NEW YORK — The swine flu gave Wall Street a reason to turn cautious.

The Dow Jones industrial average gave up a midday recovery and retreated about 0.6 percent yesterday as the swine flu's death count in Mexico grew to about 150 people, from 100.

There have been far fewer cases reported elsewhere, including the United States, and no other fatalities. Investors were also mindful of previous health scares that had only short-term jostling effects on the market including bird flu, mad cow disease and the West Nile virus — none of which escalated into global pandemics.