A team of 25 international scientists has proposed a strategy to prevent future pandemics by conserving natural habitats and promoting biodiversity. The plan seeks to ensure sufficient food and space for the disease-harbouring animals to limit contact and transfer of pathogens to humans.
“The world is focused on how can we detect and then contain a novel pathogen once it is circulating in humans, rather than how can we prevent that pathogen from entering the human population in the first place,” says Raina Plowright, Professor in the Department of Public and Ecosystem Health in the College of Veterinary Medicine, Cornell University, and first author of the paper ‘Ecological countermeasures to prevent pathogen spillover and subsequent pandemics’. The paper was published in Nature Communications recently.
Reducing the risk of pandemics needs steps in prevention, preparedness and response. When preparedness and response get focus, the prevention, especially the prevention of zoonotic spillover, has been neglected. The scientists elucidate the mechanism linking environmental change and zoonotic spillover using spillover of viruses from bats as a case study.
In most of the cases, pandemics begin when disease-harbouring animals, such as bats, come in close proximity to people, livestock or other animals and pass on new pathogens. Viruses such as SARS-CoV-2, SARS-CoV-1, Nipah, Hendra and possibly Ebola have all fatally spilled over from bats to humans, sometimes through an intermediate host.
The prevention strategy of the team is based on the findings from two studies conducted in 2022 about how bats can spread fatal Hendra virus to horses and people. When bats lose their natural habitats, their large groups splinter and migrate in small groups to agriculture lands and migrant areas. When they are stressed, they shed more virus in their urine. When the horses graze on the ground where the urine falls, they get infected. Humans get infected from the horses. This explains the link between environmental changes and spillover of pathogens from animals to humans.
The study emphasizes the importance of conservation of natural habitats and calls for policy frameworks to break the chain of transmission of pathogens.
“While public health officials have been focused on biomedical research, only a handful of ecological studies exist that explore drivers of spillover and what stops it. Ecological solutions are the only long-term solution to address the issue. The study identifies ecological interventions that can disrupt the spillover mechanisms and proposes policy frameworks, both international and national, as prevention strategies,” Dr. Nameer P.O. Dean, College of Climate Change and Environmental Sciences, Kerala Agricultural University, who is part of the Scientist team, points out.
Land-use changes, which put people in closer contact with animals, are a prominent driver for pathogen spillover into people from wildlife. As the studies revealed, without intact habitat, animals become stressed and shed more virus and they move in search of food towards agricultural and urban areas.
The scientists stress that the key ecological intervention that disrupts the mechanisms for spillover is to protect places where animals eat. Efforts should be made to make sure there’s always an abundant supply of food available at all times of year, especially when animals are in stressful conditions like reproduction and migration. It is important to protect the natural habitats, where animals may roost or aggregate in large numbers. Protecting lands that act as buffers between people and wildlife is also key. They also stress the importance of protective measures for communities, which closely interact with wildlife, to minimise pathogen exposure.
The team highlights the need for an international agency or panel that can assess and synthesize data on pandemic prevention, preparedness and response and collect metrics on intactness of landscapes, ecological integrity and biodiversity.
