Two PhD studentship opportunities (deadline Dec 2020)

The disease ecology of urban litter – solid waste management and vector-borne diseases in Malawi

Professor Richard Quilliam

Discarded plastic waste in the peri-urban environment is a serious challenge for sustainable waste management and for the delivery of environmental and public health. In many cities in sub-Saharan Africa, plastic wastes block urban drainage systems, and during rain events this often leads to localised flooding, with an increased risk of exposure to raw sewage in standing water. Importantly, urban plastic litter can act as a transient receptacle for rainwater and thus provide a larval habitat for mosquitoes. Although the role of plastic pollution on mosquito ecology is poorly understood, this increased abundance of mosquito habitat in the peri-urban environment can lead to increased vector density and the incidence of vector-borne diseases such as malaria, Zika, dengue and lymphatic filariasis. Urban wastes can also be an attractant for flies, e.g. filth flies such as the house fly (Musca domestica), which can transfer enteric diseases such as dysentery, diarrhoea, typhoid and cholera, particularly if the waste has been in contact with a source of faecal contamination (e.g. following flooding or via scavenging by domestic or wild animals). Consequently, urban litter may also play an important role in the emergence of novel zoonotic diseases or genes for anti-microbial resistance. Therefore, quantifying whether plastic waste in the peri-urban environment is providing breeding sites for disease vectors, is important for addressing the Sustainability Development Goals (e.g. SDG3), and critical for incentivising policy-makers to provide resources to local communities for the removal of urban litter as part of a sustainable strategy to reduce disease burden and the risk of emerging infectious diseases.

The aim of this project is to uniquely link pathogen ecology with disease & waste management within a multidisciplinary framework and provide tangible evidence for an increased disease burden due to peri-urban plastic waste.

Key research questions:
Understanding the multidisciplinary interactions between sustainable disease management & sustainable waste management will be directly addressed through this studentship by focussing on the following questions:
1. Do different types of plastic litter preferentially attract mosquito oviposition, and can plastic litter facilitate disease transfer via flies?
2. Can a reduction in urban litter reduce pathogen and vector abundance (and disease burden)?
3. How do people interact with plastic litter and do they view it as a source of disease either through mosquitos or enteric diseases?
4. What are the socio-political obstacles for incentivising governments to remove peri-urban litter and increase sustainable waste disposal?

This interdisciplinary project will link environmental microbiology, waste management and disease ecology with sustainable development, public health and medical anthropology. The project will adopt methods and theories from both the natural & social sciences and will employ both qualitative & participatory approaches with a significant level of engagement with local communities. Field work will be carried out in Malawi and will focus on the peri-urban landscape of Blantyre. During two field seasons in Africa (each trip lasting between 4-5 months) the student will use a combined field and lab approach to (i) quantify the extent to which standing water associated with plastic waste supports populations of mosquitoes (identified by both molecular approaches and identification of larval stage); (ii) conduct a series of controlled laboratory ‘choice experiments’ to determine if mosquitoes preferentially oviposit in different types (e.g. polyethylene, polyethylene terephthalate, polystyrene), colours or sizes of typical plastic wastes in the urban environment, together with an assessment of the associated larval survival; and (iii) determine the potential for flies to spread disease from different categories of plastic litter. Spatial and statistical analysis will correlate mosquito/fly abundance with particular litter types, and this information will be used to develop a GIS-assisted landscape epidemiology model (created in the integrated ArcGIS platform), that will also incorporate data on community health, e.g. from clinical reports of malaria and diarrhoeal diseases. Peri-urban drainage systems & sanitation facilities will also be mapped, and the ‘blockage potential’ from rubbish and wastes quantified in terms of increased standing water. In addition, following rain events mosquito larvae will be identified in litter-associated standing water over the subsequent days. A participatory ethnographic approach, drawing on a combination of semi-structured interviews, focus group discussions and participant observation, will be used during fieldwork to understand how local rural communities interactive with waste, and perceive issues of plastic waste and the impact on human health, and how they might be incentivised to adopt strategies that decreases plastic waste in the community by a greater knowledge of how disease interacts with plastic waste disease burden.

