1997: H5N1 hatched
Historically, human infections with bird flu were rare and caused only mild illness. The latest version of bird flu - called H5N1 - broke these rules when it first infected humans in Hong Kong in 1997. Eighteen people were infected and six of them died.
Patients suffered severe symptoms and, unlike other flu viruses, H5N1 caused viral pneumonia. The pneumonia did not respond to medication and was a speedy killer.
This was the first alarm bell to alert us to the pandemic potential of H5N1.
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| H5N1 is an unusually deadly flu virus. It causes viral pneumonia untreatable by antibiotics and often leads to a rapid death. |
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