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A 70-year-old man was being treated for asthma and chronic obstructive pulmonary disease, which had been well controlled. He was seen at our emergency outpatient department on October 24, 2009, for respiratory distress and mild fever. Point-of-care testing for influenza, general bacteria, and acid-fast bacilli in the sputum, were negative. With antibiotics ineffective, his respiratory status worsened, requiring him to be intubated and ventilated mechanically. Steroid pulse therapy temporarily improved his condition, as confirmed by imaging studies, but he died on hospital day 38. Polymerase chain reaction (PCR) analysis of tracheal secretion and bronchial washings collected on hospital day 14 and 21 were negative for influenza (H1N1) 2009 virus, which was identified in a subsequent culture. Negative results for reverse transcriptase-PCR analysis leave (H1N1) 2009 virus unable to be diagnosed clinically. Culture tests and repeated PCR analysis have been done in cases of strongly suspected clinical infection to confirm results. Our case, in which the virus was identified by culture, suggests that the viral load may have been too low or the time of culture inappropriate.

The epidemiologic features of respiratory syncytial virus (RSV) infection were investigated by detecting the virus in throat swab specimens from patients with acute respiratory symptoms attending the sentinel surveillance clinics in Yokohama City in 5 seasons from July 1998 to June 2003. Throughout the 5 seasons, RSV was found from 181 in 2683 specimens tested (6.7%) by virus isolation in cell culture or genome detection using nested RT-PCR, and this detection rate followed that of influenza virus (infl.v.) (441/2683; 16.4%), while the proportion of RSV isolates in a season fluctuated from 12 to 22% of all causative viruses identified. Analysis of monthly detected number of strains revealed that the peak of RSV isolation was present in December which preceded that of infl.v. by 2 months. Moreover, RSV strains were isolated sporadically during late spring to early autumn (from May to September) when infl.v. was scarcely detected. Among 181 RSV strains, 172 could be subgrouped; 104 were identified as subgroup A, while 68 were B. Subgroup A were detected more frequently throughout the 5 seasons (57%), though the proportion varied seasonally and subgroup B exceeded both in 2000/2001 and 2002/2003 seasons (61% and 70%, respectively). Clinical characteristics of RSV-infected patients were compared with those infected with infl.v. Age distribution of cases revealed that RSV detected predominantly (79%) from lower age groups (less than 5 years) compared to infl. v (41%). As for the proportion of cases showing clinical symptoms of lower respiratory inflammation predominated in RSV-infected irrespective of age groups.

We evaluated a flow-through immunoassay for rapid detection of influenza A and B viral antigens, RapidTesta FLU AB (Daiichi Pure Chemicals Co., Ltd., Tokyo, Japan), by using 507 specimens collected from patients with influenza-like symptoms during the 2002/2003 influenza season in Japan. The specimens consisted of 239 nasal swabs and 268 nasal aspirates; 374 specimens were collected from pediatric patients (under 16 years of age) and 133 from adult patients. RapidTesta FLU AB was compared with cell culture and nested reverse transcription-polymerase chain reaction (RT-PCR). Cell culture detected influenza virus from 66.7% of the 507 specimens (influenza AH3: 44.0%, B: 22.7%). For nasal swabs, it had a sensitivity of 81.9% (77/94), a specificity of 97.9% (142/145) and an efficiency of 91.6% (219/239) for influenza A virus as well as a sensitivity of 80.0% (52/65), a specificity of 98.3% (171/174) and an efficiency of 93.3% (223/239) for influenza B. For nasal aspirates, RapidTesta FLU AB had a sensitivity of 83.2% (109/131), a specificity of 98.5% (135/137) and an efficiency of 91.0% (244/268) for influenza A as well as a sensitivity of 82.7% (43/52), a specificity of 97.7% (211/216) and an efficiency of 94.8% (254/268) for influenza B. RapidTesta FLU AB is characterized by high specificity, low false positive rate, and 10-minute detection of influenza virus. These advantages suggest that RapidTesta FLU AB is a useful kit to assist physicians in making a diagnosis of influenza on candidates for antiviral therapy.

We evaluated the performance of an improved version of Espline Influenza A & B-N (Fujirebio Inc., Japan), an immunochromatography test using enzyme immunoassay for rapid diagnosis of influenza A and B. The test produced positive results for four strains of influenza viruses and thirty-one influenza viral antigens and negative results for all of thirty strains of other respiratory viruses that were tested. The detection limit of this test was 5.8 x 10(2) to 5.8 x 10(3) pfu/assay, which is more sensitive than the old version of Espline. Furthermore, 715 respiratory specimens collected from the patients (children, 79.4%; adults, 18.5%; unknown, 2.1%) with influenza-like illnesses during the 2002/2003 influenza season in Japan were tested as part of a clinical evaluation of this test. The relative performance of this test compared to cell culture and nested RT-PCR results were examined. In the cell cultures, influenza viruses were detected in 488 of the 715 specimens (overall, 68.3%; AH3, 41.7%; B, 26.4%; AH3 and B, 0.1%). For influenza A, the sensitivity of this test was 95.4% (125/131) for nasal aspirates, 96.8% (92/95) for nasal swabs, and 85.1% (63/74) for throat swabs. For influenza B, the sensitivity of this test was 91.2% (52/57) for nasal aspirates, 88.1% (59/67) for nasal swabs, and 71.6% (48/67) for throat swabs. The new test exhibited a remarkably higher sensitivity to influenza A in throat swabs than the old version of Espline. Only two false positive results were obtained out of a total of 223 virus negative specimens; the specificity of the test was 100% (88/88) for nasal aspirates, 97.6% (81/83) for nasal swabs, and 100% (52/52) for throat swabs. We conclude that the new Espline Influenza A&B-N rapid diagnostic test is easy to use and has a high sensitivity and specificity, especially for influenza A.

We carried out clinical and basic studies of the Directigen Lateral Flow RSV (Becton, Dickinson and Company, USA), a rapid test kit that detects respiratory syncytial virus (hereinafter referred to as "RSV") antigens based on immunochromatography. For the clinical study, 103 nasopharyngeal aspirates from patients with acute respiratory infections were used to evaluate the kit. Compared to the cell culture method, the Directigen Lateral Flow RSV showed a sensitivity of 100% (16/16) and a specificity of 94.3% (82/87), and an agreement rate of 95.1% (98/103). When compared to conventional testing kits, we found that the total agreement rate with the Directigen RS (Nippon Becton Dickinson and Company) was 88.3% (91/103) and with RSV TestPack (Dainabot Co., Ltd.) was 91.3% (94/103). The detection limit of the Directigen Lateral Flow RSV was 2 x 10(3) PFU/ml for both RSV subgroups A and B. In the crossreactivity test, only RSV was found positive. No other microorganisms were crossreactive. We also studied storage stability of nasopharyngeal aspirates and found that stability was not affected by storage at room and refrigerator temperatures for 14 days. Taken all together, the Directigen Lateral Flow RSV is useful for the diagnosis of RSV infection in a clinical setting because its performance is equivalent to conventional testing kits and is easy to use.