Relationships between A(H1N1)pdm09 influenza infection and infections with other respiratory viruses.
BACKGROUND
A(H1N1)pdm09, a new influenza pandemic virus emerged in 2009. The A(H1N1)pdm09 infection had several unique characteristics which included rapid transmissibility and high morbidity in obese individuals, pregnant women and individuals suffering from chronic diseases.


OBJECTIVE
To study the relationships between A(H1N1)pdm09 influenza infection and infections with other respiratory viruses such as respiratory syncytial virus (RSV), human metapneumo virus (hMPV), adenovirus and seasonal influenza.


METHODS
Samples (nasopharyngeal swabs or aspirates) collected between 2007 until 2012 from patients of various ages that were hospitalized due to respiratory virus infections were analyzed for the presence of various respiratory viruses, using qRT-PCR.


RESULTS
In 2009-2010, when the pandemic influenza A(H1N1)pdm09 first appeared, two major infection peaks were noted and individuals of various ages were infected. Following the decline of the A(H1N1)pdm09 virus infection, the percentages of patients infected with adenovirus and hMPV increased, while infection frequency with RSV B and with seasonal influenza virus decreased. Furthermore, RSV infections were delayed and very few percentages of patients were co-infected with more than one virus. Interestingly, the A(H1N1)pdm09 virus lost its dominancy when it reappeared in the winter of 2010-2011, and at this time, only the incidence of RSV infections was affected by the A(H1N1)pdm09 virus.


CONCLUSIONS
The A(H1N1)pdm09 virus had distinct effects on other respiratory viruses when it first appeared versus later, when it evolved from being a pandemic to a seasonal virus.
Central Virology Laboratory, Ministry of Health, Chaim Sheba Medical Center, Ramat-Gan, Israel; The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Tal
T
Meningher
Musa
M
Hindiyeh
Liora
L
Regev
Hilda
H
Sherbany
Ella
E
Mendelson
Michal
M
Mandelboim
D000256:Adenoviridae / Q000302:isolation & purification*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D008297:Male; D029121:Metapneumovirus / Q000302:isolation & purification*; D008875:Middle Aged; D009305:Nasopharynx / Q000821:virology; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D018113:Respiratory Syncytial Virus, Human / Q000302:isolation & purification*; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology; D014777:Virus Diseases / Q000453:epidemiology* / Q000821:virology; D055815:Young Adult
A(H1N1)pdm09 virus; human metapneumo virus; respiratory syncytial virus; respiratory viruses; seasonal influenza viruses