I am an epidemiologist, parasitologist and mathematical modeller focusing on infectious diseases. I am part of the malaria modelling group at Imperial. Specifically I concentrate of the impact of transmission-blocking drugs and vaccines and vector control interventions against malaria. I have a broader interest in host-parasite dynamics, how the distribution of parasites and exposure rates vary across the animal kingdom, and what factors govern where individuals fall in that distribution
Malaria remains a serious public health concern. The malaria parasite is transmitted between vertebrate hosts by Anopheline mosquitoes. Transmission stages are ingested during blood-feeding and develop into oocysts on the wall of the mid-gut. Sporozoites are released from oocysts and gather within the mosquito salivary glands before being injected back to the vertebrate host during a subsequent feed. Within the host, the sporozoites pass from the blood to the liver where they encyst. On rupturing, tens of thousands of blood-stage parasites are released per cyst which go on to reproduce asexually. Some of these asexual parasites will develop into gametocytes that can complete the life-cycle on transmission back to a mosquito.
Transmission blocking vaccines
Transmission-blocking interventions (TBIs) aim to eliminate malaria by reducing transmission of the parasite between the host and the invertebrate vector. TBIs include transmission blocking drugs and vaccines which interrupt transmission by targeting sexual, sporogonic, and/or mosquito antigens. I work on a statistically robust empirical method for estimating TBI efficacy from population assay data which fits a hierarchical Bayesian model to multiple life stages of the parasite. This enables both host-to-vector and vector-to-host transmission to be a density-dependent process whilst accounting for stochastic fluctuations driven by superinfection and small sample sizes. Doing so increases the precision of intervention efficacy estimates to capture the impact of TBIs at suppressing parasite prevalence and density in secondarily infected hosts.
Mosquito control remains vital to the fight against malaria. Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) programmes has reduced the burden of disease globally and these interventions are key in the drive towards malaria elimination. Yet there is a growing realisation that the effectiveness of these tools is under threat. Investment in vector control in recent years has resulted in an increasing number of candidate compounds and methods for delivery. We aim to understand how these different ideas not only kill mosquitoes, but also contribute to protecting patients from reinfection, reducing malaria transmission and averting cases.
et al., 2019, Assessing local chlamydia screening performance by combining survey and administrative data to account for differences in local population characteristics., Sci Rep, Vol:9
et al., 2018, Systematic review of indoor residual spray efficacy and effectiveness against Plasmodium falciparum in Africa, Nature Communications, Vol:9, ISSN:2041-1723
et al., 2018, An inexpensive open source 3D-printed membrane feeder for human malaria transmission studies, Malaria Journal, Vol:17, ISSN:1475-2875
et al., 2018, Synergy in anti malarial pre-erythrocytic and transmission-blocking antibodies is achieved by reducing parasite density, Elife, Vol:7, ISSN:2050-084X