来自《耶鲁大学开放课程：1600年后西方社会的流行病第7集第7集》

or the search for work, failed harvests.

而离开自家的土地
And these newcomers, in large numbers,

而那些大量的新移民
to use contemporary medical jargon,

用当代医学术语来说
were immunologically naive.

他们免疫力一片空白
That is, they were susceptible

也就是说他们易受感染
and added to the pool of susceptibles in urban centers.

然后又进入城市中易感染人群的行列
In every generation or so, urban centers,

在每一代人中在城市中
whose children had already suffered smallpox

若天花作为地方性儿童疾病肆虐
as an endemic childhood disease,

且当地儿童都已受过这种病的折磨
suffered major epidemics among

那么不仅是儿童还有青年人
not only children but young adults,

青少年以及老人
adolescents and older people.

都会遭受主要流行病的折磨