What do I do?
A brief rundown on what I’m up to.
Scope
I thought it’d be a good idea to give an overview of my PhD project, and go into a little bit of detail about the background and importance of the work.
Public engagement is crucial part of the scientific process, and so this blog post will be aimed at a broader audience and written in plain English, to be as inclusive and accessible as possible.
NB: This can be tricky, so if there’s a part that could benefit from rewriting, please let me know.
Intro
Malaria is a disease, caused by the Plasmodium family of parasites and transmitted by mosquitoes belonging to the Anopheles genus. It causes debilitating symptoms, which include fever, vomiting, headaches, etc. and in serious cases can result in jaundice, seizures and death.
Great achievements have been made in the global health effort to control malaria, since 2000 ~660 million cases of malaria have been averted, due to vector control methods.
What is a vector?
Vectors are organisms that carry and transmit infectious disease pathogens (things that cause disease). The idea of vector control is that if we can control the vector we can control the disease it transmits.
Insert Bhatt fig here
Vector control for malaria relies on reducing the number of mosquitoes and reducing human exposure to mosquitoes. The two classic examples of this are insecticide-treated bed nets and indoor residual spraying.
Insecticide-treated bed nets provide a physical barrier while the occupant is sleeping and prevents contact with potentially infectious mosquitoes. Additionally, it also kills mosquitoes that land on the net, reducing the number of mosquitoes in the population.
Indoor residual spraying involves spraying the interior walls of houses with an insecticide compound. The reasoning being that when a mosquito is seeking a blood meal at night, it will be exposed to a lethal dose when resting on walls and die before biting a human.
Despite the great success in reducing its burden, malaria still claims roughly 500,000 deaths per year. This is a great concern for global health and is compounded by resistance to the insecticide compounds used to treat bed nets and spray walls. There is a concern that the failure of public health insecticides will lead an increase in malaria cases.
My work is within the lab of Professor Martin Donnelly, where the key focus is understanding the genetic components of resistance to insecticides. Understanding the genetic landscape, evolutionary history and the genetic fitness of resistant mosquitoes helps to inform vector control monitoring, tool development and intervention deployment.
The Malaria Mosquitoes
There exist a number of mosquitoes that are capable of transmitting malaria, some only to humans, some only to animal and some to both. My work focusses on two major humans mosquito vector species, Anopheles gambiae s.s. and Anopheles arabiensis.
These mosquitoes belong to the same complex of mosquito species, which are near visually identical, but differ in their genetics and behaviour. These two species are only relatively recently diverged at a common ancestor. As such, both An. gambiae s.s. and An. arabiensis exhibit a kind of porous barrier to their isolation as species. The upshot of this is that hybrids between the two have the chance to be fully fertile, where typically they would not be, just as with a Mule.
Fertile hybrids are interesting because they can allow gene flow from one species to the other, when the hybrid mates with a member from one of its parent species. From a global health perspective, this could mean that a mutation which allows mosquitoes to survive exposure to insecticide could possibly be transferred from one species to another.
This is where my PhD comes in. My PhD project is focussing on characterising the introgression events between An. gambiae and An. arabiensis and discussing the impact on global health methods employed to control malaria.
The Data and the Anopheles gambiae 1000 Genomes Project
I am very fortunate to be working with partners of the Ag1000G projects throughout my PhD.
Ag1000G is an international collaboration using whole genome deep sequencing to provide a high-resolution view of genetic variation in natural populations of Anopheles gambiae, the principal vector of Plasmodium falciparum malaria in Africa. – Anopheles gambiae 1000 genomes project