title: [Eleven cases of co-infection with influenza type A and type B suspected by use of a rapid diagnostic kit and confirmed by RT-PCR and virus isolation].
abstract: In the 2004/05 influenza season there were epidemics of influenza caused by several types of viruses (type B and A (H3) viruses, and type B, A (H3), and A (H1) viruses) in many areas of Japan. In such epidemics a single individual could be co-infected with several influenza viruses. From February to March in 2005, we examined 15 patients who were positive for influenza type A and B viruses when tested with a rapid diagnostic kit. The type A (H3) and B influenza virus genes were successfully amplified by RT-PCR in 10 of the 15 patients, confirming that they were co-infected with type A (H3) and B viruses. The type A (H1) and B virus genes were successfully amplified in another patient, confirming that the patient was co-infected with type A (H1) and B viruses. By contrast, 2 patients were clearly positive for type A and B viruses according to the rapid diagnostic kit, but positive for type B virus alone by RT-PCR. No influenza virus genes were detected by RT-PCR in the remaining 2 patients. To isolate one type from a mixture of two different types of influenza viruses in a specimen, we neutralized one of the types with type-specific antiserum, and isolated the other with MDCK (+) cells. The results obtained by virus isolation were identical to those obtained by RT-PCR. Influenza viruses corresponding to the results of RT-PCR were isolated from 9 of the 11 patients in which isolation was attempted. No viruses were isolated from the 2 patients in whom no virus genes were detectable by RT-PCR. Based on these results we concluded that 11 of 15 patients who were positive for type A and B viruses according to the rapid diagnostic kit were co-infected with type A (H3) or A (H1) and B virus. When several types of influenza viruses are prevalent, as in the 2004/05 influenza season, the possibility of a patient being co-infected with more than one type of influenza virus should be considered.
authors.affiliation: Hiroshima Prefectural Institute of Health and Environment.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Takao
authors.forename: Michimaru
authors.initials: M
authors.lastname: Hara
authors.forename: Osamu
authors.initials: O
authors.lastname: Kakuta
authors.forename: Yukie
authors.initials: Y
authors.lastname: Shimazu
authors.forename: Masaru
authors.initials: M
authors.lastname: Kuwayama
authors.forename: Shinji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Kazuo
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000235:genetics / Q000302:isolation & purification*; D009981:Influenza B virus / Q000235:genetics / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology; D008297:Male; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D011933:Reagent Kits, Diagnostic