症状与体征:潜伏期数小时至3天,常見1天。临床分4型,即隐性感染、輕型、典型型、重型。 1.隐性感染:可能病毒毒力、数量与机体免疫力接近平衡,病毒虽已侵入上呼吸道产生病变,但面积限局,程度輕微,未产生自觉与他觉症状。但呼吸道可以分离出病毒,血內特异抗体也增高,这类病人一般难以发現,所以不易估計发病数。 Symptoms and signs: the incubation period of several hours to 3 days, common 1 day. Clinical sub-4, that is, latent infection, light, typical, heavy. 1. Recessive infection: Probably the virus virulence, the number and the body immunity close to the balance, although the virus has invaded the upper respiratory tract lesions, but the area limits Bureau, to a lesser extent, did not produce consciousness and he felt symptoms. However, the respiratory tract can be isolated from the virus, blood-specific antibodies also increased, such patients are generally difficult to find, so it is not easy to estimate the incidence.