The new website is: covid19waterblog.wordpress.com
One of their first posts focuses on the transmission of COVID-19 via wastewater.
There has been quite some talk about SARS-CoV-2 shedding in faeces and what that might mean for the water industry. As I see it, there are two aspects to this conversation: the first is a concern that sewage may contain infectious SARS-CoV-2 viruses; and the second relates to the more theoretical potential of using SARS-CoV-2 RNA concentration in sewage as a public health surveillance tool.
1. Is sewage contaminated with infectious SARS-CoV-2 viruses?
While COVID-19 is primarily a respiratory illness, the possibility of faecal-oral transmission was raised quite early (Yeo et al. 2020). From the information we have to date, it appears as though many people infected will excrete SARS-CoV-2 RNA in their faeces. A snapshot of reported presence in stool samples includes:
- Six studies reported from China: 9 out of 17 patients were positive (Pan et al. 2020) ; 39 out of 73 patients positive (Xiao et al. 2020); 8 out of 10 children positive (Xu et al. 2020); 44 out of 153 faecal samples positive (Wang et al. 2020) ;12 out of 22 patients positive (Chen et al. 2020); 41 of 74 patients positive (Wu et al. 2020)
- In Singapore, 4 out of 8 patients were positive (Young et al. 2020)
- The first reported case in the United States tested positive on day 7 (Holshue et al. 2020)
- In Germany, 8 out of 9 patients were positive (Woelfel et al. 2020)
- In France, 2 out of 5 patients were positive (Lescure et al. 2020)
However most importantly as highlighted in the WHO technical brief, there is limited indication of infectious viruses in faeces, let alone survival to sewage effluent. This is comforting, and yet it made me wonder: how many studies have tried to culture SARS-CoV-2 from faecal samples? Of the studies listed above, to my knowledge only 2 tried to culture the virus: Wang et al. (2020) reported successfully culturing 2 out of 4 samples, identifying the ‘live’ virus by electron microscopy. Woelfel et al. (2020) attempted to culture 13 samples taken between days six to twelve from four patients without success. There is a need for more information on the success and failure of culture of SARS CoV-2 in faecal samples.