感染病例数的英文：
flu caseload

Flu raged throughout the city.
流行性感冒风行全市。

The risk of a swine flu pandemic?
有猪流感疫情风险？

There is a lot of flu about.
这一带流感肆虐。

He was stuck at home with flu.
感冒把他困在了家中。

A flu epidemic is sweeping through the continent.
流感正在这个大陆上迅速蔓延。