Climate Change

Migration reduces transmission of pathogens between species: UN Report

The migration behaviours of several species is changing because of man-made factors like climate change and habitat loss  

By Ishan Kukreti
Published: Wednesday 08 July 2020

Migration undertaken by migratory species can reduce the spread of zoonotic diseases, said a report jointly released by the UN Environment Program (UNEP) and the International Livestock Research Institute (ILRI) July 6, 2020.

Migratory species like the Chinook salmon (Oncorhynchus tshawytscha), green sea turtle (Chelonia mydas), western toad (Anaxyrus boreas) and the flying fox (Pteropus vampyrus) are associated with the spread of zoonoses (illnesses caused by germs spread between animals and humans).

The reduction of length or suppression of the migration of such species was associated with an increased load in pathogens, the report pointed out.

“Their migration has shown to reduce transmission in some species,” said the report titled Preventing the Next Pandemic: Zoonotic disease and how to break the chain of transmission.

The migration behaviours of several species, however, changed due to man-made factors like climate change and habitat loss.

The conservation status of many migratory species declined worldwide, with habitat loss being a primary factor.

“Many factors related to the increased occurrence of zoonotic diseases are the same as those that threaten the survival of migratory species,” the report said.

The loss of ecological connectivity — vital for migratory species — is of particular concern as well.

“Maintaining healthy, well-connected ecosystems is important for migratory species and also should help reduce the prevalence of infectious diseases,” the report suggested.

There is an increase in viruses emerging from animals, the report said, citing outbreaks in the past five years, including the Zika virus, Ebola virus and the novel coronavirus (SARS-CoV-2), that causes the COVID-19 disease.

“This is attributed to anthropogenic pressures that we exert on environmental systems, including population growth, rapid urbanisation and climate change,” said Pranav Pandit, veterinary epidemiologist at the University of California, Davis, United States.

Overexploitation of wildlife, resulting from the destruction of their habitats, was also associated with the increased risk of spill over of pathogens, the report said.

Habitat destruction is primarily driven by activities like mining, infrastructure development, including new roads and railways and transformation of natural areas to commercial and retail use.

Such destruction also increases human-wildlife contact and conflict, apart from negatively impacting migration patterns, the report added.

This, in turn, increases the risk of pathogens spilling over to humans.

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