brightspeed ; ge medical systems , wi ) , with the following parameters : 1.25 mm slice thickness with a 2.5 mm gap , supine position , scanning during inspiration , 6 seconds scan time , 120kv , auto ma .
all chest radiographs and thin - section ct images were reviewed by three experienced chest radiologists ( 8 , 10 , and 16 years of experience in chest radiology , respectively ) using a picture archiving and communication systems ( pacs ) viewer .
the presence of nodular opacity , consolidation ( focal , multifocal , or bilateral ) or interstitial patterns , distribution of findings including central ( inner two - thirds of lung ) or peripheral ( outer one - third of lung ) and upper , middle or lower lung zones , atelectasis , mediastinal abnormalities , and the presence or absence of a pleural effusion were analyzed ( 15 ) .
thin - section ct findings were interpreted using the descriptors proposed by the fleischer society nomenclature committee ( 16 ) .
ground - glass opacity ( ggo ) was defined as an increase in the lung parenchymal attenuation that did not obscure the underlying vascular architecture .
a nodule was defined as round opacity , at least moderately well - defined , and no more than 3 cm in diameter .
consolidation was defined as increased lung attenuation that obscured the underlying vasculature ( 16 ) .
the lesion size was described as small ( diameter , less than 1 cm ) , medium ( diameter , 1 to 3 cm ) , large ( diameter , 3 cm to 50% of the segment ) , or segmental ( 50% to 100% of the segment ) .
the sites were described by the name and number of involved segments of the lung .
location of the lesion was defined as peripheral if it was in the outer one - third of the lung ; otherwise , it was defined as central ( 17 ) .
attention was also paid to the presence of other abnormalities such as pleural effusion , lymphadenopathy , cavitation , calcification , or septal thickening .
from july 18 to july 30 , 2009 , 18 out of 57 patients who presented with acute febrile respiratory illness ( fever of 38 or higher , and/or a cough or shortness of breath ) ( 8) , were confirmed with the pandemic h1n1 2009 influenza virus infection in a tertiary military hospital in south korea .
we retrospectively reviewed the medical charts , as well as the laboratory and radiologic findings of these patients .
all patients were young male soldiers with a mean age of 20 years ( age range : 19 to 22 years ) .
fifteen of the 18 patients confirmed with the pandemic h1n1 2009 influenza virus infection were from the same barrack , and they visited the emergency department due to acute febrile respiratory illness from july 18 to july 20 , 2009 .
the other three patients were from different barracks and were admitted with suspected cases of rhabdomyolysis after a long distance march ( n = 1 ) , acute gastroenterocolitis ( n = 1 ) , and acute febrile respiratory illness with leukocytopenia and thrombocytopenia ( n = 1 ) .
all three patients came into contact with one or more of the previously - mentioned patients lying in nearby beds in our hospital . among the 15 patients who presented to the emergency department with acute febrile respiratory illness
, two patients had returned from a brief visit to their hometowns one week prior to the outbreak of acute febrile respiratory illness and were suspected as the source of the illness .
specimens from a nasopharyngeal swab ( n = 17 ) , and tracheal aspirate ( n = 1 ) were collected at the emergency department or wards when the 15 patients of the same barrack visited the emergency department , or when symptoms developed in the remaining three patients who came into contact with them .
reverse - transcriptase - polymerase - chain - reaction ( rt - pcr ) tests and additional viral cultures were performed in accordance with published guidelines from the who in all patients ( 8) . a malaria smear and triple antibody tests of hantann , leptospirosis , and tsutsugamushi virus were also performed to rule out other potential causes of fever , and revealed no remarkable abnormalities .
two authors retrospectively reviewed the clinical and laboratory findings . for the review of the clinical features ,
initial symptoms such as fever , cough , sputum , rhinorrhea , sore throat , myalgia , headache , dizziness , vomiting , and diarrhea were recorded . in turn , patient symptom progression while under treatment was also reviewed . for review of the laboratory data , the hematological analysis of the white blood cell ( wbc ) count , red blood cell ( rbc ) count , hemoglobin level , hematocrit level , platelet count , neutrophil count and the biochemical analysis of alkaline phosphatase ( alp ) , aspartate aminotransferase ( ast ) , alanine aminotransferase ( alt ) , creatine kinase ( ck ) , erythrocyte sedimentation rate ( esr ) , and c - reactive protein ( crp ) were recorded .
chest radiographs and thin - section ct examinations were obtained from 18 and 12 patients , respectively , prior to the administration of antiviral agents .
two out of the 12 patients undergoing thin - section cts received follow - up thin - section ct examinations a week after starting antiviral therapy .
