L4.3: Natural History and Spectrum

• ● Natural History of Disease

  ○ The sequence of events pertaining to the progression of a disease process

  ○ In the absence of treatment

  ○ Natural = no intervention
• Four Important Stages

  1. Stage of Susceptibility

  2. Stage of Subclinical Disease

  3. Stage of Clinical Disease

  4. Stage of Recovery, Disability, or Death
• 1. Stage of Susceptibility

  ● During this stage, an individual becomes more prone to develop a disease brought about by various factors and mainly due to a higher rate of exposure from the pathogen.

  ● To limit exposure.

  ● Susceptibility due to exposure.
• 2. Stage of Subclinical Disease

  ● As the disease progresses comes its influence in the physiological activities of the individual’s body without him/her being aware of them during this time, pathologic changes already develop.

  ● Disease is asymptomatic during this stage.

  ● Without the person knowing

  a. Incubation Period

  ● Extends from the time of exposure to onset of diseases symptoms for infectious diseases.

  b. Latency Period — CHRONIC LIKE HIV

  ● Extends from the time of exposure to onset of disease symptoms for chronic diseases.
• 3. Stage of Clinical Disease

  ● Diagnoses being made to validate existence of abnormality

  ● May differ in terms of severity

  ● Spectrum of Disease

  ○ A range as to the effect of disease process in an individual

  ○ How severe is the disease

  ○ From mild to severe or fatal
• 3. Stage of Clinical Disease

  a. Infectivity

  ● Proportion of exposed persons who became infected

  b. Pathogenicity

  ● Infected individuals who develop clinically apparent disease

  c. Virulence

  ● Clinically apparent cases that are severe or fatal
• 4. Stage of Recovery, Disability, or Death

  ● End result of experiencing the disease whether he/she recuperates from the condition or it will worsen

  ● May lead to irreversible complications or end of life of an individual