aard Allergy, Asthma & Respiratory Disease Allergy Asthma Respir Dis 2288-0402 2288-0410 The Korean Academy of Pediatric Allergy and Respiratory Disease; The Korean Academy of Asthma 10.4168/aard.2018.6.1.47 aard-6-47 Original Article Bronchiolitis severity according to the infected viruses LeeSu Jin ParkSang Kyu KimJi Hyun ChoSung Min Department of Pediatrics, Dongguk University Ilsan Hospital, Goyang, Korea Correspondence to: Ji Hyun Kim https://orcid.org/0000-0001-8493-2881 Department of Pediatrics, Dongguk University Ilsan Hospital, 27 Dongguk-ro, Ilsandong-gu, Goyang 10326, Korea Tel: +82-31-961-7190, Fax: +82-31-961-7188, E-mail: eogurdl@gmail.com 12018 512018 61 4753 10032017 24102017 24102017 Copyright © 2018 The Korean Academy of Pediatric Allergy and Respiratory Disease; The Korean Academy of Asthma 2018 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose

The aim of this study was to evaluate the severity of disease in children with acute bronchiolitis according to the type of infected virus.

 Methods

From November 2007 to May 2015, 768 patients under 2 years of age who underwent real time-polymerase chain reaction of nasopharyngeal aspirates admitted to the Department of Pediatrics of Dongguk University Ilsan Hospital for acute bronchiolitis were enrolled. Severe bronchiolitis was defined as presence of one or more kinds among tachypnea, chest retraction, needs of O2 inhalation or ventilator care.

 Results

The severity of bronchiolitis was increased with shorter fever duration (P <0.001) and previous wheezing episodes (P =0.005). In the case of single infection, respiratory syncytial virus (RSV) A only increased the severity of acute bronchiolitis (P =0.012). However, the severity of illness decreased when RSV A coinfected with adenovirus (P =0.034), human rhinovirus (P=0.038), or human coronavirus NL63 (P=0.042). On the other hand, when human rhinovirus was coinfected with enterovirus (P=0.013) or parainfluenza 3 (P=0.019), the severity was increased. When human metapneumovirus coinfected with human bocavirus, the severity was increased (P=0.038).

 Conclusion

Acute bronchiolitis was associated with increased severity only when RSV A infected solely, but several viruses increased or decreased the severity when coinfection occurred. Therefore, it may be helpful in predicting the course of the acute bronchiolitis according to the affected virus.

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Year-round change of acute bronchiolitis with 16 respiratory viruses isolated for 768 hospitalized children.

Clinical characteristics of hospitalized children with acute bronchiolitis

Characteristic Number (%)
Sex  
 Female 287 (37.4)
 Male 481 (62.6)
Age (yr)  
 ≤1 583 (75.9)
 >1, <2 185 (24.1)
Hospitalization period (day)  
 <3 96 (12.5)
 4 188 (24.5)
 5 169 (22)
 6 132 (17.2)
 7 58 (7.6)
 ≥8 125 (16.3)
Fever (day)  
 None 343 (44.7)
 1 94 (12.2)
 2 86 (11.2)
 ≥3 245 (31.8)
Ventilator care, yes 62 (8.1)
Siblings, yes 440 (57.3)

Clinical characteristics of hospitalized children with acute bronchiolitis analyzed according to disease severity

Characteristic Nonsevere (n=269) Severe (n=499) P-value
Age (mo)∗ 3.39 2.62 0.054
Hospitalization period (day)∗ 4.2 6.35 <0.001
Fever (day)∗ 2.20 1.60 <0.001
ICU hospitalization (day)∗ 0 0.05 0.001
CRP (mg/dL)∗ 1.05 1.20 0.261
Lymphocyte (%)∗ 55.99 52.94 0.006
Male sex† 160 (59.5) 321 (64.3) 0.185
Siblings, yes† 151 (56.1) 289 (57.9) 0.634
Previous wheezing episode† 25 (9.3) 83 (16.6) 0.005
Allergic disease family history† 2 (0.7) 8 (1.6) 0.316
Previous admission history† 53 (19.7) 145 (29.1) 0.005

Values are presented as mean or number (%). CRP: normal range, 0–0.5 mg/dL; lymphocyte: normal range, 20%–50%.

ICU, intensive care unit; CRP, C-reactive protein.

Student t-test.

Chi-square test.

