More than two years after the global fight against the epidemic, with the large-scale spread of the virus, the strain is also constantly mutating, and the recent rapid spread of the mainstream strain of the new crown in China, resulting in many cities once again in a state of silence and control. The new crown virus is a lung inflammation caused by the new coronavirus, which not only causes great damage to the lungs, but also affects the human immune system and other organs. At present, human understanding of the new crown virus is only the tip of the iceberg.
On April 12, 2022, researchers at Stanford University in the United States published a study entitled "Gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA suggest prolonged gastrointestinal infection" in the Cell sub-journal Med (Figure 1). The study found that virus residues in the stool of COVID-19 patients can be detected even if the virus in their lungs has been cleared for weeks or months[1].
Figure 1 Research results (Source: [1])
In order to analyze the presence of viral RNA in the gastrointestinal tract of infected patients with new crown, researchers at Stanford University conducted a 10-month follow-up monitoring of the dynamic change of fecal new coronavirus RNA shedding in 113 patients with confirmed mild symptoms of new crown between April and July 2022. The time points for stool collection were concentrated on day 3 (range = 0-7 days), day 14 (8-21 days), 28 days (22-35), 120 days (75-165), 210 days (166-255), and 300 days (more than 255 days). In addition to these stool samples, throat swabs are taken daily for nucleic acid detection during the initial trial (Figure 2).
Figure 2A shows the timeline of sample and data collection; Figure B shows the basic characteristics of the experimental population (Source: [1])
The study found that within a week after the diagnosis, researchers could detect viral residues in 49% of patients' stools; even 4 months after the virus had been undetected in patients' lungs, viral RNA could still be detected in 12.7% of patients' stools; 7 months later, viral RNA was still present in 3.8% of patients' stools, and what is even more incredible is that after 10 months, when the new crown virus test was negative, viral residues could not be detected. In addition, the researchers found that some common gastrointestinal symptoms such as abdominal pain, nausea, vomiting, etc. were also associated with fecal shedding of SARS-CoV-2 RNA (Figure 3).
Fig. 3 Comparison of viral RNA detection in stool samples and respiratory samples at different collection times (Source: [1])
During the course of the study, patients with SARS-CoV-2 RNA, whose stools could be detected, also showed intestinal symptoms. In the first month, the researchers found that patients who had detected viral RNA in their stool were more likely to report symptoms such as abdominal pain, nausea, and vomiting. In addition, the respiratory and constitutional symptoms of runny nose, headache, and body pain are associated with the presence of stool SARS-CoV-2RNA (Figure 4).
Fig. 4 Stool samples from patients 210 days after COVID-19 infection show that the presence of viral RNA is associated with gastrointestinal symptoms (Source: [1])
In this regard, Dr. Ami Bhatt, an associate professor of medicine and genetics at Stanford University, said that this may explain why some patients infected with the new crown experience gastrointestinal symptoms such as abdominal pain, nausea, vomiting and diarrhea. SARS-CoV-2 may stay in the gut and even other tissues for longer than it does in the respiratory tract, and it can basically continue to stimulate our immune system and induce some long-term symptoms.
The results of the study provide a theoretical basis for predicting the epidemic situation by detecting community wastewater viruses, which is of great guiding significance for public health epidemic prevention. The study found that 3.8% of COVID-19 patients still have viral RNA in their stools 7 months after infection, which can complicate and make it more complicated and difficult for communities to prevent epidemics.
Written by | Guo Yaqing
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[1] NatarajanA, Zlitni S, Brooks EF, et al. Gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA suggest prolonged gastrointestinal infection. Med (N Y). 2022Apr 13. doi: 10.1016/j.medj.2022.04.001. Epub ahead of print. PMID: 35434682; PMCID: PMC9005383.
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