How many swine flu viruses are there?

现在有多少种猪流感病毒？

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Swine flu viruses that cause disease in pigs very rarely affect humans.

通常情况下，人类很少感染猪流感病毒。

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Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred.

一般来说猪流感并不会感染人类，但人们已经发现了少数人类感染猪流感的病例。

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People may contract swine flu by touching something with viruses on it and then touching their mouth or nose.

CNN: CDC confirms 7 cases of swine flu in humans

The children were infected with a virus known as swine influenza A H1N1, which has a unique combination of genes not previously seen in flu viruses in either humans or swine - although it shares similarities with a virus that has been circulating in pigs since 1999.

CNN: CDC: Swine flu seen in 2 California children

V. and Ebola viruses, in the nineteen-eighties, and the swine-flu scare a few years back.

NEWYORKER: Call the Doctor