The ratio of single infection to coinfection of respiratory viruses isolated for 768 hospitalized children with acute bronchiolitis

Variable Total (n) Single infection, n (%) Coinfection, n (%)
Adenovirus 139 16 (10.5) 123 (88.5)
Influenza A virus 16 6 (37.5) 10 (62.5)
Influenza B virus 9 3 (33.3) 6 (66.7)
Metapneumovirus 40 13 (32.5) 27 (67.5)
Respiratory syncytial virus A 252 95 (37.7) 157 (62.3)
Respiratory syncytial virus B 140 57 (40.7) 83 (59.3)
Parainfluenza 1 35 10 (28.6) 25 (71.4)
Parainfluenza 2 10 3 (30.4) 7 (70.0)
Parainfluenza 3 33 7 (21.2) 26 (78.8)
Parainfluenza 4 27 9 (33.3) 18 (66.7)
Human rhinovirus 257 53 (20.6) 204 (79.4)
Corona 229E virus 8 0 (0) 8 (100)
Corona NL63 virus 11 3 (27.3) 8 (72.3)
Corona OC43 virus 22 2 (9.1) 20 (90.9)
Enterovirus 60 2 (3.3) 58 (96.7)
Human bocavirus 96 12 (12.5) 84 (87.5)

Correlation of severity with coinfected viruses for 768 hospitalized children with acute bronchiolitis∗

Infection Coinfected viruses
ADV (n=139) hMPV (n=96) RSV A (n=252) RSV B (n=140) hRV (n=257) ETV (n=60) hBoV (n=96)
ADV - 0.239 (0.137) –0.133 (0.034)† 0.046 (0.589) –0.002 (0.975) 0.092 (0.484) 0.012 (0.907)
Flu A 0.103 (0.226) - 0.106 (0.094) 0.053 (0.532) 0.117 (0.061) 0.066 (0.614) 0.134 (0.195)
Flu B –0.100 (0.239) - –0.074 (0.245) - –0.085 (0.175) - –0.106 (0.306)
hMPV –0.004 (0.960) - 0.005 (0.940) - –0.081 (0.194) 0.053 (0.688) 0.092 (0.373)
RSV A –0.051 (0.550) 0.106 (0.516)   –0.057 (0.500) –0.042 (0.503) 0.073 (0.577) –0.027 (0.794)
RSV B 0.115 (0.176) - –0.050 (0.432) - 0.077 (0.216) –0.066 (0.615) –0.069 (0.507)
hRV 0.015 (0.863) 0.189 (0.242) –0.131 (0.038)† 0.011 (0.897)   0.195 (0.135) 0.190 (0.064)
PIV 1 –0.098 (0.252) - –0.082 (0.197) - 0.055 (0.378) 0.099 (0.452) 0.085 (0.411)
PIV 2 0.127 (0.136) - –0.023 (0.718) - 0.093 (0.136) 0.172 (0.189) 0.160 (0.118)
PIV 3 –0.070 (0.415) 0.280 (0.080) –0.023 (0.718) - 0.146 (0.019)‡ 0.152 (0.246) 0.053 (0.609)
PIV 4 –0.057 (0.512) - 0.015 (0.840) 0.068 (0.481) 0.016 (0.809) –0.029 (0.826) –0.114 (0.268)
ETV 0.132 (0.124) 0.271 (0.115) 0.121 (0.106) –0.010 (0.920) 0.164 (0.013)‡ - 0.170 (0.097)
hCoV 229E - - –0.031 (0.627) - –0.031 (0.624) –0.149 (0.257) -
hCoV NL63 –0.144 (0.093) –0.136 (0.437) –0.152 (0.042)† - –0.002 (0.981) - -
hCoV OC43 –0.047 (0.587) - –0.024 (0.700) –0.039 (0.651) 0.062 (0.322) - –0.106 (0.306)
hBoV –0.073 (0.397) 0.351 (0.038)‡ –0.034 (0.651) 0.078 (0.418) 0.063 (0.344) 0.035 (0.792) -

ADV, adenovirus; hMPV, human metapneumovirus; RSV, respiratory syncytial virus; hRV, human rhinovirus; ETV, enterovirus; hBoV, human bocavirus; Flu, influenza virus; PIV, parainfluenza virus; hCoV, human coronavirus.

Spearman correlation analysis and then chi-square test.

Negative correlation (reduced severity).

Positive correlation (elevated severity).