Research published in the journal Environment International, and led by Newcastle University and Ardhi University in Tanzania, took advantage of Newcastle’s innovative suitcase laboratory to study waterborne disease transmission pathways in an informal settlement, where cholera is endemic. In the settlement, pit latrines provide basic on-site sanitation and local groundwater is the main household water source.

Professor David Werner, of Newcastle University’s School of Engineering, said: “Following the Covid-19 pandemic, most people will be familiar with methods like qPCR tests, sequencing, and wastewater epidemiology. Already years before Covid we worked with colleagues in Tanzania to make these methods portable and affordable. Our aim was to bring these tools within reach of those facing the greatest water security challenges.”

Joint corresponding author, Dr Shaaban Mrisho Mgana from Ardhi University’s Environmental Engineering Department added: “Pit latrines provide essential onsite sanitation services to millions of people in Dar es Salaam. But there are concerns about their role in infectious disease transmission and impacts on groundwater resources. Using wastewater epidemiology, we demonstrated that about 5% of the population in the settlement were asymptomatic carriers of Vibrio cholerae bacteria.

“With state-of-the-art molecular diagnostics we further showed that human waste is the source of these bacteria in the groundwater below the settlement. We also showed that natural attenuation of bacterial hazards in the subsurface is insufficient to protect the boreholes used by the community from faecal contamination, especially in the rainy season.

“Finally, we devised and demonstrated an affordable hazard mitigation measure by inserting one meter of sand at the bottom of pit latrines, which achieved 90-99.99% removal of Vibrio cholerae and other faecal bacteria from the percolating leachates.”

Safe sanitation

Despite the recognition of the human right to water and sanitation by the United Nations through Resolution 64/292, 3.6 billion people still lacked safely managed sanitation in 2020, including 1.7 billion without basic sanitation facilities. The Global Challenges Research Fund (GCRF) which supported the research collaboration is part of the UK’s official development assistance (ODA) and funds cutting-edge research to achieve the United Nations sustainable development goals, including Sustainable Development Goal 6 (SDG6), clean water and sanitation.

Newcastle University leads two prestigious Global Research Hubs set up to tackle world's toughest challenges, the UKRI GCRF Living Deltas Hub and the UKRI GCRF Water Security and Sustainable Development Hub. The Times Higher Education Impact Rankings 2022 ranked Newcastle University top in the UK, and 8th in the world for action on sustainable development. Dr John Snow must be proud of his alma mater, and those who are following his footsteps.

Reference

Halla, F., Massawa, S., Joseph, E., Acharya, K., Sabai, S., Mgana, S., & Werner, D. (2022). Attenuation of bacterial hazard indicators in the subsurface of an informal settlement and their application in quantitative microbial risk assessment. Environment International, 167, 107429. doi: 10.1016/j.envint.2022.107429