natural infestation的用法和样例：
例句
- This is the first report of the presence of FMDV in bull semen due to natural infection in China.
这也是我国首次证实自然感染牛的精液被口蹄疫病毒污染。 - Because natural rotavirus infection was not associated with intussusception, they reasoned their vaccine would similarly not increase the risk of this complication.
由于自然感染轮状病毒并不会造成肠套叠，因此他们认为新疫苗也不会增加这种并发症的风险。
