The main purpose of the passage is to persuade people to alert people about the symptoms and treatments of avian flu.
Avian influenza is a bird flu which also infect humans. The flu infects humans by the feces and secretion or touching of eye, nose of the bird.
The passage is about the bird flu, the symptoms and the infection and how to protect from the disease.
Thus, the correct option is B) alert people about the symptoms and treatments of avian flu.
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