Table 1.

GI involvement in SARS-COV-1, MERS and COVID-19

Disease	SARS-CoV-1	MERS	COVID-19
Start of outbreak	2002	2012	2019
Virus	SARS-CoV-1	MERS-CoV	SARS-CoV-2
Origin	bat → civets10; China, Guangdong Province	bat → camels11; Saudi Arabia	bat → unknown12 ; China, Wuhan Province
GI symptoms	Diarrhoea, 16–73%8	Diarrhoea, 25%8	Diarrhoea, 32.5%15
	Nausea and vomiting, 20–35%13	Nausea, 14%14	Nausea, 11.7%15
		Vomiting, 8%14	Vomiting, 3.9%16
	Abdominal pain	Abdominal pain	Abdominal pain/discomfort, 4.4%15
Time of onset of diarrhoea	Onset or during illness17	Onset or during illness 8	Onset or during illness15
RNA shedding in stools	Maximum duration 126 d18	Seen in 14.6% of patients14	Mean duration 17.2 d18
			Maximum duration 126 d18
Stool RT-PCR positive rate from the time of diagnosis	47% week 11997% week 21954% week 319	16% week 11914% week 219NA week 319	25% week 11937.5 week 219NA week 319
Viral load (log10 copies/mL or CT value)	6.52 week 1197.95 week 219	4.5 week 1194 week 219	31.65 CT week 11926.5 CT week 219
	5.33 week 319	0 week 319	NA week 319
Entry receptor	ACE2 receptor	DPP4 receptor	ACE2 receptor
Pathology	Intestines: no obvious pathological changes/non-specific changes; depletion of mucosal lymphoid tissue20	Intestines: no obvious pathological changes reported	Intestines: mucosal damage in oesophagus with multiple round herpetic erosions and ulcers and numerous infiltrating plasma cells and lymphocytes as well as interstitial oedema in the lamina propria of the stomach, duodenum and rectum21,22

CT value: cycle threshold value; DPP4: dipeptidyl peptidase-4; NA: not applicable.