London School of Hygiene & Tropical Medicine

The workshop was hosted by te National Institute of Communicable Diseases (NICD) and brought together collaborators from NICD; the Gauteng City-Region Observatory (GCRO); the Christian Medical College in Vellore, India; London School of Hygiene & Tropical Medicine; Bristol University; and the South African Centre for Epidemiological Modelling and Analysis (SACEMA) at Stellenbosch University.   

By Joe Mesri Pryce and Kath O’Reilly

The collaborator meeting we attended in Johannesburg included presentations of the successful use of wastewater surveillance to monitor COVID-19 trends in the South African province, Gauteng, as well as updates on the development of new laboratory methods and modelling tools for utilising wastewater data to estimate effective reproduction numbers. Discussions also took place to discern consensus around the potential applications and future prospects of wastewater-based epidemiology, standardisation of methods for LMICs, and priorities for future research.

Using wastewater surveillance in different geographical settings

We didn’t just sit in a meeting room though, we also got to visit  several wastewater sampling sites currently used for environmental surveillance in Gauteng. These included informal sampling points covering populations in temporary housing settlements in Soweto district, and a tour of the Bushkoppies Wastewater Treatment Works, a large treatment plant in South Johannesburg that processes 200 megalitres of wastewater per day. This field visit highlighted the challenges involved in using wastewater sampling for surveillance of a complex geographical area where different populations are served by significantly varied sewage infrastructure. Observing the sampling process also emphasised the potential for variability in concentrations of pathogen genetic material that may be observed - even between samples taken simultaneously - that must be considered by epidemiological models. 

What’s next

As an immediate outcome from the meeting, we have now put plans in place to gather additional datasets to support modelling and analysis, improve how the research questions will be answered, and identify ways that each individual project can work more collaboratively to improve the research outcomes. This week was the first that we had all met in person, and this interaction was really valuable to support collaborative working.

Several CMMID members were invited to attend an Africa CDC meeting the following week in Cape Town, where representatives from multiple African countries and stakeholders described ongoing activities in environmental surveillance. Reflecting on the meetings we had in South Africa, what was most striking was that while researchers within each country were largely carrying out similar processes for sample collection and analysis in the lab, every lab had its own methods and ways of tackling problems encountered. It was apparent that the different methods used were not due to wanting to be different, but because of reagent and equipment issues and establishing that the current method ‘worked’ while previously trialled methods did not. While the innovation being implemented in each setting was very impressive, translating the data generated into comparable metrics could be challenging. For many of the target pathogens a quantitative metric from environmental surveillance data is important, consequently the collection of additional meta-data, for example an approximate measure of wastewater flow, would greatly enhance the value of the data collected. However, there is currently no consensus on what data to collect if flow is not directly measurable. This, and many other topics were discussed to establish a way forward.  The meetings were valuable because of the depth and diversity of people’s expertise, and hopefully meeting in person will support future collaborations.