Epidemiologie Grundlagen

Epidemiologie

• Definition: The science of disease distribution, causes, and prevention within a population. Derived from Greek roots: "epi" (upon), "demos" (people), and "logos" (study).
• Aims: Identifying disease causes, determining disease prevalence and severity in populations, evaluating preventative health strategies, and providing a basis for public health decisions.

Key Concepts

• Virulence: The ability of a pathogen to cause an infection.
• Pathogenicity: Microorganism's capacity to trigger a disease.
  • Obligate Pathogens: Always cause disease.
  • Facultative Pathogens: Can cause disease under specific conditions.
  • Apathalogenic pathogens: Do not cause disease.
• Host Range: A microorganism's preference for particular host species.
• Organotropism: A microorganism's preference for particular organs.
• Incidence: New cases of a disease within a specific time frame.
• Prevalence: Total cases of a disease in a given population.
  • Point Prevalence: Existing cases at a specific moment.
  • Period Prevalence: Existing cases over a specific time period.
• Mortality: Death rate in a population.
• Morbidity: Illness rate in a population.

Disease Types

• Endemic: Continuously present disease within a particular area.
• Epidemic: A sudden increase in the occurrence of a disease in a specific region.
• Pandemic: Worldwide spread of a disease.

Infection

• Definition: A microorganism's capability to multiply in host tissue, trigger an immune response, and possibly inflict tissue damage.
• Inflammation Indicators: Symptoms associated with immune system activation (e.g., heat, redness, swelling).

Types of Infections

• Endogenous Infection: Pathogens from body's own flora causing disease in an unusual location.
• Exogenous Infection: Pathogens that are introduced into the host from the outside environment.
• Horizontal Infection: Transmission between individuals of the same generation.
• Vertical Infection: Transmission from one generation to the next (e.g., mother to fetus).

Infection Course and Manifestations

• Course: The progression of an infection. Can be sudden and severe, slow and persistent, or intermittent.
  • Foudroyant ("thunderbolt"): Rapid, severe, and often fatal.
  • Acute: Abrupt onset with symptoms lasting a shorter duration.
  • Chronic: Slow onset with symptoms that persist longer.
  • Recurrent: Episodes of infection followed by periods with no symptoms.
• Manifestations: Symptoms exhibited during an infection.
  • Latent: Period without noticeable symptoms.
  • Silent (Inapparent): Infection present, but no noticeable symptoms.
  • Manifest/Obvios: Infection with noticeable symptoms.
  • Subclinical: Infection with mild symptoms that are not easily identified.

Colonization and Contamination

• Colonization: Pathogen establishment in the host without an overt immune response.
• Contamination: Pathogens present on surfaces without their proliferation or invasion of the tissue.

Incubation Period

• The time interval between pathogen exposure and the appearance of symptoms or disease manifestations.

Routes of Transmission

• Direct transmission: Close contact transmission of pathogens (e.g., droplet spread, touch)
• Indirect transmission: Transmission of pathogens via vehicles (e.g., contaminated food, water) or vectors (e.g., insects/arthropods).

Infection Targets

• Risk factors influencing susceptibility, including age, weakened immune systems, chronic conditions, medications, and nutritional state.

Prevention

• Primary prevention: Measures to prevent an infection before it occurs (e.g., vaccination, hygiene, personal protective equipment).
• Secondary prevention: Measures to detect infection early and intervene (e.g., screening, diagnostics).
• Tertiary prevention: Measures to reduce the impact and treat complications of infections (e.g., supportive care, rehabilitation).

Notifiable Diseases

• Diseases legally required to be reported to public health authorities.