During the week, the U.S. military kept spraying the virus, from the length of spraying, temperature, wind direction, wind speed, air humidity, as well as infected with this bacteria soil, water bodies, and even crowds were recorded in relation to this experiment, due to the U.S. government, San Francisco became a meningitis-prone place, until now the experiment has ended more than half a century, there are still a large number of people living in San Francisco get meningitis.