传染力

In areas with high HBV endemicity, perinatal transmission is the main route of transmission, whereas in areas with low HBV endemicity, sexual contact amongst high-risk adults is the predominant route.

在HBV的高毒力区内，围产期是最主要的感染途径，而在低HBV毒力的地区，高危人群之间的性是传染的主要传播途径。

The causative agent of the disease is an Corona virus, infectious bronchitis virus IBV）, classified as Corona .Present vaccines for IB are all modified live viruses derived either by sequential passage embrocated chicken eggs. As Immunogenicity of IBV is usually correlated with its virulence, almost all modified live IB vaccines remained insufficient attenuation and have shown a variety of side effects including spread of vaccine virus to no vaccinates, occurrence of long term "carrier" birds, and increasing virulence during in vivo passage.

目前国内外预防本病所用的疫苗大多数是弱毒疫苗，但现用弱毒疫苗都存在以下缺点：（1）与IBV强毒一样，其弱毒疫苗株也能引起潜伏感染，潜伏感染的鸡将终生带毒；（2）疫苗病毒可以由接种鸡传染给非接种鸡，在鸡群之间传播过程中毒力会返强，从而成为新的感染源；（3）传染性支气管炎病毒极易发生变异，且易成为病毒重组的供体和受体，给使用IB传统疫苗预防和根除IB带来极大的困难。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。