A Transformative Technology Platform for Interrogating Airborne Adaptation of Respiratory Pathogens

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Aerosols are everywhere in the atmosphere, ranging in size from the very small nanometre-sized particles produced by cars through to larger water droplets in clouds with diameters similar to that of a human hair. Not only can pollution particles lead to increased rates of morbidity and mortality, but they can also act as a means of transporting bacteria and viruses, facilitating disease transmission. Indeed, infectious diseases are spread by the airborne route through aerosol droplets produced by the human body and expelled through coughing and sneezing. Such events account for some of the deadliest infectious diseases, including tuberculosis (TB), severe acute respiratory syndrome (SARS) and bacterial meningitis, all of which have a major impact on our society. Despite the significant health and financial burdens that arise from the airborne transmission of pathogens, studying bacteria and viruses in the aerosol phase remains challenging as few measurement techniques exist to explore the changes in viability and infectivity that may occur during airborne transport. In the proposed research, we will develop a novel instrument for exploring the processes that affect how well bacteria survive when in airborne droplets. In particular, we will build and test an instrument that will allow the suspension and manipulation of aerosol particles in air containing a known number of bacteria. For example, we will develop an approach to generate individual droplets that mimic our coughs and sneezes, each containing a known number of bacteria. By subtly manipulating each droplet, we will be able to catch and levitate them in an electric field for any amount of time. We will then, in a controlled way, deposit the droplets into a dish containing suitable conditions to allow any bacteria present to grow. Whilst airborne, we will be able to change the temperature and humidity of the environment experienced by the droplets. We will also expose them to light (similar to sunlight) and also to typical atmospheric chemicals like ozone. Combined, these capabilities will allow us to simulate the processes the bacteria experience whilst moving from person-to-person. Thus, we will be able to measure how different environmental conditions influence how many bacteria remain alive at different time points. Once the instrument has been built and tested, we will study a bacterium (Neisseria meningitidis also known as meningococci) which causes blood and brain infections but can be spread from person to person by coughing and sneezing. We will measure the airborne survival of meningococci at different times, temperatures and humidities, with conditions representative of cold-wet or cold-dry environments to simulate winter day conditions typical of the UK, or hot-dry conditions typical of the Africa dry season. These conditions represent seasons when the disease rates are highest in both regions. Finally, we will combine droplet capture with an exciting new instrument, the NanoString, which can measure how bacteria change in ways which could make them more or less able to cause disease. Together, the capabilities to measure not only how long bacteria survive but how they change outside of our bodies will help us to use mathematics to better model risks of disease spread, and also to identify novel better means of preventing person-to-person infection by aerosol (airborne) transmission.