Study estimates over 9% of world's lands at high risk of animal-to-human infections

New Delhi: Over nine per cent of the world's land area is at "high" or "very high" risk of a zoonotic outbreak -- triggered when an infection spreads from an animal to a human or vice versa, such as the Covid pandemic, according to a study.

Findings published in the journal Science Advances also estimate 3 per cent of the global population to be living in extremely risky areas, and about a fifth in medium-risk areas.

Researchers, including those from the European Commission's Joint Research Centre (JRC) Scientific Development Programmes Unit in Italy, analysed location-specific information from the 'Global Infectious Diseases and Epidemiology Network' dataset and the World Health Organization's (WHO) list of diseases prioritised according to their potential for causing an epidemic or a pandemic.

Covid, Ebola, coronavirus-related MERS and SARS, and Nipah are among the most prioritised infections in the WHO's list.

The team's analysis suggests that conditions driven by climate change -- higher temperatures and rainfall, and water shortage -- elevate the risk of zoonosis, or 'spillover events'.

The study "presents a global risk map and an epidemic risk index that combines countries' specific risk with their capacities for preparing and responding to zoonotic threats (excluding SARS-CoV-2)." "Our results indicate that 9.3 per cent of the global land surface is at high (6.3 per cent) or very high (three per cent) risk," the authors wrote.

They also estimated about 7 per cent of Asia's and 5 per cent of Africa's land area to be at high and very high risk of outbreak, following Latin America (27 per cent) and Oceania (18.6 per cent).

Overall, the authors found that climate-related changes to the environment substantially drove a region's vulnerability to the risk of a spillover event.

They wrote, "This underscores the need for continued monitoring and the integration of climate adaptation and mitigation efforts into public health planning." "Translating these risk estimates into an epidemic risk index allows for the identification of high-risk areas and supports policymakers in improving response capacities, allocating resources effectively, and fostering international collaboration to address global health threats," the team said.

A study by the Indian Council of Medical Research found that over 8 per cent of outbreaks reported between 2018 and 2023 under the country's infectious disease surveillance system were zoonotic. Of a total of 6,948 outbreaks analysed, 583 (8.3 per cent) were spread to humans from animals.

Outbreaks were also found to consistently peak during June, July, and August. The findings were published in The Lancet Regional Southeast Asia journal in May this year.