Seven days ago he started becoming ill in a home with 4-5 school age children. Those children could become symptomatic (contagious) within 2 days, infecting their schools. The students in those schools could start being contagious about the time he was admitted to hospital. This could blow up very quickly. It probably won't, but it could. If it does, there is no way to lock down the city. That will be it. Last week we could have shut down flights out of West Africa and not faced this prospect.