Timeline – Year 1
Following a critical review of the literature (months: 0-4), the student will undertake a short ‘Problem-framing’ field mission to Blantyre to identify key stakeholders and begin the design of pilot experiments. Back in the UK, the student will attend a range of training courses plan and design (incl. ethics and risk assessments), the experiments for the next field mission
Timeline – Year 2
During an extended fieldwork mission, the student will undertake an intensive series of field experiments complemented by laboratory mesocosm experiments to quantify the effects of plastic waste on vector dynamics.
Timeline – Year 3
During the final field visit, in addition to completing ecological fieldwork, the student will also conduct surveys to understand the perception of plastic waste in the community, and organise and lead a workshop with local stakeholders to disseminate the finding from the whole project
Timeline – Year 3.5 (6 months only)
The student will co-develop a policy brief for governmental regulators and the remaining time will be spent writing up the thesis and papers for publication

Training & Skills
The student will benefit from becoming part of the SPACES team. The SPACES project is a ca. £3.5 million GCRF project focused on understanding the impacts of plastic waste on human health in East and Southern Africa. This studentship will provide a platform to build an interdisciplinary research career in sustainable development and public health. Extensive skill development in field work will include comprehensive training in sampling & monitoring techniques, while the student will also benefit from working closely with experienced field researchers in Africa. The studentship will broaden the scope of the applicant’s skills base by providing specialist training in the identification of vectors and the safe handling of pathogenic microorganisms. The student will develop broad expertise in the environmental sciences, including microbiological techniques and GIS modelling methodologies, together with skills in the social and anthropological sciences & applied geography.

Integrating the safe and sustainable management of wastewater into small-scale vegetable production systems in Malawi

Professor Richard Quilliam

Worldwide, more than 800 million farmers are engaged in urban agriculture. Of these, about 200 million practice market-oriented farming, and often have no other choice but to use wastewater for irrigation [in this proposal we refer to ‘wastewater’ as the use of raw, partly treated, or diluted wastewater, from predominantly domestic sources]. Urban and peri-urban farmers in the developing world can enhance household income by producing perishable crops such as leafy vegetables for sale in local markets. These farmers are crucial for providing a continual supply of vitamin-rich vegetables to the community, and it is estimated that urban farmers who irrigate their crops with wastewater supply about 60% of vegetables sold in African cities. Such production of fresh vegetables is fundamental for alleviating hidden hunger (the deficiency in micronutrients, vitamins and minerals in the diet); furthermore, urban farming can provide significant employment and economic opportunities. Farmers often prefer to use wastewater for irrigation as it provides a free source of nitrogen and phosphorus (and thus, less money spent on fertilisers), and can be more reliable or cheaper than other water sources. Effluent is often in large supply, and compared to groundwater in Malawi, is low in salinity and high in nitrogen. Consequently, it has now become common practice in Malawi for urban farmers to deliberately vandalise wastewater flow channels or drain covers to divert effluent into their vegetable gardens. However, sanitary wastewater contains a variety of human pathogens, such as viruses, bacteria, parasites and helminths (many of which are capable of survival in the environment long enough to be transmitted to humans), together with a risk from anti-microbial resistance (AMR) genes. Thus, farmers are exposed to relatively high concentrations of pathogens, and have an increased risk of enteric disease and infections with worms. Women, who provide much of the labour required to produce vegetables are particularly at risk; women also dominate in the marketing and retail process and are mainly responsible for preparing family meals, which creates the opportunity for transferring pathogens to family members and the wider community. The sale of contaminated vegetables and leafy greens in markets is therefore of significant public health concern and despite international guidelines for using wastewater in agriculture, this knowledge is poorly implemented at the local governmental level, and guidelines are rarely translated to local farmers.

