Study On HMPV's Molecular Etiology And Clinical Characteristics In Children With Respiratory Tract Infection In Kunming

ObjectiveTo investigate the infection rate, combined infection rate, the characteristic of molecular epidemiology and clinical feature of human metapneumovirus (hMPV) in children with respiratory tract infection in Kunming area and to supply the spectrum of etiology which would give basic data and research specimen for monitoring viruses' variation in future.MethodsAccording to the inclusion criterion, from September 2009 to September 2010,550 children who visited a doctor at first time and were diagnosed as respiratory infection were collected specimens and clinical materials in 6 hospitals in Kuming, hMPV and other common etiologies were detected by mutiple-PCR. One positive specimen of hMPV was randomized chosen to be purified and be detected the sequence comparing the result to hMPV's protein gene sequence of several plants in Genbank, building the stammbaum on the basis of fragment of F gene. SPSS11.5 statistic software package was used to analyze data.Results1. Mutiple-PCR was used to detect 21 etiologies of 550 specimens, The positive rate of hMpV was 5.3%.2. Among the 29 children whose nasal swab was detected with positive hMpV, there were 23 males,6 females.The ratio was 3.83:1. The age diatribution was main under 1-year-old, The epidemic season of hMpV is in the autum and the winter.3. Among the cases of positive hMpv infection,12 cases(41.38%) only got hMpV infection,17 cases got hMPV infection mixed with other etiology.The mixed pathogens were respiratory syncytial virus B(5/29), rhinovirus (5/29), respiratory syncytial virus(3/29), influenza A virus (3/29), haemophilus influenza (3/29), parainfluenza virus (1/29).4. The chief symptoms and signs of 29 cases who were infected by hMPV, all (100%)had cough, 18 (62%)had fever,6 (21%)had dirrhea21 (72%),had sputum 18(62%) had moist rale,7 (24%)hadrhonchi,10 (34%)had wheezing,7 had difficult breathing(23.9%),2 had cyanosis(6.9%).Among the 29 cases,there were 24 (82.8%) diagnosed as acute bronchpneumonia,2 (6.9%) diagnosed as acute upper respiratory tract infection,2 (6.9%) diagnosed as capillary bronchitis,1 (3.4%) diagnosed as wheezing bronchitis; the pure infecion and mixed infection of hMPV have not There was no significant difference in age, course of disease and clinical manifestation.5. According to the blood routine test,11 cases (38%)showed the decrease of white blood cell, 16 cases (55%) showed the increase of lymphocyte,4 cases (14%) showed the increase of white blood cell.6. Among the 29 cases,27 children (93%) had been given antibiotic before visiting hospital, and partial children had been given two kinds of antibiotic.7. Sequence analysis of gene showed that the hMPV virus strain had 92-95% similar with nucleotide of A genotype's virus strain.Conclusions1. The hMPV is one of the important etiology of children with acute respiratory infection, and the ratio of infection is 5.3% in children under 5-year-old in Kunming Area.2. The ratio of mixed infection with hMPV is 58.62% among 29 cases. The common mixed etiology are respiratory syncytial virus A, rhinovirus, respiratory syncytial virus B, streptococcus pneumoniae, influenza A virus, parainfluenza virus.3. In Kunming Area, hMPV infection usually occurres in children under 1-year-old, and in the season of autum and winter.4. The common symptoms of hMPV infection are cough, fever,wheezing, In the cases of only hMPV infection, the ratio of wheezing is 41.67%,92-95%sequence of hMPV gene is similar with necleotide of hMPV genotype, and 94-97% is similar with necleotide in Peking, Taiwan, Guangzhou.