In its 2024 report, the WHO listed more than 30 pathogens that could cause the next pandemic.

Even though the world seems to have moved forward, there are occasional events that remind us that the new coronavirus has not disappeared. More than 40 athletes will compete in the 2024 Paris Olympics. The test came back positive.On August 6, the World Health Organization (WHO) highlighted the increasing number of new global infections, and the Sarbecovirus subgenus, which includes SARS-CoV-2, is now on the “priority pathogens” list in the WHO's recently published “Pathogens Prioritization” report.

The report, a research readiness framework for epidemics and pandemics, is the result of work launched in late 2022 and involved more than 200 scientists from 54 countries who assessed evidence relating to 28 virus families and one core bacterial group, including 1,652 pathogens. The final list includes more than 30 “priority pathogens”.

Sarbecoviruses are classified as “high” on the WHO list due to their elevated risk of causing a Public Health Emergency of International Concern (PHEIC). This list also includes the Sarbecovirus subgenus, which includes Middle East Respiratory Syndrome coronavirus (MERS-CoV). MERS-CoV and the Severe Acute Respiratory Syndrome (SARS) virus were also listed in WHO reports in 2017 and 2018, but not the entire subgenus.

The list of priority pathogens is also not new, as another virus India has been dealing with recently – the Nipah virus. A 14-year-old boy died He died after contracting the infection at the Government Medical College Hospital in Kozhikode, Kerala. Ebola and Zika virus are also on the list, as they were in 2018, and both are classified as 'high' risk of a Public Health Emergency of International Concern (PHEIC). Maharashtra is currently suffering from a Zika virus outbreak, and reports suggest that Over 70 Zika cases in Pune in last two months Among them are 26 pregnant women.

Imagine that scientists and public health officials are individuals searching for the “lost key” (the next pandemic pathogen). The areas lit by “streetlights” represent priority pathogens. The illuminated area can be expanded a bit by studying prototype pathogens and using them as pathfinders within the family to broaden our knowledge and understanding. Ignoring the “dark areas” is not advisable, as there is uncertainty about which pathogen will actually cause the next PHEIC or pandemic. | Photo credit: WHO, Pathogen Prioritization, June 2024 report

The priority pathogens list identifies pathogens to which governments can allocate resources for surveillance and medical response, said Subramanian Swaminathan, a Chennai-based infectious disease expert. This doesn't mean that all pathogens are currently a problem, he said, but it does mean that countries should monitor those that have the potential to become a problem.

“Surveillance of these pathogens involves monitoring multiple aspects such as whether they are spreading across geographic regions, whether they are becoming more virulent or transmissible, whether the clinical manifestations of the disease they cause are changing, whether they are becoming more resistant to known treatments, or whether they have the ability to evade vaccines,” he says.

New additions to the list are dengue virus and influenza A virus. H5 subtype caused bird flu outbreak The virus, which originated in India and has also affected cattle in the United States, is currently Eruption in part of Africa.

Among the bacteria added to the list are those that cause plague, cholera, pneumonia, dysentery and non-typhoidal Salmonella, a major cause of diarrheal disease.

Earlier this year, WHO has updated the Bacterial Pathogen Priority List (BPPL). This included gram-negative bacteria resistant to last resort antibiotics and tuberculosis bacteria resistant to the antibiotic rifampicin. The list included 15 families of antibiotic-resistant bacteria.

According to the report, in the Southeast Asian region, bacterial pathogens such as Vibrio cholerae O139 (cholera) and Shigella serotype 1 (dysentery) are priority pathogens. Priority pathogens Henipavirus nipahense (Nipah virus) and Bandavirus dabiense (causing severe febrile thrombocytopenic syndrome) are endemic, as are the mosquito-borne dengue (dengue fever) and Zika virus infection (Zika virus infection), and the chikungunya alphavirus.

Priscilla Rupali, senior professor and head of the infectious diseases department at Christian Medical College, Vellore, says resources need to be focused on diseases with high mortality rates that can lead to pandemics, such as cholera, Nipah, dengue and Zika. For other diseases that cause significant morbidity, such as chikungunya and shigella, surveillance to predict outbreaks is important, Rupali said.

The report lists diseases such as Nipah, Zika and dengue that India is already aware of and tackling, according to Abdul Gafur, an infectious diseases consultant at Apollo Hospitals in Chennai. “What's needed is more data and research, but most importantly, more low-cost diagnostics for priority pathogens. The Indian government needs to support start-ups developing diagnostics for these pathogens,” he says.

Prototype pathogen

For the first time, the 2024 report incorporates the concepts of a “family approach” and “prototype pathogens.” The family approach is important, Dr. Swaminathan said, because pathogens within a family have many similarities and even share genetic material, existing treatment options and vaccines for one strain of a pathogen family may be repurposed for another. “By prioritizing the study of entire pathogen families rather than a few individual pathogens, this strategy enhances our ability to respond efficiently to unknown threats such as unexpected variants, emerging pathogens, zoonotic infections, and 'pathogen X,'” the report states.

According to the report, a “prototype pathogen” is “a representative pathogen within a family that is selected as a model for basic research” to develop medical countermeasures that can be applied to other members of the family.

As the report points out, the global health situation is constantly changing, with the potential for the emergence of new pathogens and the evolution of the threat level of existing pathogens, highlighting the vital importance of investing in research, development and innovation on an international scale.

For the complete report, click here.

(Zubeda.h@thehindu.co.in)