Context: Disease X represents an unpredictable, novel threat that requires rapid global response and adaptation. This becomes significant due to increased interconnectedness of our world (with frequent international travel and trade), making it easier for localised outbreaks to escalate into pandemics, as seen with COVID-19.
Disease X?
- Disease X is not a specific disease but is the name given to a potential novel infectious agent. It represents an illness which is currently unknown but could pose a serious microbial threat to humans in the future.
- In 2018, the World Health Organisation (WHO) added Disease X to the ‘list of pathogens’ to prioritise preparation on the emerging diseases that do not yet have vaccines or drug treatments, and could give rise to a severe epidemic.
- It could originate from Pathogen X, which could be a virus, a bacterium, a parasite, fungi, helminths, or even a prion (a misfolded protein capable of causing severe neurological diseases).
WHO’s priority list of Pathogens:
- The list of pathogens is a strategic tool published by WHO in 2018 to focus global attention and resources on the most serious infectious disease threats.
- This list identifies diseases that have:
- High mortality rates
- Epidemic or pandemic potential
- Lack of adequate preventive (vaccine) or therapeutic options.
- The current list (not exhaustive ) includes: Ebola virus disease, Marburg virus disease, Lassa fever, Nipah virus, Rift Valley fever, Crimean-Congo haemorrhagic fever, Zika virus, Severe Acute Respiratory Syndrome (SARS), Disease X.
Significance: It helps policymakers, researchers, and health organisations prioritise efforts toward controlling the diseases (to guide research and development, allocate funding, and enhance preparedness).
Risk Factors for Disease X:
- Zoonotic Spillover: Increased risk of zoonotic spillover due to human encroachment on wildlife habitats, deforestation, and the intensification of agriculture.
- Since 1940, researchers have identified more than 300 emerging infectious diseases, about 70% of which have zoonotic origins (transmitted from animals to humans).
- Increasing Antimicrobial Resistance: Resistance acquired by any microorganism (bacteria, viruses, fungi, parasite) against antimicrobial drugs or treatments to which they were previously susceptible.
- Incomplete doses of medication, self-medication, inappropriate disposal of unused or expired medication in the environment.
- Using antibiotics in farm animals, herbicides may enrich AMR genes (ARGs) and Mobile genetic elements (MGEs) by altering soil microbiomes.
- Biofilms on microplastics and untreated solid and liquid waste can act as a reservoir of AMR microbes.
- Risk of Bioterrorism and Accidental lab leaks. Beyond the WHO’s guidelines, there is no universal law, regulation or international oversight mandating even basic requirements, such as external independent inspections of biosafety laboratories (which host a range of pathogens).
- Climate Change:
- Climate change is expanding the burden of infectious diseases (transmitted by insect vectors and through contaminated water). It is also pushing pathogens to adapt to new hosts and environments.
- With global warming there is a risk of thawing permafrost which harbours viruses up to a million years old (older than the human species).
Way Forward:
- Need for robust surveillance systems to detect new outbreaks early and global alliance for developing its treatment. E.g., Coalition for Epidemic Preparedness Innovations (CEPI) has set a target of 100 days to develop, test and produce a new vaccine against pathogen X (COVID-19 vaccine took 326 days).
- Investing in Research and Innovation: Utilising advances in genomic sequencing, artificial intelligence, and real-time data sharing as essential tools for developing diagnostics, therapeutics, and vaccines.
- Strengthening healthcare infrastructure particularly in low- and middle-income countries.
- Global Collaboration: Frameworks like the Nagoya Protocol (which ensure equitable sharing of benefits from genetic resources) could be expanded to include biological materials like pathogens. It would promote global collaboration, ensuring fair access to research and medical countermeasures during outbreaks.
Conclusion: While epidemiology cannot predict the exact moment or source of Disease X, it can help identify high-risk regions and behaviours. Governments must work together to share data, pool resources, and ensure equitable access to diagnostics, treatments, and vaccines.