Once a new pathogen is introduced in one individual, it may spread to the larger population.

一旦一种新的致病源传播给一个个体，它可能向更多的人传播。

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Once a new pathogen is introduced in one individual, it may spread to the larger population.

一旦一种新的致病源传播给一个个体，它可能向更多的人传播。

youdao