To clarify the epidemiology of enterovirus 68 (EV68), which is one of the most rarely identified enteroviruses, virus isolation and molecular screening using RT-PCR was performed on 6307 respiratory specimens collected at pediatric clinics in Yamagata, Japan between 2005 and 2010. In the years 2005-2009, 10, 1, 2, 0, and 2 (40) EV68-positive cases, respectively, were identified by RT-PCR. In 2010, 40 cases were identified altogether: 2 by isolation only, 26 by RT-PCR only, and 12 by both isolation and RT-PCR. Phylogenetic analysis indicated that plural genetically distinct clusters co-circulated. These results suggest that that difficulty in EV68 isolation leads to an underestimation of the prevalence of EV68 infections.
Human rhinovirus (HRV) C was recently identified as the third species of HRV using a molecular technique. Infections caused by previously identified HRVs (A and B) are thought to be limited to the respiratory tract; however, pathogenesis of HRVC is still largely unknown. A total of 816 nasopharyngeal swabs from hospitalized children with severe respiratory infections in the Philippines (May 2008–May 2009) were tested for HRV by reverse transcription polymerase chain reaction (RT-PCR), and 243 samples (29.8%) were positive for HRV. Among these patients, serum samples were also tested to determine whether specific HRV species were associated with viremia. Only 30 serum samples (12.3%) were positive for HRV. However, the HRV positive rates were different among HRV species, 3% (4/135) for HRVA, 0% (0/25) for HRVB, and 31% (26/83) for HRVC, and were the highest on 2 days after the onset of symptoms. These results suggest that HRVC may have a different pathogenicity and can more commonly cause viremia than HRVA and HRVB. Serum positive rates for HRV are affected by age, i.e., higher positive rates for those aged 1 year or more. HRVC that were detected from serum exhibited the same level of sequence diversity as those positive only for nasopharyngeal samples in phylogenetic analysis. However, all HRVA which were detected from serum were clustered in a monophyletic clade based on their 5′ non-coding region (NCR) sequences, which is closely related with a certain HRVC genotype (A2) in 5′-NCR. This finding suggests that the 5′NCR region may be associated with viremia.
BackgroundPneumonia remains a leading cause of child death in developing countries. The viruses in severe pneumonia remain poorly defined.MethodsThe study was conducted at the Eastern Visayas Regional Medical Center in Tacloban City, Philippines from May 2008 to May 2009. Patients aged 8 days to 13 years old who were admitted to the Department of Pediatrics with severe pneumonia were enrolled for the study. Upon admission, polymerase chain reaction was performed using nasopharyngeal swabs and blood cultures to detect respiratory viruses and bacteria, respectively.ResultAmong the 819 patients enrolled, at least one virus was detected in 501 cases (61.2%). In addition, 423 cases were positive for a single virus while bacteria were detected in the blood culture sample of 31 cases. The most commonly detected viruses were human rhinoviruses (n = 189), including types A (n = 103), B (n = 17), and C (n = 69), and respiratory syncytial virus (RSV) (n = 165). Novel viruses such as human metapneumovirus, human coronavirus NL63, human bocavirus, and human polyomaviruses WU and KI were also detected. There were 70 deaths, and one or more viruses were detected in 35 (50%) of these cases. Positivity only for influenza A virus (OR = 4.3, 95% CI = 1.3-14.6) was significantly associated with fatal outcome. From the blood culture, Burkholderia cepacia group (n = 9), Streptococcus pneumoniae (n = 4), Staphylococcus aureus (n = 4), Haemophilus influenzae (n = 1), and Salmonella C1 (n = 1) were also isolated.ConclusionViruses were commonly detected in children with severe pneumonia in the Philippines. Hence, viral etiologies should be considered while developing better effective strategies to reduce child pneumonia-related deaths in developing countries.
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