COVID-19 (Coronavirus Disease-2019), caused by the severe acute respiratory syndrome Coronavirus (SARS-CoV-2), spread rapidly from China to almost the entire world, affecting millions of people across 199 countries. We are sure you all know by now that the hallmark signs of COVID-19 are fever, cough, and shortness of breath. But, according to a Stanford Medicine study, nausea, diarrhea, and other gastrointestinal symptoms are getting overlooked in COVID-19 patients. Researchers conducting another study also found that many patients infected with the new coronavirus (SARS-CoV-2) also suffered from loss of appetite, vomiting, and diarrhea.
The SARS-CoV-2 virus enters the intestinal cells after spike proteins bind to ACE-2. This virus uses an angiotensin-converting enzyme (ACE-2) as a receptor to enter human cells. Then it triggers the release of the cytokines. Cytokines are small proteins that cause inflammation. This can also be one of the causes of gastrointestinal symptoms.
These studies also state that fecal-oral transmission, which is the spread of the virus through food contaminated by an infected person’s feces, might also be a possibility. This was because RNA and proteins from the virus were found in infected patients' feces even after the respiratory symptoms subsided. The available data are preliminary and cannot be used to conclude anything. The other point to be noted here is that even though traces of the virus have been found in feces, there is still no evidence showing how virulent they are.
In this article, we have included the findings of various studies conducted worldwide on the gastrointestinal symptoms of COVID-19, how this virus damages your gut, and the fecal-oral transmission route.
What Are the Typical Symptoms of COVID-19?
SARS-CoV-2 is a new strain of Coronavirus, a family of viruses known to cause other fatal respiratory illnesses like the Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS). Most infected people (around 81 %) develop only mild or no symptoms, about 14 % develop severe symptoms, and only 5 % are critically ill and need respiratory support. Adults over 65 years and others with a pre-existing condition run a higher risk of developing severe symptoms if infected.
According to the CDC (the Centers for Disease Control and Prevention), this is the percentage of people affected by the following symptoms:
Some patients also experience symptoms of other influenza-like illnesses, such as
Loss of smell and taste.
What Are the Gastrointestinal Symptoms of COVID-19?
As SARS-CoV-2 is widely studied as a virus affecting the respiratory tract, studies to determine its involvement in the gastrointestinal system are still ongoing.
A study in the Zhejiang Province of China examined 651 patients and showed that 11.4 % of COVID-19 patients exhibited at least one gastrointestinal symptom like nausea, diarrhea, or vomiting. The age of the patients examined was, on average, 46.1 years, and 10.8 % had pre-existing liver disease. It was also noted that patients with GI symptoms experienced considerably high fever, malaise, headache, and shortness of breath.
In the US, the first COVID-19 patient had nausea, cough, vomiting, abdominal pain, and loose bowel movements while hospitalized. They eventually tested positive for SARS-CoV-2 RNA and could detect the virus in his stool sample. It was also reported that another COVID-19 patient showed blood in stools as an initial symptom, but this patient’s stool sample was not tested for the virus.
Some COVID-19 patients develop only gastrointestinal symptoms, while some have respiratory symptoms. A study by Stanford University found that 1 in 3 infected patients who had a mild infection had symptoms affecting the digestive tract. Another study in Beijing found that 3 to 79 % of infected patients developed gastrointestinal symptoms. The common gastrointestinal symptoms are
Diarrhea - According to a study published in the American Journal of Gastroenterology, which examined 206 patients, 117 patients showed digestive tract symptoms, and 19.4 % of these 117 patients had diarrhea as the initial symptom.
Vomiting - Researchers of the Beijing study noted that vomiting was more common in infected children than adults. After analyzing all the reported cases associated with GI symptoms between December 2019 and February 2020, it was found that between 6.5 to 66.7 % of children experienced vomiting, while only 3.6 to 15.9 % of adults exhibited this symptom.
Loss of Appetite - The Beijing study also found that 39.9 and 50.2 % of infected people lose their appetite.
Apart from these symptoms, the Beijing study also reported:
Nausea in 1 to 29.4 % of people.
Gastrointestinal bleeding in 4 to 13.7 % of people.
Abdominal pain in 2.2 to 6 % of people.
How Does COVID-19 Result in Gastrointestinal Symptoms?
