Routine SARS-CoV-2 wastewater surveillance results in Turkey to follow Covid-19 outbreak
Authors: Kocamemi Bilge Alpaslan , Kurt Halil , Sait Ahmet , Kadi Hamza , Sarac Fahriye , Aydın Ismail , Saatci Ahmet Mete , Pakdemirli Bekir 
Published: December 2020

1.AbstractA global pandemic of Coronavirus Disease 2019 (Covid-19) caused by severe acute respiratory syndrome coronavirus 2 (SAR-CoV-2) declared by WHO in March 2019 is still ongoing. As of 13th of December 2020, 70 million people were infected by SARS-CoV-2 and 1.5 million people lost their lives globally (WHO, 2020). Since March 2019, diagnosis of Covid-19 cases has been done through PCR test of samples from nasopharyngeal and throat swabs. However, in March 2019, it was reported that the faeces [1] and urine [2] of all infected people contain SARS-CoV-2. Later, numerous researchers [3-7] detected SARS-CoV-2 in faeces of both symptomatic and asymptomatic patients. Moreover, some studies [1,4,8-12] suggested the possibility of extended duration of viral shedding in faeces after the patients’ respiratory samples tested negative. In this respect, SARS-CoV-2 wastewater-based epidemiology (WBE), i.e., wastewater surveillance, aiming to estimate the distribution of asymptomatic and symptomatic individuals in a specific region has received worldwide attention. Various research groups worldwide [1, 13-54] have started SARS-CoV-2 detection in wastewater since WBE provides tracking whole population by testing a small number of wastewater samples in a specific region and can predict SARS-CoV-2 RNA in human faeces a few days to a week before onset of symptoms. This makes WBE quite economic tool for continual tracking of decreasing or increasing trend of the Covid-19 in a particular region. However, up to date, almost all of the WBE studies have been performed with samples from a few treatment plants. There was no reported nationwide wastewater surveillance study that has been integrated into a national Covid-19 management strategy by decision makers. Nationwide, SARS-CoV-2 surveillance studies have great potential to reflect the actual distribution of Covid-19 cases in a community by accounting not only symptomatic patients tested but also asymptomatic patients having no or mild symptoms and not been tested. As opposed to clinical surveillance studies, wastewater-based surveillance studies will reflect the number of cases in a community by testing one sample from a treatment plant serving this community instead of performing individual swab tests.Turkey, which is among the few countries that started wastewater based surveillance studies at the early stages of pandemic is a leading country, performing a nationwide surveillance study. The distribution of Covid-19 cases throughout the country via SARS-CoV-2 measurements in influent, effluent and sludge samples of wastewater treatment plants (WWTPs) located in 81 cities through May 2020-June 2020 was conducted [36, 51, 52]. In June 2020, nationwide routine sampling through 22 regional identified cities has been started. However, from June to September 2020 all samples were detected negative due to problems with RT-pCR primer targeting RdRp gene of SARS-CoV-2 genome. Since September 2020, routine sampling from 22 cities of Turkey with 2 weeks sampling period (weekly for mega city Istanbul) has been continued and regional Covid-19 distributions have been reported as viral loads on color-scale maps. To the best our knowledge, this is the first routine nationwide surveillance study indicating Covid-19 distribution regularly using color-scale presentation on a map.