all radiographic examinations were performed using digital radiographic equipment ( tdr4600-f80 ; gold mountain medical system , seoul , korea ) and a standardized technique ( 110 kv , 2 mas , and a 180-cm film - focus distance for the posteroanterior views ) .
thin - section cts of the thorax were performed using a 16 channel ct scanner ( brightspeed ; ge medical systems , wi ) , with the following parameters : 1.25 mm slice thickness with a 2.5 mm gap , supine position , scanning during inspiration , 6 seconds scan time , 120kv , auto ma .
all chest radiographs and thin - section ct images were reviewed by three experienced chest radiologists ( 8 , 10 , and 16 years of experience in chest radiology , respectively ) using a picture archiving and communication systems ( pacs ) viewer .
decisions were reached by consensus . to review chest radiographs , the presence of nodular opacity , consolidation ( focal , multifocal , or bilateral ) or interstitial patterns , distribution of findings including central ( inner two - thirds of lung ) or peripheral ( outer one - third of lung ) and upper , middle or lower lung zones , atelectasis , mediastinal abnormalities , and the presence or absence of a pleural effusion were analyzed ( 15 ) .
thin - section ct findings were interpreted using the descriptors proposed by the fleischer society nomenclature committee ( 16 ) .
ground - glass opacity ( ggo ) was defined as an increase in the lung parenchymal attenuation that did not obscure the underlying vascular architecture .
a nodule was defined as round opacity , at least moderately well - defined , and no more than 3 cm in diameter .
consolidation was defined as increased lung attenuation that obscured the underlying vasculature ( 16 ) .
the lesion size was described as small ( diameter , less than 1 cm ) , medium ( diameter , 1 to 3 cm ) , large ( diameter , 3 cm to 50% of the segment ) , or segmental ( 50% to 100% of the segment ) .
the sites were described by the name and number of involved segments of the lung .
location of the lesion was defined as peripheral if it was in the outer one - third of the lung ; otherwise , it was defined as central ( 17 ) .
attention was also paid to the presence of other abnormalities such as pleural effusion , lymphadenopathy , cavitation , calcification , or septal thickening .
the clinical course and outcome of all patients are summarized in figure 1 . in the analysis of 15 patients who visited the emergency department , the mean interval between
symptom onset and emergency room visit was 1.7 days  1.5 days ( range , 0 to 5 days ) . in the analysis of all 18 patients ,
the mean interval between symptom onset and the start of oseltamivir phosphate ( tamiflu , roche , basel , switzerland ) administration was 3.9  1.6 days ( range , 1 to 7 days ) .
in addition , the mean interval between symptom onset and symptom improvement was 4.7  1.7 days ( range , 2 to 8 days ) .
the clinical characteristics of the 18 patients in our study are summarized in tables 1 and 2 .
all patients presented with high fever ( > 38.0 , median value and range ; 38.5 and 38.2 - 39.5 ) , with common accompanying symptoms including coughing ( 78% ) , rhinorrhea ( 89% ) , sore throat ( 78% ) , myalgia ( 78% ) , vomiting ( 50% ) or diarrhea ( 56% ) .
seventeen out of the 18 patients showed wbc counts within normal limits , whereas one patient showed leukocytopenia .
in addition , thrombocytopenia and lymphocytopenia were present in three of 18 ( 17% ) and 12 of 18 patients ( 67% ) , respectively .
no abnormality was noted for the rbc count , hemoglobin level , hematocrit level , platelet count , and neutrophil count .
however , all patients showed elevated crp values . after the diagnosis of the pandemic h1n1 2009 influenza virus infection through rt - pcr tests and additional viral cultures , all patients were treated with oseltamivir phosphate .
of the 18 patients , 16 rapidly recovered after the administration of the antiviral agent . in the two remaining patients
, the symptoms started to improve prior to oseltamivir phosphate treatment . among our study population , one patient presented with high fever , severe nocturnal cough , and blood tinged sputum , and the respiratory symptoms eventually progressed into acute respiratory distress syndrome ( ards ) , which further led him to receive mechanical ventilation ( case no .
a retrospective medical chart review revealed that this patient was a solider serving in a different unit from the majority of the other patients and had been in contact with a patient with pandemic h1n1 2009 influenza virus infection lying in a nearby bed in our hospital prior to symptom aggravation .
the laboratory data of this patient showed leukocytopenia , thrombocytopenia , and an increased ck level .
he was initially treated with antibiotics such as macrolide and a 3rd generation cephalosporin under suspicion of bacterial pneumonia , which was never confirmed .
five days after contact with a patient with pandemic h1n1 2009 influenza viral infection , severe respiratory distress presented and a laboratory analysis from the tracheal aspirate performed during endotracheal intubation confirmed the pandemic h1n1 2009 influenza virus infection . following the administration of oseltamivir phosphate and antibiotics , the patient 's symptoms improved and was taken off mechanical ventilation five days after antiviral agent administration .
sixteen out of 18 patients in our study population showed no abnormalities on chest radiographs .
moreover , only two patients in our study showed abnormal findings of a small central nodular opacity in the right upper lung zone in one ( fig .
