Infektionsdosis (ID₅₀): Definition, Determinanten und Beispiele

Definition

The infectious dose (ID₅₀) is the number of pathogen units required to infect 50% of exposed susceptible hosts. It is a population-level statistical measure, not a fixed threshold for individuals.

Key Determinants

• Pathogen factors: Virulence genes, adhesion, immune evasion, inoculum phenotype.
• Route of exposure: Inhalation < ingestion < percutaneous < mucous membrane (generally).
• Host factors: Age, immunity (innate/adaptive), microbiome, genetics, nutrition, comorbidities.
• Environmental: Temperature, humidity, UV, vehicle (food/water matrix).

Illustrative Examples (Approximate Human ID₅₀)

Significance

Low ID₅₀ → high transmissibility, stringent infection control. Informs risk assessment, vaccine challenge studies, and biodefense planning.