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Swine flu case definition

The Health Protection Agency is using the following case definition for swine flu.

Clinical criteria

Any person with one of the following:

- Fever >38oC OR history of fever AND flu-like illness (two or more of the following symptoms: cough, headache, rhinorrhea or vomiting/diarrhoea)

- Other severe/life-threatening illness suggestive of an infectious process

Laboratory criteria

At least one of the following tests:

- Specific real-time RT-PCR swine influenza

- Four-fold rise in swine influenza A (H1N1) virus specific antibodies (acute phase sera and convalescent >10-14 days later)

Epidemiological criteria

At least one of the following in a person during the seven days before onset of illness:

- Close contact with a confirmed or probable case of swine flu A (H1N1) virus infection while the case-contact was ill or in the 24 hours before illness onset

- Travelled to a geographical area known to have confirmed or probable cases of swine influenza A/H1N1

Case classification:

A. Possible case

Any person meeting the clinical and epidemiological criteria

B. Probable case

Any person meeting the clinical and epidemiological criteria AND with a positive influenza A infection of an untypable type

C. Confirmed case

Any person with laboratory confirmation

D. Discarded case

Any suspect case not fulfilling the possible case definition or a possible case if the laboratory result is negative

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