Final answer:
Acute diseases have a rapid onset and short duration, including periods of illness and decline, which differ in pathogen quantity. An acute illness can exacerbate an existing chronic condition or be a separate health issue, and may possibly worsen symptoms depending on the individual's health.
Step-by-step explanation:
Acute diseases are characterized by a rapid onset and a relatively short duration. They can be distinguished from chronic diseases, which persist over a longer period of time. During an acute illness, there are typically two key phases: the period of illness and the period of decline.
The period of illness and the period of decline in an acute disease share the similarity of being stages in the disease process where significant symptoms may be present. However, they differ in the quantity of pathogen present within the host; generally, the period of illness sees a peak in pathogen levels, while the period of decline is characterized by a reduction in the pathogen's presence. This reduction marks the transition to the period of decline, typically initiated by an effective immune response or through medical intervention.
In the context of chronic diseases, an acute illness could either signify an exacerbation of the underlying chronic condition or represent a new, separate health issue. If the immune system is compromised by the chronic condition, the acute illness could indeed worsen symptoms or further compromise health. Vice versa, an acute illness has the potential to exacerbate the existing chronic condition, depending on the individual's overall health status and the nature of both the acute and chronic conditions.