Epidemiology of influenza B/Yamagata and B/Victoria lineages in South Africa, 2005-2014

Abstract

BackgroundStudies describing the epidemiology of influenza B lineages in South Africa are lacking.MethodsWe conducted a prospective study to describe the circulation of influenza B/Victoria and B/Yamagata lineages among patients of all ages enrolled in South Africa through three respiratory illness surveillance systems between 2005 and 2014: (i) the Viral Watch (VW) program enrolled outpatients with influenza-like illness (ILI) from private healthcare facilities during 2005–2014; (ii) the influenza-like illnesses program enrolled outpatients in public healthcare clinics (ILI/PHC) during 2012–2014; and (iii) the severe acute respiratory illnesses (SARI) program enrolled inpatients from public hospitals during 2009–2014. Influenza B viruses were detected by virus isolation during 2005 to 2009 and by real-time reverse transcription polymerase chain reaction from 2009–2014. Clinical and epidemiological characteristics of patients hospitalized with SARI and infected with different influenza B lineages were also compared using unconditional logistic regression.ResultsInfluenza viruses were detected in 22% (8,706/39,804) of specimens from patients with ILI or SARI during 2005–2014, of which 24% (2,087) were positive for influenza B. Influenza B viruses predominated in all three surveillance systems in 2010. B/Victoria predominated prior to 2011 (except 2008) whereas B/Yamagata predominated thereafter (except 2012). B lineages co-circulated in all seasons, except in 2013 and 2014 for SARI and ILI/PHC surveillance. Among influenza B-positive SARI cases, the detection of influenza B/Yamagata compared to influenza B/Victoria was significantly higher in individuals aged 45–64 years (adjusted odds ratio [aOR]: 4.2; 95% confidence interval [CI]: 1.1–16.5) and ≥65 years (aOR: 12.2; 95% CI: 2.3–64.4) compared to children aged 0–4 years, but was significantly lower in HIV-infected patients (aOR: 0.4; 95% CI: 0.2–0.9).ConclusionB lineages co-circulated in most seasons except in 2013 and 2014. Hospitalized SARI cases display differential susceptibility for the two influenza B lineages, with B/Victoria being more prevalent among children and HIV-infected persons.

Comparative global epidemiology of influenza, respiratory syncytial and parainfluenza viruses, 2010–2015

“…Despite multiple single-site or national surveillance data for influenza and/or RSV being available either via publication or online, e.g. from Argentina, 9 Brazil, 10 Canada, 11 UK, 12 The Netherlands, 13 Finland, 14 Bulgaria, 15 Russia, 16 South Africa, 17 Rwanda, 18 Madagascar, 19 Cambodia, 20 Thailand, 21 Malaysia, 22 Singapore, 23 The Philippines, 24 Indonesia, 25 Hong Kong, 26 Mongolia, 27 Japan, 28 Australia, 29 and New Zealand, 30 there are still relatively few global-scale studies that compare the contemporaneous (i.e. over the same time period) incidence patterns of common respiratory viruses across different countries -and nearly all of these used mostly publicly available surveillance data extracted from national surveillance websites, or published studies.…”

Influenza B viral load analysis in patients with acute respiratory infection from a tertiary hospital in Brazil

“…with 5 to 18 years 17. Statistically significant differences were not observed between the mean values of VL for the different analyzed groups, possibly due to the fact that inpatients have not presented a higher replication level than outpatients.…”

Decline in respiratory deaths not associated with influenza in Russia: effect of the introduction of the pneumococcal conjugate vaccine (PCV13), or improvement in care?

“…In particular, influenza B is characterized by the circulation of B/Yamagata and B/Victoria viruses. It is known that the age distribution for the B/Yamagata infections is notably older than for the B/Victoria infections [13,14].…”