We are not seeing the factors that were associated with other H1N1 viruses, " Besser said.

我们没有看到和其他H1N1型流感病毒有关的因素。

Dr Besser said more information was needed to determine the extent of the threat posed by the virus.

贝丝医生说，还需要更多信息来确定此病毒引发的威胁的程度。

To be declared a pandemic, Besser said, the virus must be new, cause severe disease, and transmit easily enough to be sustained.

贝瑟说，只有病毒是新型病毒，病情严重，其传播速度保持在较快水平上，才能宣布为进入爆发流行状态。

CDC has tested 14 samples of the virus from Mexico and found seven were identical to the virus found in the U.S. cases, Besser said.

中心对来自墨西哥的14个样本进行了检测，结果发现有7个与美国发现的病毒一样。

Richard Besser, acting director of the U. S. Centers for disease Control and Prevention, said that over time 'more severe' cases of disease are likely to surface.

美国疾病控制预防中心代理主任贝瑟(richard Besser)说，随着时间的推移，将会出现更严重的病例。