Commensal:
Commensalism is a relationship between two organisms in which one organism benefits, and one is unaffected. This can be contrasted with other types of symbiosis, such as mutualism and parasitism. The supposed difference between commensalism and other types of symbiosis is that in commensalism, the second party or host remains unaffected. Some scientist argue that this is likely improbable, and that most commensalism will be found to be mutualism or parasitism once the effects on the host can be appropriately studied. Other scientists argue that commensalism does exist when the effect on the host is imperceptible. [biology dictionary]
Noted in “The covid-19 virus affects our gut – but we still don’t know how,” Michael Marshall, NewScientist (6 May 2023, paywall):
However, a different picture emerges from studies that focused specifically on disruption to the gut microbiome, suggesting that this may be linked to an increased risk of death from covid-19. The stool samples that Ng and her team examined revealed that many helpful “commensal” bacteria can become depleted when people are infected with the coronavirus, while harmful ones become more populous. The fungi in the gut – the mycobiome – have shown similar disruptions. Crucially, those with more severe illness tended to have more disrupted microbiomes, mimicking the results of other studies.
