A new study from researchers at Stanford University has found some COVID-19 patients can shed fragments of the virus in their feces up to seven months past their initial infection. The researchers hypothesize the persistence of viral material in the gut may potentially play a role in long COVID symptoms.
Across the first few months of the pandemic, as the novel coronavirus SARS-CoV-2 rapidly spread, most people thought of COVID-19 as a straightforward respiratory disease. However, as 2020 progressed and scientists learned more about this new disease, it became apparent that many COVID-19 patients were experiencing severe gastrointestinal problems.
Around one in five COVID-19 patients were reporting gut problems including nausea, diarrhea and stomach pain. But at the time it wasn’t entirely clear whether these gastrointestinal symptoms were due to the virus directly infecting the gut, or simply a result of more general systemic inflammation.
Now, in 2022, it is relatively clear that SARS-CoV-2 can infect gut cells but what isn’t clear is just how long viral particles can persist in the gut beyond the acute infection. This new research followed 113 patients with mild to moderate COVID-19 for up to 10 months.
The study found traces of SARS-CoV-2 viral RNA in the feces of just under 50 percent of the cohort within a week of their initial diagnosis. Four months later 12.7 percent of patients were still shedding viral fragments in their feces, and seven months later four percent were still showing viral RNA.
The researchers are cautious to stress the viral fragments being detected are not infectious viral particles. So this research is not at all suggesting this is a novel transmission route for COVID-19. Instead, the findings offer more evidence SARS-CoV-2 does directly infect cells in the gut. And the persistence of viral particles in the gut are hypothesized as potentially playing a role in the lingering symptoms linked to long COVID.
“No one really knows what causes long COVID, but our study shows that SARS-CoV-2 can hide out in the gut for months,” said Ami Bhatt, an author on the new study. “Maybe long COVID – and the wide variety of symptoms it causes – is due to the immune system’s response to viral proteins in hidden reservoirs throughout the body.”
Bhatt hypothesized the gastrointestinal symptoms often seen in long COVID patients could be an inflammatory response to the prolonged presence of SARS-CoV-2 viral particles in the gut. It is all speculation at this stage but the fact that a significant number of mild COVID cases were still shedding viral particles months after an infection is evidence the virus can persist in other parts of the body.
The new study also calls into question the veracity of using wastewater surveillance as a way of tracking the prevalence of SARS-CoV-2 in a city or county. Bhatt said if levels of the virus in wastewater are going to be used to determine public health decisions then it is crucial to understand the long-term dynamics of viral shedding.
“We’re clearly seeing large and increasing amounts of the Omicron subvariant BA.2 in wastewater nationwide,” Bhatt added. “At the same time, there have been lay reports that Omicron is more likely than previous variants to cause GI symptoms. So, is this wastewater increase really proportional to the number of people who are infected? Or are more people shedding the virus in their feces for longer?”
Of course, more work will be needed to try and answer these questions but this new study offers clear evidence that extended shedding of SARS-CoV-2 RNA in feces can last for months following mild disease.
The new study was published in the journal Med.
Source: Stanford Medicine