Pathogen

Slovak term: Slovenský termín

1. Any micro-organisms which by direct interaction with (infection of) another organism cause disease in that organism (WHO 2006).
2. Any virus, microorganism or other substance causing disease (Stedman's Medical Dictionary 2006).
3. An agent of disease (WHO 2009)
4. See also [Infectious disease]

Explanation

The strict definition of a pathogen excludes those micro-organisms that cause disease indirectly by the synthesis of a toxin that may subsequently be ingested by the victim. Several microorganisms implicated in food poisoning cause disease in this way: Clostridium perfringens and Staphylococcus aureus are examples of this group. Nevertheless, these micro- organisms can be pathogens in the strict sense under different conditions (WHO 2006).

The term pathogen is most commonly used to refer to infectious organisms (WHO 2009)

Example

The ability of a pathogen to inflict damage upon the host is controlled by a combination of factors, in particular the nature of the organism (for example its virulence) and the susceptibility of the host. Several factors combine to determine the susceptibility of the host, including age, nutritional status and immunity. Immunocompromised individuals, for example, are highly susceptible to infection by pathogens, whereas well-nourished young adults are typically less susceptible to infection (WHO 2006). Pathogens include viruses, bacteri, fungi and parasites (WHO 2009).

References

• (2006) Stedman's Medical Dictionary. Lippincott, Williams and Wilkins.
• WHO (2006) Protecting groundwater for health
• WHO (2009) Health impact assessment glossary: E-learning modules

Links

• WHO — The Health and Environment Lexicon
• Water, sanitation and health web site