1. Incubation period – time that passes from the entry of the pathogen into the host to the onset of clinical symptoms of the disease. It is the time of active multiplying of the pathogen. Can vary from days to months or years.
2. Prodromal period – beginning of the first general clinical symptoms, non-specific for the disease, for example, weakness, fever, pain, lack of appetite, etc.
3. Period of illness – signs and symptoms of disease become most obvious and severe
4. Period of decline – the time of decreasing the number of pathogen particles and declining of infectious symptoms
5. Period of convalescence – the returning to normal functions, although there still can be some infectious particles that host might excrete in the environment, also sometimes there can be some permanent damage inflicted that body can not repair