Monitoring presence and distribution of vectors and pathogens with eDNA
Exploring the strength of environmental DNA (eDNA) in monitoring presence and distribution of vectors and pathogens of medical and veterinary importance.
Monitoring occurrence and density of pathogens and vectors in the environment facilitates detections that are important as a proxy for infection of host organisms in connected and shared habitats. For example, both mosquito and snail vectors utilize aquatic habitats which are also shared by humans in poor countries. Since multiple vectors and pathogens, some of which are zoonotic occur in the environment, a monitoring technique that embraces a One Health approach is appropriate.
Tanzania is still using conventional bio-monitoring approaches for pathogens and vectors monitoring, which mainly rely on symptomatic cases and morpho-taxonomic identification. However, these approaches delay outbreak detection and are laborious, and time consuming to apply in the field because they are low-throughput and lacks sensitivity. Active cercarial shedding assay is often used to monitor snail borne diseases. Nevertheless, not all snails that harbour patent and prepatent parasites actively shed cercariae, which may lead to false conclusion. Alternatively, animal or human faecal and urine samples are collected for egg microscopy screening. However, this method usually misses up to 20 to 30 percent of active infections.
Larval sampling and morphological identification are used for mosquito monitoring. However, accurate morphological identification of mosquito larvae to species level becomes very difficult when specimens are too damaged. Also, most identification keys are for 4th instar larvae; hence, identification of younger larvae is difficult. Likewise, mosquito habitats are species specific, it is therefore difficult to accurately identify the key habitats of each species in a large area, especially at younger stage.
Fortunately, all these challenges can be addressed through environmental DNA-based monitoring. eDNA is a novel approach that has been recently shown to offer a promising alternative for monitoring and early detection of pathogens and vectors in the environment before disease outbreak and without collection of specimens. eDNA can also be used to infer ecological responses to human degradation impacts and restoration efforts even on a short, seasonal periods of time, and thus help document the dynamic response of biodiversity to impact and remediation.In this project we will explore the impact of eDNA technology for simultaneous monitoring of the presence and distribution of multiple pathogens and vectors in the environment as a proxy for human and animal likely infection, under the “One Health” framework and changing microclimate and land use in Tanzania.
The project will address how sequencing eDNA from water samples can revolutionize the conventional monitoring methods, and provide the innovative, reliable, and rapid solutions to the challenges faced by conventional parasite and vector monitoring methods and thus enable a more comprehensive understanding of the spatiotemporal dynamics of vectors and disease agents. The project will focus on mosquito and snail borne pathogens in northern Tanzania where they have high prevalence in the country.
Contact information
Gordian Mataba