二次感染，用抗生素的量或时间过度，导致人体内的正常菌群失调，一些平时存在于人体内的正常菌群成为致病菌，从而引起感染的现象。
除非出现二次感染，通常唇疱疹会在10天内痊愈，并且不会留下疤痕。
Unless there is a secondary infection, cold sores usually clear up within 10 days, and do not leave a scar.
被损伤的免疫系统不能够抵御一般疾病的侵袭而使鸡只更易于感染或死于二次感染。
The damaged immune is much less capable of defending against usual disease challenges and the bird is more likely to suffer or die from any of a number of secondary infections.
早期迹象表明，在宿主已经患另一种感染时，这种病毒可能更容易作为二次感染入侵。
There are early Suggestions that the virus may be a secondary infection more likely to invade when hosts already are dealing with another infectious agent.
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