In a study published in the journal Pathogens, Michigan State University researchers have created what they believe to be the first model examining how Group A rotaviruses (RV) move about through waterways.
A 2008 study published in The Lancet found that “worldwide in 2008, diarrhea attributable to rotavirus infection resulted in 453,000 deaths (95% CI 420,000-494,000) in children younger than 5 years-37% of deaths attributable to diarrhea and 5% of all deaths in children younger than 5 years.” RV is understood to be one of the major causes of acute gastroenteritis (inflammation of the stomach and intestines) in infants and young children globally.
The team first reviewed literature on RV prevalence and emissions. They used their literature review findings to set the parameters for their unique model, the Global Waterborne Pathogen model for RV (GloWPa-Rota model). The GloWPa-Rota model estimates the global distribution of RV emissions to surface water, allowing researchers and public health officials to pinpoint areas of high RV incidence. The model outputted data to be organized in a log10-based grid, visualizing ‘hotspot’ regions of emissions.
Joan Rose, the Homer Nowlin Chair in water research at Michigan State University, told MSU Today that “many countries are at risk of serious public health hazards due to lack of basic sanitation. With this map, however, we can assess where viruses are being discharged from untreated sewage and address how disease is being spread. With that, we can design a treatment and vaccination program that can help prevent sewage-associated diseases.”
Rose continued on to explain that “the great advantage of a modeling approach is getting a better understanding of the situation in areas where no monitoring data exist, but where we do have model input available.”
Importance of Wastewater Treatment
Global sanitation and access to safe water is still an issue of extreme importance. Per the research, in 2010 “an estimated 1.8 billion people drank unsafe water and an additional 1.2 billion people were exposed to drinking water with substantial sanitary risk. As of 2004, approximately 2.6 billion people lacked adequate sanitation and this figure has seen little improvement.”
What’s more, wastewater treatment facilities outside of industrialized nations seem to lack the appropriate filtration systems to deal with RV concentrations. The researchers found that primary treatment systems utilizing wastewater sedimentation do very little to reduce RV concentrations, which is concerning given their prevalence in developing nations worldwide. Previous research into RV reduction by this method resulted in data that the team used in their model–data that corresponded with a mere 20% reduction in RV concentrations.
A Rather Unexpected Finding
The team concluded that “our analysis can be used to evaluate different sanitation scenarios also on country level. The analysis of UK and Nigeria suggests that connecting the population to sewers may even increase emissions to surface water, if the sewage is not properly treated. Connection to sewers of people that previously used a latrine or open defecation will now take RV and other pathogens to surface water. Even in the UK, where almost everyone is connected to a sewer, but where only a limited percentage of the sewage is treated by tertiary treatment, emissions are considerable. Very few countries have full coverage with tertiary treatment that includes disinfection. This would be essential to reduce RV emissions to surface water. The focus of the SDGs [Sustainability Development Goals] on ending open defecation may therefore result in increased emissions to surface water unless it is planned in conjunction with improved wastewater treatment to protect water resources.”
In other words, connecting more individuals to the sewer system will actually increase RV distribution through surface water unless the sanitation systems are upgraded significantly to specifically reduce RV concentrations, and as seen in the analysis of the United Kingdom, this holds true in the developed world as well.
The Science and the People
- Study: Global Occurrence and Emission of Rotaviruses to Surface Waters
- Journal: Pathogens
- Authors: Nicholas M. Kiulia, Nynke Hofstra, Lucie C. Vermeulen, Maureen A. Obara, Gertjan Medema, and Joan B. Rose