2a ) , and consolidations in the left middle lung and both lower lungs in the other ( fig .
of these six patients , five ( 83% ) had small ggos ; four patients had them in the upper lobe of the lung and one had a small ggo discovered in the lower lobe of the lung .
also , in four out of the five patients with small ggos ( 80% ) , the lesions were localized in the periphery of the lung , and two of the five patients also showed bilateral involvement . for segmental involvement in terms of lesion size
, three patients showed one segment , one patient showed two segments , one patient showed three segments , and one patient showed eight segments .
nodules were observed in all patients ( 100% ) , which were small in size with showing poorly defined margins ( fig .
in addition , the nodule was a solitary finding in one patient ( 17% ) , which was located in the peripheral area of the right upper lobe . the patient who progressed into ards had bilateral lobar consolidations combined with ggos , nodules , and bilateral pleural effusion ( fig .
one other patient showed right paratracheal lymphadenopathy . in our study , there was no evidence of calcification , mass , cavitation , or septal thickenings in any of the patients .
the thin - section ct findings of the 12 patients are summarized in table 3 . in two patients , follow - up thin section ct images acquired one week after the start of antiviral therapy showed complete resolution or a remarkable decrease in size and opacity of the previously observed ggos and nodules ( fig .
the clinical course and outcome of all patients are summarized in figure 1 . in the analysis of 15 patients who visited the emergency department , the mean interval between
symptom onset and emergency room visit was 1.7 days  1.5 days ( range , 0 to 5 days ) . in the analysis of all 18 patients ,
the mean interval between symptom onset and the start of oseltamivir phosphate ( tamiflu , roche , basel , switzerland ) administration was 3.9  1.6 days ( range , 1 to 7 days ) .
in addition , the mean interval between symptom onset and symptom improvement was 4.7  1.7 days ( range , 2 to 8 days ) .
the clinical characteristics of the 18 patients in our study are summarized in tables 1 and 2 .
all patients presented with high fever ( > 38.0 , median value and range ; 38.5 and 38.2 - 39.5 ) , with common accompanying symptoms including coughing ( 78% ) , rhinorrhea ( 89% ) , sore throat ( 78% ) , myalgia ( 78% ) , vomiting ( 50% ) or diarrhea ( 56% ) .
seventeen out of the 18 patients showed wbc counts within normal limits , whereas one patient showed leukocytopenia .
in addition , thrombocytopenia and lymphocytopenia were present in three of 18 ( 17% ) and 12 of 18 patients ( 67% ) , respectively .
no abnormality was noted for the rbc count , hemoglobin level , hematocrit level , platelet count , and neutrophil count .
however , all patients showed elevated crp values . after the diagnosis of the pandemic h1n1 2009 influenza virus infection through rt - pcr tests and additional viral cultures , all patients were treated with oseltamivir phosphate .
of the 18 patients , 16 rapidly recovered after the administration of the antiviral agent . in the two remaining patients
, the symptoms started to improve prior to oseltamivir phosphate treatment . among our study population , one patient presented with high fever , severe nocturnal cough , and blood tinged sputum , and the respiratory symptoms eventually progressed into acute respiratory distress syndrome ( ards ) , which further led him to receive mechanical ventilation ( case no .
a retrospective medical chart review revealed that this patient was a solider serving in a different unit from the majority of the other patients and had been in contact with a patient with pandemic h1n1 2009 influenza virus infection lying in a nearby bed in our hospital prior to symptom aggravation .
the laboratory data of this patient showed leukocytopenia , thrombocytopenia , and an increased ck level .
he was initially treated with antibiotics such as macrolide and a 3rd generation cephalosporin under suspicion of bacterial pneumonia , which was never confirmed .
five days after contact with a patient with pandemic h1n1 2009 influenza viral infection , severe respiratory distress presented and a laboratory analysis from the tracheal aspirate performed during endotracheal intubation confirmed the pandemic h1n1 2009 influenza virus infection . following the administration of oseltamivir phosphate and antibiotics , the patient 's symptoms improved and was taken off mechanical ventilation five days after antiviral agent administration .
sixteen out of 18 patients in our study population showed no abnormalities on chest radiographs .
moreover , only two patients in our study showed abnormal findings of a small central nodular opacity in the right upper lung zone in one ( fig .
