(ORDO NEWS) — Approximately half of the stool samples from patients previously diagnosed with Covid-19 showed viral RNA a week after infection, and four percent continued to do so after seven months.
A team of geneticists, microbiologists and physicians from Stanford University (California, USA) showed that SARS-CoV-2 coronavirus RNA in some cases persists in human feces even seven months after infection. Gastrointestinal symptoms of this lingering illness include nausea, vomiting, and abdominal pain.
This is the first large-scale study that has assessed the presence of viral ribonucleic acid in stool samples from patients with mild to moderate COVID-19, collected at different times after the onset of the disease.
After two and a half pandemic years, we know that Covid-19 is a disease with a variety of manifestations, from respiratory to gastrointestinal and systemic.
Although SARS-CoV-2 primarily infects the respiratory system, the presence of symptoms such as nausea, joint pain, and diarrhea, combined with evidence that the virus resides in tissues of almost the entire body, shows that the pathogen is spreading beyond the respiratory system.
The authors of the new study set out to better define the presence of SARS-CoV-2 in the gastrointestinal tract and its significance for human health in both the short and long term, since there was not enough data on this.
They used stool samples and respiratory swabs from more than a hundred people with mild to moderate Covid-19.
Analyzes were regularly collected within ten months from the moment of diagnosis in the spring of 2020. Participants were under observation, so scientists were able to monitor the development of symptoms.
Among the 113 participants who provided stool samples, the results showed that viral RNA was present in feces in 49.2 percent of the six days after Covid-19 was detected.
In the first month, the number of such people fell to 11 percent, while the viral load also decreased. In the feces of 12.7 percent of patients, RNA of the infectious agent could be detected after four months, and in 3.8 percent after seven months.
At first, SARS-CoV-2 RNA was present in large quantities in nasopharyngeal swabs, but then this trend began to change in the opposite direction. According to the authors of the work, it follows from this that the purification of the respiratory epithelium from the virus occurs faster than the tissues of the gastrointestinal tract.
This means that the gastrointestinal tract can serve as a “place” for the localization of long-term Covid-19, which affects the majority of those who have been ill. Participants in the study complained of related symptoms nausea, diarrhea, and abdominal pain.
Unlike samples from the nasopharynx (green line), in the faeces (blue line), coronavirus RNA could be detected even 210 days after infection
“No one really knows what causes long-term Covid-19,” said Ami Bhatt, MD, Stanford University. “But our study shows that SARS-CoV-2 is able to “hide” in the intestines for months. It is possible that the long-term coronavirus illness and the wide range of symptoms it causes is due to the immune system’s response to viral RNA in hidden reservoirs throughout the body.”
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