More evidence of False Negative as H1N1 hits Tokyo

[Skatman]

Japan's swine flu epidemic spread to the capital Tokyo as a 16-year-old high school girl there tested positive for the virus on Wednesday with the country's confirmed cases topping 250, officials said.

The girl, who lives in the western suburb of Hachioji, returned home from an eight-day trip to the US city of New York with her schoolmates on Tuesday and was cleared by a test at Tokyo's Narita airport, officials said.

Tokyo has almost 36 million people and is the world's most populous urban area. Experts had predicted it was only a matter of time before the flu hit the capital area.

"The student developed a fever while in flight from New York but she tested negative in rapid flu tests at Narita," Hideo Maeda, secretary of the city's welfare and health department said.

"She is hospitalised in Hachioji and has a fever, cough and a sore throat. But she is recovering well," Maeda told a news conference.

The health ministry said that the number of (A)H1N1 virus infections in Japan rose to 251, excluding the Tokyo case, as of late Wednesday.

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[Giuseppe]

Re: More evidence of False Negative as H1N1 hits Tokyo

From MMWR Early Release:

As of May 15, 2009, 9% of approximately 11,600 clinical specimens submitted for testing to California public health laboratories since April 27, 2009, were positive by rRT-PCR for influenza A; of those, 23% and 28% were subtyped as seasonal influenza A/H1 and A/H3, respectively. These results indicate that seasonal influenza viruses continue to circulate throughout California and might be a cause of influenza-like illness and positive results from rapid antigen tests.

Although rapid antigen test results were positive in 67% of tested cases in this series, anecdotal reports from other cases confirmed at CDPH VRDL, tested mostly in the outpatient setting, suggest that false positive and negative results are common.

Accordingly, CDPH has emphasized the importance of testing influenza viruses in the state with rRT-PCR. CDPH also has advised clinicians in California to collect respiratory specimens for rRT-PCR testing, subtyping, and further characterization at public health laboratories from patients who are hospitalized or who die with febrile respiratory illness.

Additional information regarding California testing guidelines is available at http://ww2.cdph.ca.gov/programs/vrdl/pages/diagnostictestingforswineinfluenzaA(H1).aspx.