Study On Human Bocavirus Infectionin Children Under Five Years With Respiratory Tract Infection In Kunming

Objective:To investigate the infection prevalence of human Bocavirus in children under five years with respiratory tract infection in Kunming, to explore main clinical features andpossible factors with acute wheezing, and to afford the pathogen evidence guiding clinical work.Methods:From October 2009 to December 2010,550 nasal swab samples were collected from sick children with acute respiratory tract infection multiplex polymerase chain reaction(MPCR) method was selected to test for Human Bocavirus(HBoV)and other 15 viruses and 6 bacteria of respiratory infection.The 15 viruses included Adenovirus A/B/C/D/E, human metapneumo virus. Human Coronavirus 229E/NL63, Human Coronavirus OC43/HKU1, Parainfluenza virus 1, Parainfluenza virus 2, Parainfluenza virus 3, Parainfluenza virus 4, Influenza A viruses, Influenza virus, Respiratory syncytial virus A, Respiratory syncytial virus B, Rhinovirus A B/C, Human Boca virus 1/2/3/4, Intestinal virus. The 6 species of bacteria included Streptococcus pneumoniae, Haemophilus influenzae, Bordetella pertussis, Legionella pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae. PCR products of HBoV VP1 from patients were randomly selected for sequencing analysis,. The sequences of the nucleotides and deduced amino acids were compared with those in the GenBank.Results:1 Among 550 nasal swab samples, there were 462(84%) samples which were found at least one bacteria or one virus. There were 18 (3.3%)samples positived for HBoV among all the swab samples.174 (90.6%)samples were found at least one pathogen positive among 192 nasal swab samples which were collected from children with wheezing symptom.There were 10 HBoV positive samples in 192 samples(5.2%).2 72%(13/18) children who were infected by HBoV were mainly under lyears(8 months to 1 years).3 There were 342 males among all the patients.18 samples positived for HBoV included 13males and 5 females.The patients who were infected by HBoV were also major in males.4 we found thet all the positive HBoV samples were collected from November to December. 5 Nearly all the patients(94%)who were infected by HBoV were found co-infection of the other pathogens. RSVA(38.9%),RSVB(38.9%),RV(38.9%),ADV(5.6%),PIV3(11.1%),FluA(11.1%),Haemophilus influenzae (16.7%),Streptococcus pneumoniae(10%).6 The patients who were infected by HBoV were diagnosed as acute bronchial pneumonia(12), acute bronchiolitis(3), asthmatic bronchitis(3).The main symptoms of HBoV infection were coughing, dyspnea and wheezing.7 Sequence analysis of these HBoV VP1 genes showed 98% homology to the registered sequence in GenBank.Conclusion:1 HBoV is an important pathogen of respiratory tract infection in children under 5 years.The Positive rate for HBoV detection was 3.3% among acute respiratory tract infection,5.2% among children with wheezing symptom.HBoV was mainly identified in patients with lower respiratory tract infection.2 The rate of co-infection is very high in the HBoV infection (94%).RSV is the most common co-infection pathogens with HBoV. The clinical symptoms of the samples only positived for HBoV was mild.3 HBoV is more epidemic during the winter (November to December). The infants look like infected more easily. The positive rate of male was higher than female patients.4 The major clinical features of HBoV infection are cough,dyspnea,wheezing, which is similar to Asthmatic bronchitis and Acute bronchial pneumonia.