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Association between nasopharyngeal load of Streptococcus pneumoniae, viral co-infection and radiologically confirmed pneumonia in Vietnamese children.

Results from 75,000 geo-referenced households in Vietnam during two dengue epidemics reveal that human population densities typical of villages are most prone to dengue outbreaks; rural areas may contribute as much to dissemination of dengue fever as do cities.

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We hypothesized that host antiviral genes induced by type I interferons might affect the natural course of severe acute respiratory syndrome (SARS). We analyzed single nucleotide polymorphisms (SNPs) of 2',5'-oligoadenylate synthetase 1 (OAS-1), myxovirus resistance-A (MxA), and double-stranded RNA-dependent protein kinase in 44 Vietnamese SARS patients with 103 controls. The G-allele of non-synonymous A/G SNP in exon 3 of OAS-1 gene showed association with SARS (p=0.0090). The G-allele in exon 3 of OAS-1 and the one in exon 6 were in strong linkage disequilibrium and both of them were associated with SARS infection. The GG genotype and G-allele of G/T SNP at position -88 in the MxA gene promoter were found more frequently in hypoxemic group than in non-hypoxemic group of SARS (p=0.0195). Our findings suggest that polymorphisms of two IFN-inducible genes OAS-1 and MxA might affect susceptibility to the disease and progression of SARS at each level.

We have hypothesized that genetic predisposition influences the progression of SARS. Angiotensin converting enzyme (ACE1) insertion/deletion (I/D) polymorphism was previously reported to show association with the adult respiratory distress syndrome, which is also thought to play a key role in damaging the lung tissues in SARS cases. This time, the polymorphism was genotyped in 44 Vietnamese SARS cases, with 103 healthy controls who had had a contact with the SARS patients and 50 controls without any contact history. SARS cases were divided into either non-hypoxemic or hypoxemic groups. Despite the small sample size, the frequency of the D allele was significantly higher in the hypoxemic group than in the non-hypoxemic group (p=0.013), whereas there was no significant difference between the SARS cases and controls, irrespective of a contact history. ACE1 might be one of the candidate genes that influence the progression of pneumonia in SARS.

Hospitalized Vietnamese children with acute respiratory infection (ARI) were investigated for 13 viral pathogens using multiplex-polymerase chain reaction. We enrolled 958 children of whom 659(69%) had documented viral infection: rhinovirus (28%), respiratory syncytial virus (23%), influenza virus (15%), adenovirus (5%), human metapneumo virus (4.5%), parainfluenza virus (5%) and bocavirus (2%). These Vietnamese children had a range of respiratory viruses which underscores the need for enhanced ARI surveillance in tropical developing countries. Positive templates were used in each assay for quality control. RESULTSDuring the 14-months study period, a total of 1,014 pediatric patients from the catchment area were admitted to KHGH, of which 958 (95%) were enrolled in the study.Males comprised 58% of patients and 94% of the patients were less than 5 years old (median age: 1.4 years). The results showed that one or more respiratory viruses were found in 69% of patients: 11% had dual and 1.4% had triple infection. Eighty six percent of the viral ARI patients were less than 3 years old (detail information of age breakdown is shown in supplementary table 2, online only).Major viruses detected were rhinovirus (28%), RSV (23%) and influenza A (15%). This was followed by adenovirus (5%), hMPV (5%), PIV3 (4%) and bocavirus (2%). Other viruses (PIV1, PIV2 and influenza B) were detected in a small proportion (1.5%) of ARI patients. Across age, sex, and case categories, there were no significant differences between proportion of virus positive and negative patients.The pattern of virus detection did not differ between URTI and LRTI patients. A total of 268 radiologically-confirmed pneumonia (RCP) patients and 195 bronchiolitis 7 patients were identified. PIV3 detection was significantly associated with hospitalized LRTI (p=0.016) and bronchiolitis (p=<0.001). Similar to previous reports, we found that RSV infection was significantly associated with bronchiolitis (p=0.002) (6). We also found that a significantly higher proportion of patients (n=119)

Although a isoniazid preventive therapy programme was shown to be feasible, further adjustments on the selection of participants, enrollment process, and follow-up system based on these findings are necessary to increase the adherence.