Writing Exercise #1

Prompt: List as many human non-infectious diseases that you can think of that are influenced by microorganisms.

I know that many different microbes have influence on a myriad different non-infectious diseases, and that a lot of these diseases have to do with the human microbiome. The microbiome has been implicated in many different metabolic diseases including diabetes and obesity. This makes sense, due to the direct interface that the microbiome has with the gut, one of the main body sites for metabolism. Additionally, certain cancers can be influenced by the microbiome. There are certain bacteria and viruses that can both promote certain cancers, including a correlation between the Human Papilloma Virus (HPV) and cervical cancer. On the other hand, in the presence of soluble fiber in the large intestine, microbes have been shown to metabolize butyrate, a short chain fatty acid that cancerous colon cells are unable to metabolize, leading to their eventual lysis. In this way the bacteria are preventing colon cancers. 

Perhaps most interestingly of all is the association with the gut microbiome and the presence of neural and mental health conditions. The gut and the brain are directly connected by the Vagus nerve in what is called the “Gut-Brain Axis”. Microbes have the ability to produce metabolites like neurotransmitters that can directly interact with the Vagus nerve, and the nerve itself can release metabolites that alter the microbial composition of the gut. Studies have shown a relationship between the microbiome and diseases like Alzheimer’s or Parkinson’s disease, as well as mental health conditions like depression, anxiety, and schizophrenia. It’s important to keep in mind that just because these health states are associated with microbes doesn’t necessarily mean that they are caused by microbes, just that there is a relationship between said microbes that hasn’t been well studied. 

Outside of the gut, the microbiome of the mouth has been associated with dental caries, gingivitis and have been implicated in the development of canker sores. The microbiome of the skin has been associated with dandruff, body odor, and eczema. The microbiome of the vagina is associated with a healthy pH and an appropriate flora, but when the microbiome isn’t made up of microbes that it is meant to be (certain species of Lactobacillus), it can lead to bacterial vaginosis. Microbes have also been associated with systemic infections introduced either orally or via leaky gut, which can itself be caused by microbes. 

Some ‘diseases’ behave differently. One example of a disease state related to microorganisms that is a little bit odd is the association between parasitic infections and the development of the aforementioned eczema. Parasitic infections are unique, requiring different white blood cells than a bacterial infection, and often teaching the immune system about different antibodies. These unique infections actually end up teaching the immune system. In one study, pregnant women from non-industrialized countries were given an anti-worming agent, and those mothers gave birth to babies that had three times the rate of eczema as those born to mothers who received a placebo. This has opened up the idea that the development of the immune system when exposed to parasites can influence other future diseases states, but of course, more research needs to be done.

When it comes to disease states, aside from things like accidents or natural disasters, microbes have their role to play in essentially every possible disease state imaginable.