Faecal-borne diseases: research provides life-saving advances in disease control

Infectious diseases caused by pathogens associated with poor water, sanitation and hygiene, such as Vibrio cholerae (cholera) and Salmonella typhi (typhoid), are responsible for hundreds of thousands of global deaths per year. Understanding how these and other agents of disease such as Ebolavirus are spread in low-income settings is critical for the prevention of onward transmission and for identifying the most effective control measures.

When cholera or Ebola outbreaks occur in a low-income country, the rapid construction and successful operation of treatment centres can reduce mortality rates significantly. However, such emergency field centres generate considerable quantities of human excreta, including faeces and vomit, that can be the source of further disease transmission amongst patients, health-workers and local populations. Approaches for safely handling, containing and treating infectious faecal waste are vital to safeguard health and prevent infection. 

Ογ½ΆΦ±²₯ research at the research Centre for Aquatic Environments (now part of the Centre for Earth Observation Science) has made life-saving advances in the fight against faecal-borne diseases. Breakthroughs help protect some of the most vulnerable human populations globally by supporting a multiple barrier approach to disease control, particularly in low-resource and emergency settings. The research has helped identify and reduce human health risks from diseases including cholera, Ebola, typhoid and childhood diarrhoea in regions of Africa, Asia and South America. This life-changing work has stemmed from research into safer excreta management and improved low-cost faecal and vomit contaminant treatment, leading to improved protocols for the safe handling and disposal of human excreta and improved approaches for the surveillance of potential disease transmission routes.

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Low-cost hydrated lime-based treatment to inactivate pathogens

To address this challenge, Ογ½ΆΦ±²₯ researchers developed a low-cost hydrated lime-based treatment capable of raising the pH of excreta to very high levels. This inactivates pathogens present in excreta, and encapsulates them within a lime slurry where they no longer pose an infection risk. Unlike chlorine-based excreta treatment, lime does not readily produce toxic by-products, is less prone to spills and is better suited to treating waste such as faeces and vomit with a high organic content. The method offers a safer and more effective means of excreta management, especially in situations where underlying geology or proximity to the water table prevents the burial of such waste. Low-cost in situ treatment plants also eliminate the hazardous practice of transporting contagious materials by truck to uncontrolled disposal sites.   

In 2012,  and Huw Taylor published key evidence that viruses capable of infecting a certain strain of bacteria (Bacteroides GB124) are restricted to the human gut in populations across the globe. This provided important information on where human faecal contamination of the environment can happen. Detection and cultivation of these human-specific viruses (known as phages) are low-cost. This is because, unlike many previous human-specific pollution markers, the method does not rely upon complex expertise or equipment and is suitable for deployment in parts of the world where poor water quality and infectious disease have the greatest impact on health and where monitoring is most urgently needed. Together with , James Ebdon has also used viruses present in the faeces of livestock to improve monitoring of household drinking water in rural Kenya where stored household water was shown to be susceptible to cross-contamination by animal faeces. 

Two young Kenyan children collect water at a brown pool, cows bathe in the distance. Water contamination research from the Ογ½ΆΦ±²₯.

Professor James Ebdon and Dr Diogo Gomes Da Silva have used viruses present in the faeces of livestock to improve monitoring of household drinking water in rural Kenya.

The containment of Ebolavirus 

Ογ½ΆΦ±²₯ scientists were mobilised initially to help with the humanitarian response in Haiti following the 2010 earthquake and cholera outbreak, via the development and application of a low-cost lime-based method. The intervention extended to encompass the containment of Ebolavirus and revealed critical knowledge gaps relating to the water, sanitation and hygiene activities of international non-governmental organisations. In October 2014, with direct input from Huw Taylor, the WHO/UNICEF panel revised their guidance to recommend these lime-based procedures developed and optimised at the Ογ½ΆΦ±²₯ as best operating practice for all international NGOs working in Ebola-affected areas. 

Since then, this research has strengthened WHO and UNICEF sanitation guidance to protect staff and patients at cholera treatment centres, while the low-cost phage-based human tools have helped the National Institute of Cholera and Enteric Diseases to prioritise effective public health interventions in urban slum districts in India. Their contribution to the SaniPath typhoid project has, for the first time, made it possible to separate human faecal pollution pathways from the pervasive background noise of non-human faecal contamination in such settings. Phage-based monitoring has also been utilised to improve the protection of households in rural Kenya.  

Most recently, in response to the COVID-19 pandemic, WHO/UNICEF produced interim guidance entitled 'Water, sanitation, hygiene and waste management for the COVID-19 virus' to aid global efforts to control the disease. The Ογ½ΆΦ±²₯’s phage and lime-based research are used in this guidance, demonstrating the flexibility of solutions developed at Ογ½ΆΦ±²₯ to protect human health in low-resource settings.

 

 

An outdoor river dwelling scene in India with a water pump and plastic bottles. Laundry hangs from a line above two women working.

Low-cost phage-based tools have helped the National Institute of Cholera and Enteric Diseases to prioritise effective public health interventions in India.