Diversity of respiratory viruses detected among hospitalized children with acute lower respiratory tract infections at Hospital Serdang, Malaysia.

BACKGROUND: The role of respiratory viruses as the major cause of acute lower respiratory tract infections (ALRTIs) in children is becoming increasingly evident due to the use of sensitive molecular detection methods. The aim of this study was to use conventional and molecular detection methods to assess the epidemiology of respiratory viral infections in children less than five years of age that were hospitalized with ALRTIs. METHODS: The cross-sectional study was designed to investigate the occurrence of respiratory viruses including respiratory syncytisl virus (RSV), human metapneumovirus (HMPV), influenza virus A and B (IFV-A and B), parainfluenzavirus 1, 2, 3 and 4 (PIV 1, 2, 3 and 4), human rhinoviruses (HRV), human enterovirus (HEV), human coronaviruses (HCoV) 229E and OC43, human bocavirus (HBoV) and human adenovirus (HAdV) in hospitalized children with ALRTIs, at Hospital Serdang, Malaysia, from June 16 to December 21, 2009. The study was also designed in part to assess the performance of the conventional methods against molecular methods. RESULTS: Viral pathogens were detected in 158 (95.8%) of the patients. Single virus infections were detected in 114 (67.9%) patients; 46 (27.9%) were co-infected with different viruses including double-virus infections in 37 (22.4%) and triple-virus infections in 9 (5.5%) cases. Approximately 70% of samples were found to be positive using conventional methods compared with 96% using molecular methods. A wide range of respiratory viruses were detected in the study. There was a high prevalence of RSV (50.3%) infections, particularly group B viruses. Other etiological agents including HAdV, HMPV, IFV-A, PIV 1-3, HBoV, HCoV-OC43 and HEV were detected in 14.5, 9.6, 9.1, 4.8, 3.6, 2.4 and 1.8 percent of the samples, respectively. CONCLUSION: Our results demonstrated the increased sensitivity of molecular detection methods compared with conventional methods for the diagnosis of ARTIs in hospitalized children. This is the first report of HMPV infections in Malaysia.

Biodiversity and clinico-demographic characteristics of human rhinoviruses from hospitalized children with acute lower respiratory tract infections in Malaysia.

BACKGROUND: There is accumulating evidence that human rhinovirus (HRV) causes acute lower respiratory tract infections (ALRTI). Recently, HRV-C was identified as a new species of HRV, but its spectrum of clinical disease is not well understood. OBJECTIVES: We investigated the molecular epidemiology, demographic and clinical characteristics of HRVs among hospitalized children with ALRIs. STUDY DESIGN: One hundred and sixty-five nasopharangeal aspirates taken from children <5 years hospitalized with ALRTIs in Serdang Hospital, Malaysia, were subject to reverse transcriptase-PCR for HRV. Phylogenetic analysis on VP4/VP2 and 5'-NCR regions was used to further characterize HRV. Other respiratory viruses were also investigated using semi-nested multiplex RT-PCR assay. Clinical parameters were analyzed between HRV, RSV and IFV-A mono-infections and between HRV species. RESULTS: HRV was detected in 54 (33%) patients for both single (36 samples) and multiple (18 samples) infections, 61.1% (22/36) represents HRV-A strains while the remaining 14 HRV-C. Strain P51 was the first reported representative of HRV98. The majority of the single HRV cases were in the second half of infancy; HRV-C occurred among older children compared with HRV-A. HRV children were admitted significantly earlier and less febrile than RSV and IFV-A infection. HRV-C infected children were more likely to have rhonchi and vomiting as compared to HRV-A. Pneumonia was the most common discharge diagnosis followed by bronchiolitis and post-viral wheeze in HRV patients. CONCLUSION: Our study showed high prevalence of HRVs and detection of HRV-C among hospitalized children with ALRTIs in Malaysia. Analysis of clinical parameters suggested specific features associated with HRVs infections and specific HRV groups.

Circulation of human respiratory syncytial virus strains among hospitalized children with acute lower respiratory infection in malaysia.

Human respiratory syncytial virus (RSV) is a major viral pathogen associated with acute lower respiratory tract infections (ALRTIs) among hospitalized children. In this study, the genetic diversity of the RSV strains was investigated among nasopharyngeal aspirates (NPA) taken from children less than 5 years of age hospitalized with ALRTIs in Hospital Serdang, Malaysia. A total of 165 NPA samples were tested for the presence of RSV and other respiratory viruses from June until December 2009. RSV was found positive in 83 (50%) of the samples using reverse transcription polymerase chain reaction (RT-PCR). Further classification of 67 RSV strains showed that subgroups A and B comprised 11/67 (16.4%) and 56/67 (83.6%) of the strains, respectively. The second hypervariable region at the carboxyl-terminal of the G gene was amplified and sequenced in order to do phylogenetic study. The phylogenetic relationships of the samples were determined separately for subgroups A and B using neighbor joining (NJ), maximum parsimony (MP), and Bayesian inference (BI). Phylogenetic analysis of the 32 sequenced samples showed that all 9 RSV-A strains were clustered within NA1 genotype while the remaining 23 strains of the RSV-B subgroup could be grouped into a clade consisted of strains with 60-nucleotide duplication region. They were further classified into newly discovered BA10 and BA9 genotypes. The present finding suggests the emergence of RSV genotypes of NA1 and BA. This is the first documentation of the phylogenetic relationship and genetic diversity of RSV strains among hospitalized children diagnosed with ALRTI in Serdang, Malaysia.