Long-Term Shedding of Influenza Virus, Parainfluenza Virus, Respiratory Syncytial Virus and Nosocomial Epidemiology in Patients with Hematological Disorders

Abstract

Respiratory viruses are a cause of upper respiratory tract infections (URTI), but can be associated with severe lower respiratory tract infections (LRTI) in immunocompromised patients. The objective of this study was to investigate the genetic variability of influenza virus, parainfluenza virus and respiratory syncytial virus (RSV) and the duration of viral shedding in hematological patients. Nasopharyngeal swabs from hematological patients were screened for influenza, parainfluenza and RSV on admission as well as on development of respiratory symptoms. Consecutive swabs were collected until viral clearance. Out of 672 tested patients, a total of 111 patients (17%) were infected with one of the investigated viral agents: 40 with influenza, 13 with parainfluenza and 64 with RSV; six patients had influenza/RSV or parainfluenza/RSV co-infections. The majority of infected patients (n = 75/111) underwent stem cell transplantation (42 autologous, 48 allogeneic, 15 autologous and allogeneic). LRTI was observed in 48 patients, of whom 15 patients developed severe LRTI, and 13 patients with respiratory tract infection died. Phylogenetic analysis revealed a variety of influenza A(H1N1)pdm09, A(H3N2), influenza B, parainfluenza 3 and RSV A, B viruses. RSV A was detected in 54 patients, RSV B in ten patients. The newly emerging RSV A genotype ON1 predominated in the study cohort and was found in 48 (75%) of 64 RSV-infected patients. Furthermore, two distinct clusters were detected for RSV A genotype ON1, identical RSV G gene sequences in these patients are consistent with nosocomial transmission. Long-term viral shedding for more than 30 days was significantly associated with prior allogeneic transplantation (p = 0.01) and was most pronounced in patients with RSV infection (n = 16) with a median duration of viral shedding for 80 days (range 35-334 days). Long-term shedding of respiratory viruses might be a catalyzer of nosocomial transmission and must be considered for efficient infection control in immunocompromised patients.

Fig 1. Cases of influenza virus, parainfluenza virus and RSV infections in the hematology unit during the winter of 2012/2013 by week of laboratory confirmation.

Fig 2. Phylogenetic tree of influenza A(H3N2) (A) (nt78-nt1061) and B/Yamagata-lineage (B) (nt100-nt571) virus sequences of the HA gene was constructed with MEGA version 5.2 using the neighbor joining method.

Patient numbers are indicated, reference sequences for infuenza virus selected from GISAID are indicated by their accession numbers. Additionally, HA sequences from german national influenza sentinel are presented. The federal states are abbreviated as follows: Bayern (BAY), Baden-Württemberg (BWB), Berlin (BLN), Brandenburg (BBG), Bremen (BRE), Hamburg (HAM), Hesse (HES), Mecklenburg-Western Pomerania (MVP), Lower Saxony (NSA), North Rhine-Westphalia (NRW), Rhineland-Palatinate (RPF), Saarland (SAL), Saxony (SAS), Saxony-Anhalt (SAT), Schleswig-Holstein (SHO), Thuringia (THR). Bootstrap values greater than 70 are displayed on branch nodes.

Fig 3. Phylogenetic tree of parainfluenza virus sequences from the fusion gene was constructed with MEGA version 5.05 using the maximum likelihood method.

Patient numbers are indicated, reference sequences for parainfluenza virus type 3 selected from GenBank are indicated by their accession numbers. Bar indicates 0.1 nucleotide substitutions per site. Bootstrap values greater than 60 are displayed on branch nodes. Patient numbers of long-term virus shedding patients are indicated in bold.

Fig 4. Phylogenetic trees of RSV A (A) and RSV B (B) virus sequences from the second hypervariable region of the attachment protein G gene were constructed with MEGA version 5.05 using the maximum likelihood method.

Patient numbers are indicated, reference sequences for RSV A and RSV B selected from GenBank are indicated by their accession numbers. Bar indicates 0.1 nucleotide substitutions per site. Bootstrap values greater than 60 are displayed on branch nodes. Long-term RSV shedding patients are marked with a black dot.

Fig 5. Duration of influenza virus, parainfluenza virus and RSV shedding periods.