十三个都是最近参加了同一个学校的墨西哥旅游活动。这个学校是在南卡罗来纳州的Newberry（参考资料：四月三十日南卡罗来纳州健康和环境控制局的官网信息）。

南卡罗来纳州健康和环境控制局的官网：http://www.scdhec.gov/flu/swine-flu.htm

Lab results released April 30 showed that 13 South Carolinians definitely have the swine flu virus. The lab results were announced by the U.S. Centers for Disease Control and Prevention (CDC).

View DHEC's latest press release on the lab results.

The 13 people who have the virus are all associated in some way with a recent school trip to Mexico. The trip was sponsored by an independent school in Newberry. Jerry Gibson, M.D., chief of DHEC’s Bureau of Disease Control, said they have been asked to voluntarily isolate themselves for a short time. Anyone who was exposed to them is asked to voluntarily quarantine themselves at home. Those in isolation will receive appropriate care, Gibson said.