The clinical spectrum of viral disease is wide, and because there is such variation, we will use the template of herpes viruses as an example. In general, viral infections are self-limited and usually produce long-term immunity, and secondary attacks by the same virus are uncommon.. Of the large number of herpes viruses, only eight infect humans. However, two general features of pathogens of these viruses are important. First, there must be close contact between infected and noninfected individuals for transmission to occur and no intermediate host is involved. Second, after the primary infection, herpes virus will persist in the host for life.