1.   Although most of the newer viruses arrive as e-mail attachments, viruses can come from any number of sources, including commercial, shrink-wrapped software.

2.   Authorities say her disease has progressed rapidly because the virus came from a man infected for a long time and has mutated into a form resistant to some medication.

3.   After it was suggested that the virus may have come from Lithuania, officials in the former Soviet satellite said they would launch an investigation.

4.   But every few decades, a radically different virus comes along, triggering a pandemic that can kill millions across the globe.

5.   But knowing the virus came from chimpanzees left two pressing questions.

6.   But the team was unable to establish where the virus came from nor can it explain why the virus suddenly appeared in horses in Australia.

7.   But the virus has already come back in the chickens there.

8.   But, Markowitz said, as soon they stopped, the virus came roaring back.

9.   Just because a virus comes from an animal does not mean that it is specially infectious.

10.   Nobody yet knows where the invading virus came from, as this is a devilishly difficult disease to track.