t%3D1425422075000%26v%3D2%26position%305%26china_variant%3DFalse&utm_medium=10today.0303&position= 5&part=sl&chi na_variant=Fal se> nytimes.com / MARY H. K. CHOI I was introduced to them at work, the same place where most of us worry about contracting respiratory viruses. I'd just landed a job in sunny Los An