Influenza viruses may co-circulate
Myers CA. Am J Trop Med Hyg. 2011;85:961-963.
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Secondary case patients of an index patient with influenza A/H1N1 were found to be coinfected with strains of influenza A/H1N1 and A/H3N2 that were closely related to existing strains, according to a recent report.
The researchers recounted the path of novel influenza A/H1N1 from its emergence in Mexico in early 2009 to a 23-year-old patient in central Cambodia who was diagnosed with pH1N1 in October of that year. Three children who resided in his home and the teacher of the children then developed a cluster of influenza-like illnesses.
Results of a genetic analysis using reverse transcriptase polymerase chain reaction electrospray ionization mass spectrometry indicated that two of the secondary case patients were coinfected with influenza A/H3N2 and pH1N1. It was further determined via phylogenetic analysis of the hemagglutinin genes from these isolated viruses that the strains were closely related to existing pH1N1 and A/H3N2 viruses circulating in the region, according to the results.
Patrick J. Blair, PhD, of the department of respiratory diseases at the Naval Health Research Center in San Diego, told Infectious Diseases in Children that the incident may be cause for further attention to be paid to co-circulating influenza viruses. The concern is that an easily transmissible and highly lethal influenza could result in a novel virus and increase the risk of pandemic, Blair said.
According to the researchers, genetic recombination was not evident within plaque-purified viral isolates on full-genome sequencing, and dual influenza infections may reassert in areas where they are co-circulating. They said the risk for zoonotic and seasonal influenza viruses is suggested in this incident.
The manuscript mentions (but does not document) the potential risk of recombination between A/H5N1 when they coinfect a susceptible host such as swine or humans, Blair said.
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