1.   Amid a Darwinian struggle for survival, the microbes perform two major functions for their human hosts.

2.   And a worm, the Guinea worm, that enters a wound on the foot and grows as long as the leg of its human host.

3.   A. Because before our findings were published, the medical community always believed cholera was transmitted person to person, that it had a human host or reservoir.

4.   After repeated cycling through human hosts, a strongly transmissible strain could develop.

5.   Genetic modification could, in theory, render these organs and cells immunologically compatible with their human hosts.

6.   In the cultural universe, on the other hand, meme selection is partly guided by the human host.

7.   Influenza A viruses are notoriously unstable and wreak the most havoc on their human hosts.

8.   It is also possible that the implanted monkey immune system would attack the human host.

9.   It seems that the dead man has the demonic power to slip from one human host to another, as if life were a haunted football game.

10.   Larvae produced by adult worms migrate in the skin of human hosts, causing lesions and blindness when they reach the eyes.