condition for an organism to be a pathogen (1 Viewer)

[stressedadfff]

is it any more complex than being a disease causng agent?

 

[zizi2003_]

Besides being just a 'disease causing agent', it's also important to note the adaptations and virulence factors that a micro/macro-organisms has to be deemed 'pathogenic' - this includes examples like viruses having viral proteins that adhere to the host's cell surface receptors to basically invade the host cell to replicate its own viral genome. Other examples include the use of vectors to overcome the skin barrier or specialised mouth parts in macro-organisms (eg ticks) that make them pathogenic in nature -like our body has defence mechanisms/adaptations, so do pathogens

 

[Eagle Mum]

Whilst many organisms are purely pathogenic to humans (disease causing) and the severity of illness depends on host factors, there are also organisms that are usually commensal (colonise the host without causing disease), but under certain conditions, can become pathogenic. Examples are some of the streptococci bacteria and candida fungi that normally colonise our skin & mucosa.

Conditions that cause these usually benign organisms include loss of skin & mucosa integrity as zizi2003 has already described, the host becoming immunosuppressed or immunocompromised due to immune system dysfunction, HIV infection, chemotherapy dugs etc, as well as disturbances to the balance of species of organisms, such as killing off of other protective organisms by antibiotics.