The CoV-2 virus that causes COVID is a respiratory bug, right? They say we catch it, not from surfaces or food, like we do norovirus, but from airborne exposure—we breathe it in. That of course, means that it causes respiratory problems. Makes sense, right? Well, Sarah Carter, 36, from San Mateo, CA, caught the virus in late 2023. Her main symptom was not respiratory but relentless diarrhea that became so sever she had to take an ambulance to the ER. The runs caused her to become dehydrated, which in turn caused a spike in her blood pressure and heart rate. She urgently needed IV fluids to treat it all. After three more days of diarrhea she finally felt better. But, six months later the GI symptoms reappeared overnight without her being infected again. Nearly everything she ate set off diarrhea. She also had bloating and pain so severe that she said it felt like acid was running through her intestines. A gastroenterologist eventually diagnosed her with post-infectious irritable bowel syndrome (IBS).
What in the world is a respiratory virus doing messing with her entrails, especially months after being infected? Did it make a wrong turn somewhere?
We have gotten accustomed to testing for COVID when we feel crummy and run a temperature, have a sore throat, runny nose, loss of smell, cough, etc.—all symptoms of respiratory infection. But Dr Rohit Jain, an internal medicine doc at PennState Health told Time that when someone complains of problems affecting the exit at the other exit of the body: i.e., nausea, diarrhea, vomiting, etc., he always tests for COVID. Another doctor, Mark Rudd, chief of infectious diseases at the U of Nebraska Medical Center also weighed in saying that, “COVID-19 is really a GI-tract disease.”
What??
If it “really is a GI disease” why are we wearing masks, distancing, and worried about respiratory infection rather than hand washing and sanitizers??
The SARS-CoV-2 virus and its disease, COVID, are very strange and threw the medical establishment for a loop after they first appeared on the scene at the end of 2019, and after COVID became a world-wide pandemic in early 2020. Docs dealt with myriad, seemingly unrelated symptoms in different patients; symptoms such as brain fog, loss of smell, severe pneumonia, hemorrhage issues that led to black toes and lungs that looked like they had filled with chocolate pudding, among many others; all from the same virus. Now add to that befuddling mix, GI problems to what was believed a respiratory virus,and COVID presents a conundrum. Docs have to now factor in the fact that many people experience no, or only mild gastrointestinal symptoms, while other patients experience significant digestive problems that can distract from the pulmonary problems which complicate diagnoses.
As we have learned more about COVID over the last few years, it has become clear that infection symptoms can also include loss of appetite, nausea, vomiting, diarrhea, and stomach pain, according to Jain’s research. A 2023 study published in Nature Communications reported that 36% of COVID patients are likely to develop GI disorders such as ulcers, pancreatitis, IBS, and acid reflux. Another recent study in Clinical Gastroenterology and Hepatology found that 40% of adults hospitalized with COVID, had at least one GI relapse a year or more later. While both of these were small studies, they are in close agreement regarding the incidence of COVID GI problems. And like other symptoms of long COVID, the GI problems can last many weeks. That is quite concerning. Weeks of diarrhea, for example, is much more than an immense inconvenience and major mess, it is a serious medical issue. But not all patients experience these symptoms, just like not all patients lose their sense of smell, had black toes, or developed long COVID. Try to diagnose and understand COVID with this range of variable symptoms! How confusing.
How can the same virus cause runs from both ends of the body; the nose and the other end? Among the things we have learned over the last few years is that the CoV-2 virus infects cells that express the ACE-2 protein. While ACE-2 normally is important for certain cell functions, the virus decided to use it as a receptor on which to grab onto and then enter cells. The protein is found on many different types of cells throughout the body, but it is expressed in especially high levels in the lungs, which helps explain COVID’s respiratory symptoms. It turns out that ACE-2 is also highly expressed in cells of the GI tract. That explains the intestinal complications. Also, because it is found in the GI tract that could possibly make feces from infected animals, like bats, a great way to widely spread the virus to other animals, just like migrating birds spread the avian flu virus to poultry flocks and dairy herds. In fact, in 2012, six Chinese mine workers removing guano in a bat-filled cave where flying flittermice were found with COVID, developed severe respiratory symptoms. Three of them died. COVID infection from contaminated bat guano is suspected because the Wuhan lab eventually found evidence of an unknown coronavirus in the patient samples. But, this was years before the CoV-2 virus had been discovered, so the CoV-2 link to their disease comes with some uncertainty. Maybe the virus in ca-ca could be a way to spread it between people too, like norovirus is spread. To my knowledge, human-to-human spread this way has not been shown, but it makes sense to this scientist that it could. After all, since the virus is found in feces, wastewater surveillance has proven to a useful tool for tracking CoV-2 spread among human populations. It is routinely found in poop, and there is a good possibility that the Chinese workers caught it from the bat scat they were shoveling. Together, that makes it very likely that humans can spread it to other people via unsanitary practices. But, at this time, that is just the opinion of your sometimes humble correspondent. We will see.
We also now know that the virus can hide in the nooks and crannies of the bowel for months, or even years, according to Ziyad Al-Aly, MD, an epidemiologist at the Washington University School of Medicine in St. Louis, who co-authored the Nature Communications study on chronic post-COVID GI symptoms that was cited above. This might explain why gut-related symptoms can long outlast the initial acute infection. But other possibilities to explain long-COVID GI problems continue to be investigated. This is another “we shall see” issue.
We also know that the virus can cause widespread and sometimes long-lasting inflammation, potentially affecting various organs throughout the body including the gut. GI inflammation can affect the gut microbiome, which is the collection of microbes that normally live in the GI tract and that are good for us. We have long known that changes in the gut microbiome can have manifold health effects affecting GI health, and even the well-being of the heart, kidneys and brain, including Alzheimer’s disease, which is a possible complication of COVID. Disruption of the GI microbiome also is related to obesity and diabetes and it is notable that COVID disease also is associated with new-onset diabetes. Inflammation in the gut can also damage the lining of the intestines, making them “leaky” so that nutritional goodies from foods you normally would absorb across your gut into the blood stream, instead escape into the abdomen, causing immune cells to mount an allergy-like response to foods. COVID-induced inflammation can also chew away at the nerves that control normal gut contractions (peristalsis) that move food along, and interfere with neurological signals in the gut causing pain. Not fun, ask Sarah Carter!
Since the start of the pandemic in early 2020, GI docs have noticed an uptick in IBS in COVID patients. Medical scientists have long known that other gastrointestinal infections, like those from norovirus, giardia (a parasite), or salmonella (bacteria), can lead to IBS as well as functional dyspepsia, a type of chronic indigestion that causes frequent feelings of fullness and stomach pain or burning, like acid running through your innards. Does that sound familiar? Now we can add the respiratory virus, CoV-2, to the list of infectious agents that can cause IBS and other digestive problems.
Bottom line: So, gut problems are added to the manifold issues associated with COVID disease. CoV-2 is a nasty bug that you don’t want to catch. Get vaccinated and spare yourself all these problems!