SARS-CoV-2 sewage surveillance in low-income countries: potential and challenges

Abstract

This paper reviews the recent findings in the detection of SARS-CoV-2 in sewage samples. We discuss how wastewater-based surveillance (WBS) can be used as a complementary tool to help the fight against COVID-19 spread, particularly in low-income countries with low sewage coverage and where the testing coverage is deficient, such as Brazil. One of the major challenges on WBS is the use of different protocols to estimate the number of infected people in a community from the quantification of SARS-CoV-2 in wastewater. Therefore, we assembled and reviewed all the relevant data available to date about this topic. Virus concentration and detection methods were reviewed as well, and some of them can be performed in most of the microbiology and environmental engineering laboratories in low-income countries, as discussed. Moreover, the monitoring and sampling plan should represent the local reality. Thus, we suggest unique strategies for sewage sampling and monitoring in different sewerage network points and the slums, despite the possible logistics difficulties involved. Considering the low levels of sanitation in most urban agglomerates in Brazil, WBS can potentially assume a crucial role as a cost-effective strategy to monitor the circulation of the virus and assess the real prevalence of COVID-19.

Defining the methodological approach for wastewater-based epidemiological studies—Surveillance​ of SARS-CoV-2

“…Similarly, WBE can be used as a complementary tool to help in the fight against the spread of COVID-19. WBE can be a key tool to track SARS-CoV-2 circulation in under-developed areas ( Calabria de Araujo et al, 2021 ). It is possible to estimate the number of infected people in a specific sewage catchment area if the virus concentration in the wastewater per day and the virus concentration in the faeces of an infected person per day are known ( Qu et al, 2020 ).…”

“…One of the major challenges on WBE is the use of different protocols ( Wu et al, 2020a ). Strategies for WBE are unique and therefore is standard protocol for SARS-CoV-2 surveillance from wastewater ( Calabria de Araujo et al, 2021 ) and to estimate the number of infected people in a community from the quantification of SARS-CoV-2 in wastewater ( Wu et al, 2020a ). The SARS-CoV-2 RNA concentration (copies/L) measured in the sewage may be dependent on excretion from the infected person, immunity level, locality and age groups ( Hemalatha et al, 2021a , Ahmed et al, 2020a , Foladori et al, 2020 , Bivins et al, 2020 , Hellmér et al, 2014 ).…”

“…Advanced detection tools (RT-qPCR) for rapid, efficient identification may require standard laboratory equipment, being unfeasible for many countries ( Medema et al, 2020 , Wurtzer et al, 2020 , Ahmed et al, 2020b ). The persistence of virus in sewage influenced by factors such as temperature, population, drain flow rate, infected individuals, time and day of sampling, dilution effect, community socio-economic conditions, extent of sanitation and facility, humidity, rainfall event, etc ( Calabria de Araujo et al, 2021 ). The supplemental quality control data and standardization in sampling design, sample processing, data interpretation, and reporting are mandated to reliably interpret data generated by these efforts for informing public health interventions ( Calabria de Araujo et al, 2021 ).…”

“…The persistence of virus in sewage influenced by factors such as temperature, population, drain flow rate, infected individuals, time and day of sampling, dilution effect, community socio-economic conditions, extent of sanitation and facility, humidity, rainfall event, etc ( Calabria de Araujo et al, 2021 ). The supplemental quality control data and standardization in sampling design, sample processing, data interpretation, and reporting are mandated to reliably interpret data generated by these efforts for informing public health interventions ( Calabria de Araujo et al, 2021 ). WBE also can detect different viral variants currently circulating in the population.…”

SARS-CoV-2 detection in wastewater using multiplex quantitative PCR

“…However, the sampling should be planned according to the country's needs, as in many cases a significant portion of produced sewage does not reach the WWTP. In this respect, public schools and community toilets could represent an easier track of the community health ( Calabria de Araujo et al, 2020 ).…”