Integrating the safe and sustainable management of wastewater with increased agricultural productivity has recently gained interest in many countries. Therefore, the overarching objective of this studentship is to involve local water management stakeholders, urban water users and agricultural wastewater user groups to provide an interdisciplinary framework for the student to integrate policy, health, environmental and engineering dimensions that cuts across traditional academic disciplines. Specifically, the research objectives of this project are to:
1. Create a ‘Stakeholder’s Alliance’ to provide an intersectoral forum to identify and integrate farmer’s and public health leader’s needs and concerns, while addressing food security and public health risks to people and the wider community
2. Map areas of wastewater irrigation within the Blantyre municipal area, and monitor the dynamics of water quality and subsequent contamination of vegetables at four case-study sites
3. Develop and test context-specific interventions (including assessment of the associated trade-offs) for reducing pathogen transfer from wastewater irrigation to vegetables and leafy greens
4. Trial innovative public awareness programmes to inform farmers and consumers of the potential health impacts of wastewater irrigation, and key targets for improved practice
5. Develop a ‘National Policy Framework’ to facilitate the safe use of wastewater in food production

Timeline (Year 1): Following a critical review of the literature (months: 0-4), the student will undertake a short ‘Problem-framing’ field mission to Blantyre and create an Alliance of key stakeholders to support co-design of the planned research activities to ensure that the research is both contextually appropriate and delivers for all stakeholders. Using our established networks via WASHTED at the University of Malawi, the student will enlist stakeholders from the water industry, the local government, the food industry, public health, town planning, local markets and consumer groups. In addition, the student will engage with local urban farmer groups and ensure appropriate representation of small-scale farmers and food producers within the Alliance. The Alliance will become a co-operative that provides the means for discussing options for addressing water quality regulations and water management challenges that both integrate farmer’s needs and concerns, whilst addressing public health risks to the wider community. It is anticipated that the student will bi-annually convene the Alliance for workshops/meetings and that the initiative will continue beyond the lifetime of the project, and thus support long-term real-world impact. Back in the UK, the student will attend a range of training courses plan and design (incl. ethics and risk assessments), the experiments for the next field mission
Timeline (Year 2): During an extended fieldwork mission, the student will use satellite images, local information and knowledge from the Alliance to map all areas of wastewater irrigation in the Blantyre municipal area. This will provide data on the extent and spatial distribution of wastewater use. The student will use four case study sites (as agreed within the Alliance) to quantify the dynamics of temporal water quality used for irrigation (e.g. E. coli, faecal coliforms and helminth eggs) and subsequent contamination of vegetables and leafy greens. In addition, transport and sale points of vegetables will be mapped to identify high-risk markets and consumers.
Timeline (Year 3): The student will, develop and test context-specific strategies for reducing pathogen transfer, and test the feasibility of strategies to reduce pathogen transfer to vegetable crops (e.g. natural de-contamination from cessation of irrigation, sedimentation ponds, adaptive irrigation methods, activated charcoal), by utilising a citizen science approach among farmers to ensure these methods are fit for purpose. The student will also co-develop an awareness programme with the Stakeholder Alliance (e.g. using a variety of media and social media outlets, radio interviews, posters, workshops) that promote guidelines (e.g. in the form of a simple risk assessment matrix) for farmers and consumers about the potential health impacts of wastewater irrigation. A context-sensitive approach will be used that considers gender, illiteracy and the limited time farmers have available to engage with such programmes.
Timeline (Year 3.5): The student will co-design a strategic ‘National Policy Framework’ with the Stakeholder Alliance that can be translated to other areas in Malawi, and scaled-up to countries where there are similar management pressures to use wastewater resources to increase food security. The remaining time will be spent writing up the thesis and papers for publication.

Training & Skills:
This studentship will provide a platform to build an interdisciplinary research career in sustainable development and public health. The student will develop broad expertise in the environmental sciences, together with skills in the social sciences & applied anthropology. Extensive skill development in fieldwork will include comprehensive training in sampling & monitoring techniques, while the student will also benefit from working closely with experienced field researchers in Africa.


We are always keen to hear from potential PhD students, post-doctoral researchers or visiting academics who would like to come and work with our research group at Stirling, particularly if you have already secured your own funding.

To get in touch, please either view the advertised opportunities, or explore the team pages linked below and contact the person who you would like to work with directly.

Professor Richard Quilliam
Dr David Oliver
Dr Heather Price
Dr Jennifer Dickie