By Brian Rose
Coronavirus is taking over the world since the end of 2019. It is an acute respiratory illness caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2).
The pandemic began in the Chinese province of Wuhan and, in no time, spreads globally and results in a number of deaths. The researchers are still unable to develop an effective vaccine or treatment for this deadly disease. Although vaccines manufactured by various pharmaceutical companies are in the last stages of human trials, it’ll take time to prove their efficacy and be approved.
How is Coronavirus Transmitted?
Until developing an effective and safe COVID-19 vaccine, we all have to take precautionary measures to protect ourselves and others. It is important to know the modes of transmission of coronavirus, and its signs and symptoms, management, and complications for the purpose of preventing infection. Having enough knowledge about how it spreads is the only way to stop its spread and stay safe. The researchers are studying SARS-COV-2 (coronavirus) and come up with new details about the coronavirus because the virus is capable of mutagenesis, which changes its ability to infect individuals.
The most common transmission mode is by airborne droplets, when the infected individual’s cough, sneeze or speak releases infected droplets in the air and on surrounding surfaces. People coming in contact with such droplets or contaminated surfaces within one meter of distance can get the infection by inhaling or by touching contaminated surfaces. It is the reason, public health measures of wearing masks, washing or sanitizing hands, and keeping a distance of at least one meter from others are stressed upon. Preventing its transmission from one infected person to another is the only way to control coronavirus spread.
Due to the increased number of COVID-19 patients presenting with non-specific symptoms including diarrhea, nausea, abdominal pain, and vomiting, it is believed that the fecal-oral route also transmits coronavirus means that the infected person sheds the virus in feces. The fecal-oral transmission of coronavirus is linked to its entry into host cells via angiotensin-converting enzyme-2 (ACE-2), which are also present in the GI tract (esophagus, stomach, ileum, and colon). In the stomach, if the virus manages to escape gastric defense, it can infect enterocytes and cause fecal shedding. It is seen that viral RNA is positive in an infected individual’s feces for an extended period, raising the possibility of fecal-oral transmission of coronavirus.
How Long Coronavirus Stays in the Human Body?
For preventing the transmission of coronavirus from one person to another, it is important to know how long it stays in the body. Because as long as it stays, it carries the risk for transmission either by the airborne or fecal-oral route. Once a person contracts coronavirus, the symptoms usually appear after 2 to 14 days, and recovery usually takes 2 to 3 weeks. Severe cases may take up to 6 weeks to recover. Due to this variation in recovery times, it is clear that it stays in the body longer than others in some patients. This lingering virus in the human body is termed viral persistence, and it tells how long an infected person is contagious and how long they must remain isolated. Another term, “viral clearance,” is also used, which means the clearance or disappearance of the virus from the human body in response to the body’s immune system or therapeutic agent.
Studies Showing Fecal Shedding of Coronavirus
A study was carried out to determine the persistence and clearance of coronavirus from the human body involving patients who are in the recovery phase from COVID-19. The results of RT-PCR (reverse transcriptase-polymerase chain reaction) were collected from the samples taken by oropharyngeal, feces, urine, and serum. RT-PCR differs from traditional PCR in the sense it has an extra step in the process where it converts the RNA isolated from RNA-viruses to DNA prior to amplification. The results are published as median range, showing that oropharyngeal swab remains positive for around 11 days, feces RT-PCR remains positive for 11 to 14 days. Urine samples for most of the patients stayed negative.
The study also showed that in patients with glucocorticoid treatment, the duration of fecal viral RNA detection is longer (20 days) than those without glucocorticoid treatment (11 days). With this study, it is confirmed that coronavirus persists in feces longer than oropharynx. In other words, it takes longer to get cleared from the feces than the other sites in the human body. And because of this delayed clearance of viral RNA from feces, it is vital to test the stool sample for the virus even when the oropharyngeal swab is negative in convalescent patients.
Another study showed that patients who present with gastrointestinal symptoms are most likely to shed virus in feces, and 41% of COVID-19 patients who participated in this study had positive RT-PCR for SARS-COV-2.
A review of 26 studies was carried out involving 824 COVID-19 patients. 540 patients were tested for fecal viral RNA, and 291 (54%) came out positive. 199 patients with positive fecal viral RNA were followed up with stool testing, and 63% (125) of patients showed continuous shedding of viral RNA after the nasopharyngeal swab became negative. The duration of fecal shedding after a nasopharyngeal swab was negative ranged from 1 to 33 days while a patient sheds it for up to 47 days.
All these studies showed that coronavirus persists in the stool for an extended period, and due to fecal-oral transmission, it is essential that the patient must be tested negative for fecal viral RNA before resuming the isolation period. However, further studies are in progress to determine the fecal-oral transmission, but until now, it is clear that SARS-COV-2 sheds in the feces of an infected patient and can be a source of transmission to others. Therefore to break the chain of transmission, patients must also be tested for fecal samples and must be followed up for fecal samples during the recovery phase. They must also not be allowed to break their quarantine or isolation until their RT-PCR fecal samples come negative for viral RNA apart from a negative nasopharyngeal swab.