COVID-19: Need to relook human relationship with wild, domestic animals, says report

The spread of the novel coronavirus disease (COVID-19) has triggered the need to understand zoonotic diseases more than before. A new study has shed light on the need for coordination efforts among experts to find out how diseases related to wild, feral and domestic animals — that have the potential to be the source of future epidemics — can be prevented.

The interventions could range from medical and veterinary to simple behavioural and societal; but these could greatly reduce the risk of pathogen transfer, according to the study published in Biological Reviews July 7, 2021. 

Researchers from University of Cambridge identified and collated 161 options that could significantly reduce the chances of disease transmission from animals to humans.

All categories of animals — wildlife, captive and domestic livestock — were included in the study. The researchers focussed on pathogens, especially the viruses that can be transmitted from animals to humans and had the chance of acquiring epidemic potential.

The study looked at the risks posed by different transmission pathways for zoonotic disease spillover and used solution scanning (listing of all known options to come to a solution) to reduce these risks.

The origin of SARS-CoV-2, the causative virus of COVID-19, was possibly the result of zoonotic transmission from an animal host to humans.

A detailed understanding of how an animal virus jumped species boundaries to infect humans so productively would help in the prevention of future zoonotic events. If SARS-CoV-2 pre-adapted in another animal species, then there is the risk of future re-emergence events.

The study looked at disease transfer to humans involving wild animals, domestic animals and wild or exotic pets.

Most emerging infectious diseases originated from wild animals like non-human primates, rodents and bats and the diseases were transmitted to humans through an intermediate animal host (companion, farmed or feral animals).

Ebola has been suggested to have been transmitted from bats, either directly or via an intermediate host, while Middle-East Respiratory Syndrome likely originated in a species of bat, with the dromedary camel Camelus dromedarius as an intermediate host.

Destruction of biodiversity and increased human interaction with wild animals and wild animal products can increase the chance of zoonotic disease emergence.

To curtail zoonotic emergence from animals to humans, the study looked at four options:

• Supply side measures (production / sourcing of animals)
• Transport and sale (transactional interventions involving and regulation and legislative control)
• Measures to tackle consumption (demand side interventions to reduce the frequency of a high risk product being used or shift demand away from high risk products towards lower risk ones)
• Measures to create appropriate enabling environments (create markets for sustainable and low risk products and certification)

The call for a complete ban on hunting, wildlife trade and wet markets skip the importance that wildlife contributes to global diets, to fisheries and sustainable products. Wet markets are an important and affordable source of fresh produce for many.

The solution could include stronger enforcement on illegal wildlife trade and ban on high-risk wildlife trade to tackle emerging zoonotic diseases with epidemic potential into humans.

Research investigating public health and domestic animal health threats from wildlife must work in tandem with the biodiversity crisis to improve our understanding of the drivers of environmental change and how these lead to emergence of diseases.