2a ) , and consolidations in the left middle lung and both lower lungs in the other ( fig .
of these six patients , five ( 83% ) had small ggos ; four patients had them in the upper lobe of the lung and one had a small ggo discovered in the lower lobe of the lung .
also , in four out of the five patients with small ggos ( 80% ) , the lesions were localized in the periphery of the lung , and two of the five patients also showed bilateral involvement . for segmental involvement in terms of lesion size
, three patients showed one segment , one patient showed two segments , one patient showed three segments , and one patient showed eight segments .
nodules were observed in all patients ( 100% ) , which were small in size with showing poorly defined margins ( fig .
in addition , the nodule was a solitary finding in one patient ( 17% ) , which was located in the peripheral area of the right upper lobe .
the patient who progressed into ards had bilateral lobar consolidations combined with ggos , nodules , and bilateral pleural effusion ( fig .
one other patient showed right paratracheal lymphadenopathy . in our study , there was no evidence of calcification , mass , cavitation , or septal thickenings in any of the patients .
the thin - section ct findings of the 12 patients are summarized in table 3 . in two patients , follow - up thin section ct images acquired one week after the start of antiviral therapy showed complete resolution or a remarkable decrease in size and opacity of the previously observed ggos and nodules ( fig .
with increasing concern over the spread of the pandemic h1n1 2009 influenza virus infection worldwide , detailed knowledge of both its clinical and radiologic features can assist the clinical practice and decision - making of physicians facing this emerging pandemic infectious disease .
in addition , preparation for this pandemic infectious disease among institutionalized populations in semi - closed settings such as schools , dormitories , military barracks , or prisons should be made since this infection can spread very rapidly and may quickly become unmanageable without prompt and proper management in the early stages of disease spread . in this study , we attempt to describe one incidence of a military outbreak of the pandemic h1n1 2009 influenza virus with a focus on the clinical and radiological features of these patients , as well as the outcome of treatment .
we found common clinical features for all patients with the pandemic h1n1 2009 influenza virus infection in the present study , which included a high fever with accompanying symptoms of cough , rhinorrhea , sore throat , myalgia , or gastrointestinal symptoms such as vomiting or diarrhea .
these findings are similar to the symptoms of other influenzas ( 8) and those found in previous studies that dealt with unspecified populations ( 3 , 5 , 9 - 13 ) .
generally , laboratory tests , with the exception of serology and culture examinations , are not useful for the specific diagnosis of influenza .
leukocyte counts are variable according to stage ; frequently low during the early stages of illness , and later become normal or slightly elevated ( 15 ) . in the present series , there were no patients with elevated wbc counts and 67% of patients showed lymphocytopenia .
these findings are consistent with those found in previous studies that dealt with unspecified populations ( 3 , 5 ) .
one additional diagnostic laboratory feature we were able to find was an elevated crp level while both the esr and wbc counts remained within a normal range in all patients in our study with pandemic h1n1 2009 influenza virus infection .
we believe that elevated crp levels , combined with a lack of leukocytosis or elevated esr , may be characteristic of patients with the pandemic h1n1 2009 influenza virus infection , although these laboratory tests might generally not be able to render a specific diagnosis of this influenza viral infection ( 14 ) .
further detailed comparative studies with a larger number of patients would be required to fully explore this issue .
most patients in our study did not show a severe hospital course , although one patient 's symptoms aggravated into ards and needed mechanical ventilation before laboratory tests revealed that he had the pandemic h1n1 2009 influenza virus infection .
we considered the possibility that co - infection of the pandemic h1n1 2009 influenza virus with other unknown respiratory pathogens under the leukocytopenia status could have attributed to this symptom aggravation ( 9 , 10 ) , particularly as he was a soldier serving in a different unit from the majority of other patients .
in addition , the symptom aggravation had occurred after he had been in contact with a patient infected with the pandemic h1n1 2009 influenza virus and there were no pandemic h1n1 2009 influenza virus cases in the unit the patient had been enrolled in . however , since his respiratory symptoms and high fever did not respond to other previous antibiotic treatment , there is still the possibility that the disease course in this case could have been solely due to a severe manifestation of the pandemic h1n1 2009 influenza virus infection . in the present study ,
chest radiographs were abnormal in two of 18 patients with h1n1 , which was less frequent than that of a previous report , which showed a 42% rate of chest radiograph abnormality ( 12 ) .
