Evaluation of possible SARS-CoV-2 fecal-oral transmission route in Latvian COVID-19 patients

The novel coronavirus SARS-CoV-2 poses a great public health crisis. Since December 2019, it has spread all over the world and still causing huge damage and disruption of everyday life. The understanding of all transmission pathways of this virus is very important to implement appropriate pandemic regulation strategies. The aim of this study was to evaluate possibility of SARS-CoV-2 fecal-oral transmission route. Nasopharyngeal swab, urine and fecal samples from 79 COVID-19 patients (38 men [median age 59] and 41 women [median age 68]) were analyzed in this study. SARS-CoV-2 genomic sequence was detected using commercially available qualitative real-time polymerase chain reaction (PCR) kit in nasopharyngeal swab, urine and fecal samples' total RNA. All positive samples were additionally tested for SARS-CoV-2 load using commercially available quantitative real-time PCR kit. All PCR kits used various SARS-CoV-2 target genes to exclude non-specific results and internal control. SARS-CoV-2 genomic sequence was found in 70 out of 79 (87%) nasopharyngeal swabs, 43 out of 79 (54%) fecal samples and 4 out of 79 (5%) urine samples. Analyzing SARS-CoV-2 load values, the highest median viral load was found in fecal samples - 46204 (p=0.0009 [IQR: 5424.0-3919660.0]) viral copies/ml in comparison to nasopharyngeal swabs, where median 6004 (IQR: 468.3- 32859.0) viral copies/ml was found. The lowest viral load values were found in urine samples (range: 40 - 5000 viral copies/ml). No significant differences were found between men and women in SARS-CoV-2 distribution and viral load. Frequent presence of SARS-CoV-2 genomic sequence and significantly higher viral load values in fecal samples indicate on the possibility of existence of fecal-oral transmission route for this virus.