METHODS: 2010-2015 incidence data for influenza A (IAV), influenza B (IBV), respiratory syncytial (RSV) and parainfluenza (PIV) virus infections were collected from 18 sites (14 countries), consisting of local (n = 6), regional (n = 9) and national (n = 3) laboratories using molecular diagnostic methods. Each site submitted monthly virus incidence data, together with details of their patient populations tested and diagnostic assays used.
RESULTS: For the Northern Hemisphere temperate countries, the IAV, IBV and RSV incidence peaks were 2-6 months out of phase with those in the Southern Hemisphere, with IAV having a sharp out-of-phase difference at 6 months, whereas IBV and RSV showed more variable out-of-phase differences of 2-6 months. The tropical sites Singapore and Kuala Lumpur showed fluctuating incidence of these viruses throughout the year, whereas subtropical sites such as Hong Kong, Brisbane and Sydney showed distinctive biannual peaks for IAV but not for RSV and PIV.
CONCLUSIONS: There was a notable pattern of synchrony of IAV, IBV and RSV incidence peaks globally, and within countries with multiple sampling sites (Canada, UK, Australia), despite significant distances between these sites.
METHODS: From October 2004 to May 2015, respiratory specimens were received from patients with respiratory tract infection suspicion. Influenza detection was carried out by either cell culture isolation, immunofluorescence or PCR-based assays. A RT-PCR was performed to distinguish both lineages by agarose gel electrophoresis. Whole genome amplification was performed using the universal primer set by Zhou et al. in 2012, and subsequently sequenced using Roche 454 GS Junior platform. Bioinformatic analysis was performed to characterise the sequences with B/Malaysia/2506/2007 and B/Florida/4/2006 corresponding sequences as reference of (B/VIC) and (B/YAM), respectively.
RESULTS: A total of 118 FLUBV (75 FLUBV/VIC and 43 FLUBV/YAM), from 2004 to 2006, 2008-2011 and 2012-2015 seasons, were studied. The whole genome of 58 FLUBV/VIC and 42 FLUBV/YAM viruses was successfully amplified. Based on HA sequences, most FLUBV/VIC viruses (37; 64%) belonged to clade 1A (B/Brisbane/60/2008) except to 11 (19%), which fell within clade 1B (B/HongKong/514/2009) and 10 (17%) to B/Malaysia/2506/2004. Nine (20%) FLUBV/YAM viruses belonged to clade 2 (B/Massachusetts/02/2012), 18 (42%) to clade 3 (B/Phuket/3073/2013) and 15 (38%) fell within Florida/4/2006. Numerous intra-lineage reassortments in PB2, PB1, NA and NS were found in 2 2010-2011 viruses. An important inter-lineage reassortment event from 2008 to 2009 (11), 2010-2011 (26) and 2012-2013 (3) FLUBV/VIC (clade 1) strains to FLUBV/YAM (clade 3) was found, in addition to 1 reassortant NS in 2010-2011 B/VIC virus.
CONCLUSIONS: Intra- and inter-lineage reassortment episodes were revealed by WGS. While PB2-PB1-HA remained in complex, NP and NS reassortant viruses were found in both lineages. Despite reassorment events are not often, the characterisation only by HA and NA sequences might be underestimating their detection.
METHODS: In this retrospective multicenter study conducted from 2016-2019, enrolled patients were divided into 2 treatment groups. Group 1 patients were started on Antiviral drug (oseltamivir) alone therapy. Group 2 patients were initiated on Antiviral drug (oseltamivir) in combination with Antibiotic therapy. Using acute respiratory illness scoring, symptom severity score was assessed daily for 8 symptoms namely, fever, fatigue, headache, cough, sore throat, wheezing, muscle ache and nasal congestion. For each symptom the severity was scored from scale 0-3. Results: Overall mean ARI severity score was statistically significantly lower (p less than 0.05) on day 2 (14.65-vs-13.68), day 3 (12.95-vs-11.67) and day 4 (10.31-vs-9.12 ) for influenza-A (non-H1N1) while day 3 (12.52-vs-11.87) and day 4 (11.21-vs-10.18) for influenza-B patients for patients who were initiated on oseltamivir-antibiotic combination therapy. Fever, cough and nasal congestion showed statistically significant improvement within 4 days of initiation of combination treatment. Fatigue, sore throat and muscle ache improvement pattern was same for both treatment protocols.
CONCLUSION: Oseltamivir-antibiotic combination treatment showed early resolution of some symptoms with cumulatively reduced mean symptom severity score in severe influenza infection hospitalized patients.
METHODOLOGY/PRINCIPAL FINDINGS: Sentinel and study sites collected nasopharyngeal specimens for diagnostic detection, virus isolation, antigenic characterization, sequencing and antiviral susceptibility analysis from patients who fulfilled case definitions for influenza-like illness, acute lower respiratory infections and event-based surveillance. Each year in Cambodia, influenza viruses were detected mainly from June to November, during the rainy season. Antigenic analysis show that A/H1N1pdm09 isolates belonged to the A/California/7/2009-like group. Circulating A/H3N2 strains were A/Brisbane/10/2007-like in 2009 before drifting to A/Perth/16/2009-like in 2010 and 2011. The Cambodian influenza B isolates from 2009 to 2011 all belonged to the B/Victoria lineage represented by the vaccine strains B/Brisbane/60/2008 and B/Malaysia/2506/2004. Sequences of the M2 gene obtained from representative 2009-2011 A/H3N2 and A/H1N1pdm09 strains all contained the S31N mutation associated with adamantanes resistance except for one A/H1N1pdm09 strain isolated in 2011 that lacked this mutation. No reduction in the susceptibility to neuraminidase inhibitors was observed among the influenza viruses circulating from 2009 to 2011. Phylogenetic analysis revealed that A/H3N2 strains clustered each year to a distinct group while most A/H1N1pdm09 isolates belonged to the S203T clade.
CONCLUSIONS/SIGNIFICANCE: In Cambodia, from 2009 to 2011, influenza activity occurred throughout the year with peak seasonality during the rainy season from June to November. Seasonal influenza epidemics were due to multiple genetically distinct viruses, even though all of the isolates were antigenically similar to the reference vaccine strains. The drug susceptibility profile of Cambodian influenza strains revealed that neuraminidase inhibitors would be the drug of choice for influenza treatment and chemoprophylaxis in Cambodia, as adamantanes are no longer expected to be effective.