Preparing for Disease X: lessons from the frontline

Zoonotic diseases, which originate in animals and spread to humans, are becoming an increasing threat to global health security. Laura Hucks, technical director for global health at Mott MacDonald, speaks to our regional experts in Asia and Africa about the challenges of containing these infectious diseases.

Disease X is the ominous title given to an unknown pathogen with pandemic potential. It appears at the bottom of the World Health Organisation’s (WHO) list of priority diseases for urgent research and development.

Although its identity is unknown, it’s becoming increasingly likely that Disease X will be a zoonotic disease, an infectious disease affecting humans that originates in animals. Over the past three decades, about 75% of emerging infectious diseases affecting humans have been zoonotic.

This highlights the urgent need to address the connections between human, animal and environmental health – a core principle behind the One Health approach.

The growing threat of zoonoses

Zoonotic diseases pose a persistent and evolving public health threat. Most diseases on the WHO’s list of priority diseases are zoonotic in origin, including COVID-19, Ebola, Marburg, Zika and SARS. Yet global investment in the workforce, infrastructure and systems required to manage zoonotic disease remains woefully inadequate.

Our team of global health experts understand the risk of zoonoses and use a One Health approach when advising on health system resilience and addressing complex infectious disease challenges in a range of different contexts.

Professor Stanley Fenwick, a leader in the field, has examined the interplay between human and animal health for over 20 years. He defines One Health simply as “the interconnectedness of human, animal and environmental health, recognising problems in one area can impact the others”.

Currently, Fenwick is part of our international health team supporting the Fleming Fund, a UK aid funded initiative tackling antimicrobial resistance (AMR) across 23 countries in Asia and Sub-Saharan Africa. AMR is a slow-moving ‘silent pandemic', which exemplifies the One Health challenge. Drug-resistant pathogens circulate among humans, agriculture and the environment, threatening the efficacy of antibiotics, endangering food security and impacting ecosystems.

On the frontline: response and research

For our One Health specialists based in Africa and Asia, understanding the intricate relationships between humans, animals and the environment is critical to effective disease control in low-resource settings. Although the One Health concept is easily defined, putting the approach into practice is more challenging.

Winifred Amia, a member of our team based in Uganda, first encountered the term One Health when studying veterinary medicine in the country’s capital Kampala. In 2019, Amia was part of a team responding to a plague outbreak in the West Nile region of Uganda. They swiftly mobilised diagnostic testing, identifying that an outbreak in neighbouring Democratic Republic of Congo had spread into Uganda. The capacity to recognise zoonotic transmission enabled a rapid response, helping contain the disease and minimise its spread.

Another of our health specialists in West Africa, Nigerian epidemiologist Mathias Besong, advocates for proactive screening of humans and animals for both priority and novel diseases. During Nigeria’s yellow fever outbreak in 2017 – the first in 21 years – Besong found low vaccination levels amongst the affected population coupled with the presence of yellow fever-carrying mosquitos in the outbreak area.

Zoonotic viruses, like yellow fever, can circulate between animals and mosquitoes for months before outbreaks occur in human populations. Besong says “there is an urgent need for improved surveillance at the human-animal-wildlife interface, especially in West Africa where there is limited diagnostic capacity”.

In southeast Asia, high levels of biodiversity and dense human populations create an acute potential for zoonotic transmission. Etienne Chevanne, a member of our team based in Bangkok, has seen widespread adoption of the One Health approach, unlocking new opportunities for multisectoral collaboration and research.

Chevanne experienced this first-hand when investigating human and canine leptospirosis, an underdiagnosed and neglected disease in Myanmar. He set up dialogue platforms for human and animal health professionals and supported capacity building efforts for curbing leptospirosis. He says there is “no way we can address zoonotic threats by working in silos”.

Preparing for the next pandemic

While COVID-19 raised global awareness of pandemics and the importance of preparedness measures, our experts warn that zoonotic spillovers are unlikely to diminish. Poverty, food insecurity, climate change, environmental degradation and migration continue to bring humans and animals closer together, increasing the risk of further outbreaks.

Addressing zoonotic diseases demands connected thinking, creativity and investment. For Fenwick, the growing strength of the quadripartite alliance, which comprises the Food and Agricultural Organisation, United Nations Environment Programme, WHO and the World Organisation for Animal Health, is a sign of optimism. It facilitates high-level, equitable dialogues between global human, animal and environmental health leaders.

Fenwick emphasises that governments must “recognise the importance of a well-resourced, well-managed One Health approach and fund it accordingly”. This involves improving communication with the wider population about emerging zoonotic diseases, mandating multisectoral collaboration and information sharing, increasing epidemiology training across all sectors and integrating data collection and monitoring across sectors to inform changes in policy and practice.

Elevating the role of One Health experts is a crucial part of shaping effective health security policies and practices and allocating resources appropriately.

The One Health approach is not merely a conceptual framework that will help us ‘if’ we face another pandemic. It’s a vital strategy we will need ‘when’ the next global health threat hits us.