Vampire bats and mosquitoes: Combining surveillance and genomics to dissect the impacts of disease control in the field
Control interventions via lethal removal of animals that transmit pathogens between hosts is a widely implemented strategy against many human and animal diseases. However, animals behave differently to different types of interventions, and unforeseen demographic and behavioural responses can cause putative interventions to backfire. Long-term control therefore relies on understanding the underling mechanisms leading to the observed response of population reduction. Here, I explore this challenge in two systems: culling of vampire bats and use of insecticidal treated bednets against malaria mosquitos. Although vampire bats have been culled for over 50 years for rabies prevention, little is known of the ability of culls to reduce the burden of rabies and theoretical studies have suggested the possibility of counterproductive effects. Combining Bayesian state-space models and viral phylogeography we showed that a large-scale bat cull in Peru had negligible effects on spillover from bats to livestock and that culling bats can accelerate or stall viral spread to new areas depending on the epidemiological context. For malaria control, the bednet Olyset-DUO trialled in Burkina Faso was hypothesized to reduce mosquito populations through two different routes (reduction of adult survival and fecundity) but how it translated to wild populations was undetermined. Our results confirmed the expected demographic impacts but showed these were transient, leading loss of effectiveness. Together, these studies highlight how combining field surveillance with genomics approaches is essential to dissect the impacts of interventions on fitness and behaviour and can generate critical insights to avoid unanticipated counterproductive outcomes of interventions.
