Detecção e monitoramento do Sars-Cov-2 em águas residuárias em Santarém, Pará

Abstract

Viruses are infectious particles, highly adaptable and capable of infecting different human tissues, such as SARS-CoV-2, (Severe Acute Respiratory Syndrome Coronavirus 2) responsible for the disease COVID-19. In view of the above, the aim was to monitor and identify the presence of SARS-COV-2 in wastewater at strategic points, using a rapid and accurate analytical method. The study occurred in the urban area of Santarem at three sampling points for wastewater collection: (i) EEE of Residencial Salvação (ii) ETE Irurá wet well and (iii) ETE of Hospital Regional. The collection occurred manually, where 500 ml was collected every 12 minutes for 4 h, and at the end 2L of composite sample was obtained. The analyses occurred in parallel with the biweekly collections in the period from March to September 2021, totaling 13 determinations. In the Laboratory of Wastewater Treatment the physical-chemical parameters of the samples were analyzed (Temperature, pH, Alkalinity, Dissolved Oxygen, Phosphorus, Solids, Nitrogen, Ammonia, Chemical Oxygen Demand, Nitrite, and Nitrate) and submitted to the analytical methods of the Standard Methods for the Examination of Water and Wastewater. In the Molecular Biology Laboratory the samples went through four steps: virus concentration by the hydrophilic MCE electronegative membrane filtration method (0. 45-μm-pore-size membrane filtration method); RNA extraction with the commercial Maxwell RSC Viral Total Nucleic Acid Purification Kit, detection and quantification of the virus by reverse transcription reaction and real-time DNA polymerase chain reaction (PCR) performed in the 7500 Real Time PCR System equipment, which used the commercial Bio-Manguinhos SARS-CoV-2 (E/RP) Molecular Kit. The wastewater from the three treatment plants presented peculiar physical-chemical characteristics for virus reduction, such as temperature, COD, and solids. The qualitative application for the detection of the SARS-CoV-2 virus RNA molecule was for positive or negative diagnosis (+/-) and quantitative for absolute quantification (viral load/number of copies). The virus was detected in 24% of samples, with the highest number of positive samples in the hospital, there was no presence in the TEE, and only one sample was positive in the EEE. The study found that it is possible to perform wastewater-based epidemiological monitoring for the detection of the SARS-CoV-2 viral load at strategic points of sewage disposal.