The use of quantitative microbial risk assessment to estimate the health risk from viral water exposures in sub-Saharan Africa: A review

Abstract

Access to microbiologically safe water is not a reality for many people throughout Sub-Saharan Africa where there is widespread occurrence of viruses in water sources. Exposure to this water can lead to adverse health risks including diarrhoeal disease. To a limited extent in Sub-Saharan Africa, the quantification of the human health risk associated with exposure to virally contaminated water has been done through the use of quantitative microbial risk assessment (QMRA). To understand the scope of the information available on this region, two systematic reviews were done to collect previously published literature from Sub-Saharan Africa on (1) prevalence and quantification of viral contamination in water and (2) QMRAs assessing the risk from exposure to water contaminated by viruses. The results of the 2 reviews were then summarised including, for the QMRAs, exposure and dose-response assumptions, input parameters, and risk outcomes. The results found the prevalence of 10 viruses (1-100%) in drinking, ground, irrigation, surface, and waste waters from eight countries with South Africa having the most information on water contamination by viruses. Quantified viral concentration data was reported for ~50% of the papers, for 6 viruses (entero-, human adeno-, noro-, rota-, sapo-and Hepatitis A virus), and ranged from (10-4-10 11 viruses/liter). Additionally, 22 QMRAs were identified for 6 viruses (entero-, human adeno-, noro-, rota-, coxsackie B, and Hepatitis A virus) from 4 countries demonstrating that QMRA has not been used extensively in this region. The majority of these QMRAs concluded that the risk of infection, illness, or Disability Adjusted Life Year (DALY) was exceptionally high and in excess of acceptable risk limits indicating a public health concern. In conclusion, water is contaminated with viruses, risk from exposure to viruses in water was extremely high for these 4 Sub-Saharan Africa countries, and QMRA is not a widely adopted methodology. Finally, some QMRA limitations were observed such as the need for more viral concentration data, collection of site-or region-specific exposure data, application of commonly used doseresponse models, addressing susceptible populations such those with human immunodeficiency virus (HIV) infection in the risk characterisation, and access to free software.

Navigating Data Uncertainty and Modeling Assumptions in Quantitative Microbial Risk Assessment in an Informal Settlement in Kampala, Uganda

“…In this study, the harmonization factor (to convert qPCR results to dose–response model inputs) was varied uniformly from 0 to 1 for C. jejuni and Shigella and from 1.43 × 10 –3 to 0.1 for adenovirus due to the variable assumptions used in the existing literature. ,− Sensitivity analysis results were consistent with other QMRA studies performed in resource-limited settings showing model sensitivity to concentration data, , exposure parameters, ,, and dose–response parameters. , …”

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa

“…Additionally, Quantitative Microbial Risk Assessment (QMRA) could be used to estimate population health risks posed by these waterborne pathogens and inform water management strategies (Howard et al 2006;Owens et al 2020). Although QMRA has been widely used in developed countries (Bichai and Smeets 2013;Owens et al 2020), less-developed countries such as those in Africa, with limited data and resources, have greater challenges when applying this technique (Howard et al 2006;Chigor et al 2014;Van Abel and Taylor 2018). A recent review of QMRA in sub-Saharan Africa (Van Abel and Taylor 2018) outlined these challenges such as the lack of quantification data and defined several steps including the collection of further data on virus detection, concentration and infectivity, to improve this methodology within the region.…”

Interlinkages of Water-Related SDG Indicators Globally and in Low-Income Countries

“…Atangana 2021 found that groundwater in South Africa contains heavy metals [65]. Van Abel 2018 stated that in South Africa, the frequency of virus exposure (with a range of 10−4-1011 viruses/L) from water, especially drinking, ground, irrigation, surface, and waste waters, is extremely high [66]. Adverse health risks, including those from NTDs, are associated with these water risks.…”