It’s not just humans and animals that are affected by emerging diseases. In this latest addition to the On the Horizon series, we learn about a poorly understood bacterium that causes significant hardships to farmers across the world.
The Apulia region, a thin strip of southeast Italy that stretches out into the Ionian and Adriatic Seas, is home to millions of olive trees, some of which are over a thousand years old. Around 2010, some of these ageing trees began showing signs of serious disease, with scorched and dying leaves. By 2013, over 8,000 hectares had been affected. Researchersshowed that these plants were infected by a bacterial pathogen that hadn’t previously been detected in the European Union: Xylella fastidiosa.
X. fastidiosa is transmitted through the bites of insects that feed on the sap within a plant’s water transport network. Once infected, the bacteria colonise this system of tubes, known as xylem, forming biofilms that prevent water and nutrients travelling from the roots to the leaves, sometimes killing the plant.
Antimicrobial-resistant infections are an increasing global threat, serious enough that in July 2014 the then-UK Prime Minister David Cameron asked Lord Jim O’Neill to lead a major independent Review on Antimicrobial Resistance, to analyse the global challenges posed by antimicrobial resistance (AMR) and to propose international solutions to tackle the problem.
Two years on, the Review has published several reports addressing different aspects of the AMR challenge and set out its final recommendations. These outputs have regularly featured in the news, and the team has engaged broadly with experts and stakeholders internationally, including governments, multilateral bodies like the World Health Organization, academia, industry and healthcare providers. Anthony McDonnell, Head of Economic Research for the Review on AMR, joined us for last month’s Policy Lunchbox event to discuss the Review’s work.
To help change behaviour and illustrate the seriousness of AMR, the Review drew on existing evidence showing that drug resistance is already a global problem. Importantly, they also used economic models to predict and outline future global costs if no action was taken. The headline figures from this work – that AMR could cause 10 million deaths a year and a cumulative economic cost of $100 trillion US by 2050 – have been very widely cited.
Quoting statistician George E. P. Box’s “all models are wrong but some are useful”, Anthony acknowledged that these simplified models are imperfect, but important for stimulating interest and debate. In reality, the models likely underestimate the potential impacts of AMR because they used a selection of key infections and ignored many secondary impacts, such as lost productivity from increased sick leave and greater risks associated with routine medical treatments.