this suggests that negative findings on chest radiographs can not rule out the possibility of the pandemic h1n1 2009 influenza virus infection , particularly in its early stage or for an uncomplicated influenza infection ( 14 ) .
thin - section ct examination results revealed that abnormal findings were found in six out of 12 patients ( 50% ) .
the most common ct abnormalities included small ggos in five out of six patients and nodules in all six patients .
however , in the previous studies ( 12 , 13 ) , multifocal consolidations ( two of seven patients and 50% ) and ggos ( two of seven patients and 25% ) were the most common ct findings of the pandemic h1n1 2009 influenza virus infection . the differences between the present study and previous studies could be attributed to the fact that radiological examinations in the present study were performed at the initial presentation , and probably the early stages of the disease ; whereas in previous studies ( 12 , 13 ) , radiological examinations were performed at various times after symptom onset . in our study , there was one patient with bilateral lobar consolidations , which progressed into ards .
other investigators ( 3 ) also reported similar radiographic features in patients who progressed into ards .
although extensive consolidations in the lung might be severe manifestations of primary viral pneumonia from the pandemic h1n1 2009 influenza virus infection , there still remains the possibility of combined pneumonia caused by other pathogens or pulmonary manifestations of ards ( 14 ) .
the clinical courses and outcomes of patients in our study with the pandemic h1n1 2009 influenza virus infection were much better than those of previously reported cases ( 3 , 4 ) .
furthermore , according to military rule , any problems concerning health must be notified to the medical department immediately , and thus , our patients may have been detected at an earlier stage of the disease course than would be found for the general population . in comparison with a previous report ( 3 ) that showed a high mortality rate in patients with the pandemic h1n1 2009 influenza virus infection , the interval between symptom onset and the emergency department visit ( mean 1.7 days in 15 among 18 patients ) and symptom onset and the start of antiviral agent therapy ( mean 3.9 days ) were shorter .
therefore , we conclude that an early diagnosis and early antiviral management can improve the clinical course and outcome of the pandemic h1n1 2009 influenza virus infection . however , to understand the detailed relationship between symptom onset to admission or antiviral management and clinical courses or outcomes , further study , including a comparative analysis with a large case series , is warranted . in our series , most patients ( 15 out of 18 ) were from the same barrack , a semi - closed setting ; whereas , the three remaining patients from different barracks were thought to be infected from these 15 patients .
clinical and laboratory results from this homogeneous study population can be helpful in understanding the clinical characteristics of the pandemic h1n1 2009 influenza virus infection in semi - closed settings and in institutionalized populations composed of a young healthy population , such as in schools , dormitories , prisons , or military units .
furthermore , this report demonstrated that a prompt diagnosis and treatment resulted in excellent outcomes and could provide as an example for the detection and management strategy for cluster outbreaks of this virus .
however , there may be limitations in applying these results to the larger general population . in conclusion , in a population of healthy young adults , elevated crp with normal esr and wbc levels combined with ggos and nodules on thin - section ct scans may indicate early signs of infection by the pandemic h1n1 2009 influenza virus .
 objectiveto describe detailed clinical and radiological features of the pandemic h1n1 2009 influenza viral infection among healthy young males in a semi - closed institutionalized setting.materials and methodsa total of 18 patients confirmed with the pandemic h1n1 2009 influenza virus infection from july 18 to july 30 , 2009 were enrolled in this study . 
 each patient underwent an evaluation to determine detailed clinical and radiological features.resultsall patients presented with high fever ( > 38.0 ) , with accompanying symptoms of cough , rhinorrhea , sore throat , myalgia and diarrhea , and increased c - reactive protein ( crp ) values with no leukocytosis nor elevated erythrocyte sedimentation rate ( esr ) . 
 all patients , including one patient who progressed into acute respiratory distress syndrome , were treated with oseltamivir phosphate and quickly recovered from their symptoms . 
 chest radiographs showed abnormalities of small nodules and lobar consolidation in only two out of 18 patients . 
 however , six of 12 patients who underwent thin - section ct examinations showed abnormal findings for small ground - glass opacities ( ggos ) in addition to poorly - defined nodules with upper lobe predominance.conclusionin a population of healthy young adults , elevated crp with normal esr and white blood cell levels combined with ggos and nodules on thin - section ct scans may indicate early signs of infection by the pandemic h1n1 2009 influenza virus . 
MATERIALS AND METHODS
Patients
Laboratory Confirmation
Review of Clinical and Laboratory Characteristics
Radiologic Examinations
Review of Chest Radiographs and Thin-Section CT Images
RESULTS
Clinical and Laboratory Characteristics of Patients
Chest Radiograph and Thin-Section CT Findings
DISCUSSION