What makes some microbes cause transient sickness while others become a permanent part of our bodily ecology?
Posted: Tue Mar 31, 2020 12:56 pm
I've been pondering this question since long before the CoVid-19 thing arose. But now I'm all the more curious.
To the best of my understanding, some microbes to which we are exposed take up residence in our bodies for only a short time. They're either killed off by our immune systems or eradicated through antibiotic or antiviral treatment. In the process we acquire temporary or permanent immunity. Others, it seems, become a permanent part of our microbiome and can, under the right conditions, emerge later--sometimes repeatedly--to cause illness years down the road. Examples of viruses that tend to take up permanent residence include the herpes virus, which hides out in nerves, as well as the HIV and chickenpox/shingles viruses. On the bacterial side, we have the TB mycobacterium, which walls itself off in granulomatous tissue but can become active years later. Clostridium difficile is considered treatable but is notoriously difficult to eradicate, so it often hangs around in the gut undetected. I'm not sure how to characterize ordinary strep and staph, which are ubiquitous in the environment and which we generally think of as being easily treatable with antibiotics. However, people who have MRSA are often susceptible to multiple recurrences throughout life.
What generalizations can be made about why some microbes come and go and others take up residence as a permanent part of our microbiome? Or am I wrong in making this distinction? In other words, is it possible that every virus or bacterium to which we are exposed stays with us (or has the potential to stay with us) for life?
What implications might this have for the current coronavirus epidemic?
To the best of my understanding, some microbes to which we are exposed take up residence in our bodies for only a short time. They're either killed off by our immune systems or eradicated through antibiotic or antiviral treatment. In the process we acquire temporary or permanent immunity. Others, it seems, become a permanent part of our microbiome and can, under the right conditions, emerge later--sometimes repeatedly--to cause illness years down the road. Examples of viruses that tend to take up permanent residence include the herpes virus, which hides out in nerves, as well as the HIV and chickenpox/shingles viruses. On the bacterial side, we have the TB mycobacterium, which walls itself off in granulomatous tissue but can become active years later. Clostridium difficile is considered treatable but is notoriously difficult to eradicate, so it often hangs around in the gut undetected. I'm not sure how to characterize ordinary strep and staph, which are ubiquitous in the environment and which we generally think of as being easily treatable with antibiotics. However, people who have MRSA are often susceptible to multiple recurrences throughout life.
What generalizations can be made about why some microbes come and go and others take up residence as a permanent part of our microbiome? Or am I wrong in making this distinction? In other words, is it possible that every virus or bacterium to which we are exposed stays with us (or has the potential to stay with us) for life?
What implications might this have for the current coronavirus epidemic?