Influenza Viruses and RSV – a Leading Role in Acute Respiratory Infections During the 2015/2016 Season

Abstract from Fourth National Congress of Virology with International Participation /Days of Virology in Bulgaria Sofia, May 18th - 20th, 2016

Ivan Ivanov, Svetla Angelova, Irina Georgieva, Atanas Mangarov, Tatiana Tcherveniakova, Neli Korsun

Infectious hospital (SBALIPB) „Prof. Ivan Kirov”, Sofia;

Medical University, Sofia

National Reference Laboratory „Influenza and ARD”, NCIPD, Sofia, Bulgaria

Viral respiratory infections cause a huge number of diseases and hospitalizations among persons of all ages. The aim of this study was to analyze results of virological investigations and features in clinical course of infections with influenza viruses and respiratory-syncytial virus in hospitalized patients during the 2015/2016 season.

For the period from December 2015 to March 2016 a total of 197 clinical specimens (nasopharyngeal  swabs) of patients hospitalized in SBALIPB „Prof. Ivan Kirov”, Sofia were tested for influenza type A and type B viruses. All the patients had severe influenza-like symptoms and some of them developed complications. Detection and typing/ subtyping of influenza viruses were carried out using method Real Time RT-PCR. Specimens of children below 5 years of age were also tested for RSV usingvindividual Real Time RT-PCR reactions.

A total 80 (41%) specimens have tested positive for influenza viruses: 46 – positive for subtype A(H1N1)pdm09 virus, 24 positive for type B vius and 10 – positive for virus A(H3N2). Among 71 studied patients with CNS complications (oedema cerebri, meningitis, encephalitis, encephalopathy), A(H1N1)pmd09 virus was detected in 21 (30%) patients, and type B was detected in 14 (20%) patients.

Among 74 children tested for respiratory viruses, there were 17 (23%) positive for RSV. Most of them developed symptoms of infection of the lower respiratory tract. Clinical manifestations in patients with laboratory-confirmed viral infection were compared with those that were negative for respiratory viruses.

Conclusion: During the 2015/2016 season influenza A(H1N1)pmd09 and type B viruses were the predominant cause of severe or complicated respiratory diseases requiring hospitalization.

Among children below 5 years of age RSV was the main etiological agent, causing prolonged disease and slow recovery.