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COVID-19, Gut and Potential Role of Probiotics
Coronavirus disease 2019 (COVID-19) - an international public health emergency declared by the World Health Organization , has massively spread across 210 countries & territories around the globe . Several generations have been exposed to COVID-19 at different stages of life.  COVID & Digestive Symptoms – Eyes will see what the mind knows !! Although...
Coronavirus disease 2019 (COVID-19) - an international public health emergency declared by the World Health Organization , has massively spread across 210 countries & territories around the globe . Several generations have been exposed to COVID-19 at different stages of life. 
COVID & Digestive Symptoms – Eyes will see what the mind knows !!
Although COVID-19 most commonly presents with respiratory symptoms, such as cough and shortness of breath, there is evidence that the illness can also present with non-respiratory symptoms, most notably digestive symptoms such as diarrhoea, diminished appetite, and nausea 
Expression of SARS-CoV-2 virus in the Digestive Tract
The digestive symptoms of COVID-19 likely manifest because the virus enters the target cells through angiotensin-converting enzyme 2 , a receptor found in the gastrointestinal tract - both the upper and lower, where it is expressed at nearly 100-fold higher levels than in respiratory organs . Viral nucleic acid was reported to have detected in feces in over half of the patients infected with COVID-19 virus 4 and in almost one-fourth of cases' stool samples test positive when respiratory samples are negative 
The relevance of GI Symptoms in the Diagnosis of COVID
Most of the emerging COVID-19 literature has emphasized on severe or critically ill patients, yet over 80% of patients have only mild disease . It is important to describe the clinical characteristics of low severity infection patients to provide information for early clinical recognition of COVID so as to facilitate rapid self-quarantine for people with presumed symptoms who are not sick enough to warrant hospitalization.
Moreover, mild symptomatic patients can be mediators of rapid dissemination of COVID-19 by unwittingly spreading the virus in the outpatient setting; making this group to be seemingly a major driver of the pandemic  Because COVID-19 testing has largely focused on patients with respiratory symptoms—not digestive symptoms—it is possible that there is a large cohort of undiagnosed patients with low severity illness but with digestive symptoms, such as diarrhea, who could be unknowingly spreading the virus
Mild COVID with More Digestive Symptoms - Silent Spreaders
In a study conducted in 206 patients with low severity, COVID-19 found notable results indicating the presence of a unique subgroup of COVID-19 patients with mild disease severity marked by the presence of digestive symptoms. These patients are more likely to test positive for viral RNA in stool, to possess a longer delay before viral clearance, and to experience a delay in diagnosis compared to patients who had only respiratory symptoms 
Potential Role of Probiotics in COVID-19
There are studies which indicate that COVID-19 might be associated with intestinal dysbiosis causing inflammation and poorer response to pathogens  thus making a case for probiotic strains that restore gut homeostasis . The gut microbiome has a critical impact on systemic immune responses, and immune responses at distant mucosal sites, including the lungs 
Potential benefits of Lactobacillus in Respiratory Infections
There is certainly acceptable scientific data with the use of various Lactobacillus strains in improving outcomes in respiratory infections. Studies have indicated that Lactobacillus based species helps to reduce the incidence of laboratory-confirmed respiratory viral infections in elderly individuals . In another study conducted in 742 children, Lactobacillus administration led to a reduction in the risk for nosocomial gastrointestinal and respiratory tract infections in paediatric facilities.
The potential of Lactobacillus through a more severe spectrum of respiratory illness is substantiated through a study conducted in mechanically ventilated patients indicating the use of Lactobacillus was associated with a lower incidence of development of ventilator-associated pneumonia, thus reflecting potential clinical utility for prophylaxis of ventilator-associated pneumonia(VAP) in a high-risk ICU population 
In summary, orally administered probiotic strains can reduce the incidence and severity of viral respiratory tract infections (RTIs). At a time when doctors are using drugs with little anti- COVID-19 data, probiotic strains documented for anti-viral and respiratory activities could become part of the armamentarium to reduce the burden and severity of this pandemic 
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MBBS,MD, DNB (Cardiology)
Dr Prem Aggarwal, (DNB Cardiology) is an Cardiologist by profession and also the Co-founder of Medical Dialogues. An avid researcher, he is currently associated with GB Pant Hospital (GIPMER) New Delhi as a PhD Fellow pursuing his research on the topic of Angioplasties on Surgical Rejects