Virulentní

Virulentní is a Czech adjective meaning highly virulent, capable of causing severe disease or rapid progression. In biology and medicine, virulence describes the degree of harm a pathogen can inflict on its host. The term is used for bacteria, viruses, fungi, and other organisms; the corresponding noun is virulence, and the adjective in Czech is virulentní.

Virulence is distinct from pathogenicity. Pathogenicity is the ability to cause disease in general, while virulence refers to the severity of disease once infection occurs. A pathogen may be pathogenic without being highly virulent, and virulence can vary among strains or hosts. Virulence factors are molecules or structures produced by pathogens that contribute to disease, such as toxins, capsules, invasion proteins, adhesins, and immune evasion mechanisms.

Measurement and context: virulence is often assessed through metrics like infectious dose, LD50, or case fatality rate, usually based on experimental data or epidemiological observations. Observed virulence is influenced by host factors (age, genetics, immune status) and exposure dose. The same organism can be virulent in one host or environment and less so in another.

In usage, virulentní describes strains or agents with high virulence; a non-virulent or avirulent strain lacks these properties. The concept is central in clinical microbiology, epidemiology, and plant pathology, guiding risk assessment and control strategies.