Disease X may cause serious worldwide pandemic: WHO

World Health Organization (WHO) has released the list of pathogens to prioritize for research and development in public health emergency contexts.A new addition to the original list released in December 2015 is a mysterious disease,"Disease X." that could cause a worldwide pandemic. Disease X may be caused by a pathogen currently unknown to human beings.A special tool developed for the purposes of the R&D by WHO shall identify those diseases that pose a public health risk because of their epidemic potential and for which there are no, or insufficient, countermeasures. The diseases identified through this process are the focus of the work of R& D Blueprint. This is not an exhaustive list, nor does it indicate the most likely causes of the next epidemic.The list is developed by a global team of experts in scientific, medical, and regulatory roles and the roadmaps for each disease will be published for wide dissemination.

The first list of prioritized diseases was released in December 2015 which was first reviewed in January 2017.Each year, the WHO identifies diseases for which there are no or insufficient countermeasures and that pose a public health risk because of their potential for causing an epidemic. Those diseases become the focus of the work of the R& D blueprint.The second annual review occurred 6-7 February 2018. Experts consider that given their potential to cause a public health emergency and the absence of efficacious drugs and/or vaccines, there is an urgent need for accelerated research and development for*:

• Crimean-Congo haemorrhagic fever (CCHF)


• Ebola virus disease and Marburg virus disease


• Lassa fever


• Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS)


• Nipah and henipaviral diseases


• Rift Valley fever (RVF)


• Zika


• Disease X

Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease, and so the R&D Blueprint explicitly seeks to enable cross-cutting R&D preparedness that is also relevant for an unknown “Disease X” as far as possible.

A number of additional diseases were discussed and considered for inclusion in the priority list, including Arenaviral hemorrhagic fevers other than Lassa Fever; Chikungunya; highly pathogenic coronaviral diseases other than MERS and SARS; emergent non-polio enteroviruses (including EV71, D68); and Severe Fever with Thrombocytopenia Syndrome (SFTS).

These diseases pose major public health risks and further research and development is needed, including surveillance and diagnostics. They should be watched carefully and considered again at the next annual review. Efforts in the interim to understand and mitigate them are encouraged.

Although not included on the list of diseases to be considered at the meeting, monkeypox and leptospirosis were discussed and experts stressed the risks they pose to public health. There was agreement on the need for: rapid evaluation of available potential countermeasures; the establishment of more comprehensive surveillance and diagnostics; and accelerated research and development and public health action.

Several diseases were determined to be outside of the current scope of the Blueprint: dengue, yellow fever, HIV/AIDs, tuberculosis, malaria, influenza causing severe human disease, smallpox, cholera, leishmaniasis, West Nile Virus, and plague. These diseases continue to pose major public health problems and further research and development is needed through existing major disease control initiatives, extensive R&D pipelines, existing funding streams, or established regulatory pathways for improved interventions. In particular, experts recognized the need for improved diagnostics and vaccines for pneumonic plague and additional support for more effective therapeutics against leishmaniasis.

The experts also noted that:

• For many of the diseases discussed, as well as many other diseases with the potential to cause a public health emergency, there is a need for better diagnostics.


• Existing drugs and vaccines need further improvement for several of the diseases considered but not included in the priority list.


• Any type of pathogen could be prioritised under the Blueprint, not only viruses.


• Necessary research includes basic/fundamental and characterization research as well as epidemiological, entomological or multidisciplinary studies, or further elucidation of transmission routes, as well as social science research.


• There is a need to assess the value, where possible, of developing countermeasures for multiple diseases or for families of pathogens.

The impact of environmental issues on diseases with the potential to cause public health emergencies was discussed. This may need to be considered as part of future reviews.

The importance of the diseases discussed was considered for special populations, such as refugees, internally displaced populations, and victims of disasters.

The value of a One Health approach was stressed, including parallel prioritization processes for animal health. Such an effort would support research and development to prevent and control animal diseases minimizing spill-over and enhancing food security. The possible utility of animal vaccines for preventing public health emergencies was also noted.

Also, there are concerted efforts to address antimicrobial resistance through specific international initiatives. The possibility was not excluded that, in the future, a resistant pathogen might emerge and appropriately be prioritized.