The main purpose of the last line of the passage is to signal the reader that steps will follow.
In the first part of the passage, the author is giving some <em>background information</em> about the topic, which functions as an introduction to develop the main topic. The last sentence serves <em>to trigger</em> what the passage is actually concerned in, that is, the different ways in which contamination by this bacterium can be avoided. Thus, what the reader is expecting after the last line are some steps to follow.
1 : a secret look She took a sneak peek at the birthday presents hidden in the closet. 2 : a brief showing We saw a sneak peek of the movie that will be released next month. Good luck on your assignment bro ~ JyMarkus
