Wastewater Surveillance Programs for COVID-19 and Other Pathogens Led by African National Public Health Institutes
On March 3, 2022, the IANPHI Africa Regional Network held a webinar to share experiences of African national public health institutes that are conducting wastewater surveillance programs for COVID-19 and other pathogens. Monitoring wastewater for SARS-CoV-2 has proven to be a very useful tool for detecting new variants and track trends. The webinar featured presentations by Ghana Health Service and South Africa’s National Institute for Communicable Diseases, as well as a question-and-answer session moderated by Kyeng Mercy, Africa CDC’s event-based surveillance lead.
Summary of Presentation by Dr. Dennis Laryae, Senior Public Health Specialist and Deputy Director of Surveillance at Ghana Health Service
Ghana has been implementing an Integrated Disease Surveillance and Response (IDSR) strategy for priority diseases, conditions and events since 2002. Before COVID-19, efforts focused on polio eradication. Ghana Health Service implemented a pilot project in 2016 at six sites in two regions. Since then, the polio environment surveillance program has expanded to 14 sites in seven regions and has become an integral part of Ghana’s efforts for the eradication of polio.
During the COVID-19 pandemic, Ghana Health Service developed a strategy for wastewater surveillance for SARS-CoV-2 in low-income urban settings with the support of the Bill & Melinda Gates Foundation and selected two study sites for a pilot project. Wastewater samples were collected weekly from a sewage system and from public latrines.
Lessons learned from wastewater surveillance for COVID-19 are guiding further actions such as including genomic sequencing. Ghana Health Service has secured support from the Rockefeller Foundation to take the project to the next level. Ghana Health Service is also looking to further strengthen laboratory capacity for environmental surveillance, and explore the development of an integrated environmental surveillance strategy that includes other pathogens such as Vibrio cholera, Group A Rotavirus and Salmonella Typhi. Developing a curated and integrated data repository, online dashboard, and decision support system will also be necessary.
Summary of Presentation by Dr. Kerrigan McCarthy, Specialist Pathologist at the National Institute for Communicable Diseases, South Africa
Like Ghana, South Africa also first developed an environmental disease program on polio. The National Institute for Communicable Diseases (NICD), a World Health Organization’s Polio Collaborating Center, was appointed as a regional reference laboratory prior to 2010. NICD’s Centre for Vaccines and Immunology began its polio environmental surveillance in 2018, in line with WHO’s recommendations.
The success of polio environmental surveillance led to an emerging interest in the use of SARS-CoV-2 wastewater epidemiological patterns in the spring of 2020. The results showed a correlation between pathogens in wastewater samples and the number of confirmed cases. Scientists were able to show and provide policy-makers with wastewater analysis results within one week for the quantitative analysis and two to three weeks for the genomic analysis.
However, wastewater-based epidemiology faces challenges regarding methodology and scientific acceptation as well as skepticism from the population. In the future, Dr. McCarthy would like to see the scope of wastewater surveillance network widen to include other communicable diseases, and advocacy to encourage the public and policy-makers to use the data.
Question and Answer Session Summary
During the Q&A session, Kyeng Mercy shared Africa CDC’s recommendations to implement wastewater surveillance in order to monitor early environmental signs of virus transmission and identify communities where targeted interventions can be implemented to decrease transmission.
Dr. McCarthy talked about the possibility to overlay wastewater surveillance data with non-traditional epidemiological data, explaining that surveillance using communication channels can be a useful tool, even if it had not been tried yet.
Finally, speakers talked about environmental variation that could affect samples such as wastewater flow rates during sample collection. Dr. McCarthy explained that surveillance results could be distorted when these data are not taken into account due to the lack of availability of flow rate data.
Writer: Liza Thadani, editors: Marie Deveaux and Andisheh Nouraee