But the virus doesn't appear to notably sicken infected birds, unlike H5N1, another avian-flu virus that is deadly in birds and occasionally infects people.

WSJ: Bird Flu Found Outside China's Mainland

Previous research has shown that people infected with HSV-2 can pass the virus to someone else through genital contact even if they don't have symptoms.

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Just as the human immunodeficiency virus, or HIV, does in people, FIV works by wiping out infection-fighting T-cells.

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