The disease ecology of mosquitoes and plastic waste in Malawi

We are seeking a highly motivated individual to carry out PhD research in the fields of environmental health and sustainable development. The successful candidate will be based at the University of Stirling, supervised by Professor Richard Quilliam with Dr Chris Jones (Liverpool School of Tropical Medicine) and Dr Tracy Morse (Strathclyde University). The student will also become fully embedded within the SPACES project (https://www.stir.ac.uk/news/2020/november-2020/385m-stirling-led-study-to-tackle-impact-of-plastic-pollution-in-africa/) and the “Environmental Sustainability & Human Health Research Group” https://eshh-stirling.com/ at the University of Stirling. 

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. 

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)?

This interdisciplinary project links environmental microbiology, waste management and disease ecology with sustainable development, and public health. The project will involve 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.