Scientists believe that the Coronavirus (SARS-CoV-2) enters the digestive system through cell surface receptors angiotensin-converting enzyme 2 (ACE2). ACE2 receptors are present in the respiratory and gastrointestinal tract epithelium. But, these receptors are 100 times more common in the digestive tract than in the respiratory tract. The virus replicates after it enters the cell.
Typically, the acidic environment in the stomach kills the virus that enters the digestive tract. People who take medicines for acidity to neutralize stomach acids might unknowingly create a safe environment for SARS-CoV-2 to enter the cells and multiply. This might be the cause of gastrointestinal symptoms. Studies are ongoing to determine the relationship between acidity drugs and the risk of developing digestive symptoms.
COVID-19 can also cause gastrointestinal symptoms by altering the gut microbiome, which contains trillions of microorganisms that can metabolize, digest, fight infection, and regulate mood. Any modification or damage to this gut microbiome causes opportunistic infections, depression, anxiety, and gastrointestinal symptoms, such as nausea and diarrhea. Also, on a six-month follow-up, COVID-19 showed a significant decrease in different phases of infection.
Can SARS-CoV-2 Affect the Liver?
A considerable number of COVID-19 patients have experienced mild to severe liver damage. This damage to the liver is due to the disease process.
A study by the American College of Gastroenterology (ACG) found that around 20 to 30 % of infected patients had abnormal liver enzymes. Another study that examined 148 COVID-19-infected patients in China reported that 50.7 % of patients had abnormal liver functions during hospitalization. Patients with pre-existing liver conditions are more prone and require special attention.
Most liver injuries from this infection are mild, but severe damage is also possible. In critically ill patients, a higher degree of liver injury was noted, for which doctors administered medicines to protect the liver (hepatoprotective drugs).
Can SARS-CoV-2 Affect the Pancreas?
An examination of 52 patients with COVID-19 pneumonia found that 17 % had a pancreatic injury. These patients did not exhibit symptoms of pancreatitis (inflammation of the pancreas). As ACE2 receptors are present in the pancreas, theoretically, SARS-CoV-2 can damage the islet cells and cause acute diabetes. Out of the nine patients with pancreatic injury, 6 showed abnormal blood sugar levels.
Does COVID-19 Spread Through the Fecal-Oral Route?
The Coronavirus can be found in the respiratory droplets of patients a couple of days before the onset of symptoms and up to 2 weeks after signs vanish.
Recently, researchers demonstrated that a few infected children showed a high number of virus RNA in feces. This study also stated that viral RNA could be detected in the feces between 2 weeks and more than a month. These findings increase the suspicion of the fecal-oral route of transmission.
Positive stool results, even after negative respiratory samples, point towards the possible replication of SARS-CoV-2 in the gastric epithelial cells. This is why scientists are working hard to gain evidence for possible fecal-oral transmission. There is no evidence yet that the Coronavirus spreads through eating food contaminated by the virus present in an infected person’s feces.
Effects of COVID-19 on People With Pre-Existing Gastrointestinal Disorders:
Certain gastrointestinal disorders, like inflammatory bowel disease (IBD), increase the risk of developing some viral infections. No studies so far have shown that people with IBD or other gastrointestinal disorders are more prone to develop COVID-19. But it is just that they may develop worse outcomes after getting affected by COVID-19.
What to Do If a Person Develop Gastrointestinal Symptoms?
Experiencing digestive symptoms does not mean that a coronavirus has infected you. Various other conditions can result in similar symptoms.
If a person experiences GI symptoms, stay home, keep the body hydrated by drinking plenty of water and ORS (oral rehydration solution), and avoid foods that irritate your stomach. If symptoms get worse, or if a patient develops respiratory symptoms, consult a doctor.
The spread of COVID-19 and most other influenza-like illnesses can be prevented by:
Wash hands frequently and properly.
Cover the face while sneezing or coughing.
Stay away from people who exhibit flu-like symptoms.
Avoid going to crowded places.
If you decide to go to a crowded place, wear a mask.
Maintain social distancing.
Stay home as much as possible.
Get vaccinated against COVID-19 if a person is still not vaccinated.
For more information on COVID-19 and its atypical symptoms, consult an online infectious specialist.