Why pathogens travel in search of a host-THE HINDU-26-04-2020
Claims were made of the virus being manufactured in laboratories and then shipped to nations to let loose on their populations. In a paper published on March 17, Nature Medicine busted the theory of a lab-cultured SARS-CoV-2. The paper, The proximal origin of SARS-CoV-2, by Kristian G. Ian Lipkin et al, made it clear that this was a case of zoonoses. The “analyses clearly show that SARS-CoV-2 is not a laboratory construct or a purposefully manipulated virus”.
What are zoonoses?
The first possible source heard of in relation to the COVID-19 epidemic was the wet market in Huanan, Wuhan, China. While subsequent studies cast doubts on the link, it is quite possible that an animal source was present at this location, the Nature paper argues.
The issue of pathogens crossing species to cause diseases is not a new concept. According to the United Nations Environment Programme , 60% of all infectious diseases in humans are zoonotic, and about 75% of all emerging infectious diseases are zoonotic in nature.
Why are zoonotic diseases prevalent?
The inevitable interaction between humans and livestock with wildlife exposes the human species to the risk of spillover of potential pathogens. For many zoonotic diseases or zoonoses, livestock serve as an epidemiological bridge between wildlife and human infections. A presentation by the UNEP argues, “Ecosystem integrity underlines human health and development. Human-induced environmental changes modify wildlife population structure and reduce biodiversity, resulting in new environmental conditions that favour particular hosts, vectors, and/or pathogens.
” Consequently, preserving ecosystem integrity can actually help regulate diseases by supporting a diversity of species so that it is more difficult for one pathogen to spill over, amplify or dominate. Our continued erosion of wild spaces has brought us uncomfortably close to animals and plants that harbour diseases that can jump to humans. Changes in weather patterns, and extreme weather events affect the distribution areas of disease, pathogens and pests. Also, changes in human behaviour, including travel, conflicts, migration, wildlife trade, urbanisation, and dietary and medical preferences, can result in disease emergence, according to researchers at the UNEP.
What lies ahead?
Growing evidence suggests that outbreaks or epidemic diseases may become more frequent as changes continue to have an impact on the ecosystem. But doing nothing will only let these pathogens flourish, jump hosts and make a terrible assault on humans.