Human invasion of forest land caused bat CoV spread and COVID-19 emergence

The COVID-19 pandemic remains a mystery as scientists try to figure out where the virus came from and how it entered the human host. This line of research is not just academic, as we can determine if, where and why future pandemics caused by unknown agents are likely to occur. After all, this is not the first outbreak of zoonosis in the last few decades, nor the first outbreak caused by pathogenicity Coronavirus Known to infect wildlife species.

Reasons for the emergence of zoonotic diseases

New survey published on Preprint Server medRxiv* In August 2020, we will discuss the underlying causes underlying the outbreak of such infectious diseases following the crossover of strains that separate animal viruses from humans. This first event is very important.

In the current pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) shares 96% genomic sequence identity with the strain found in the bat bat. It is in these animals that most of the early ancestors of SARSr-CoV are found, and they become potential reservoirs for these viruses. However, it is unclear whether this occurred directly, or via an intermediate jump from bats to other species (such as the Malayan ginkgo), or in humans.

Nevertheless, it is clear that increased contact between wild animals and humans facilitates the entry of animal viruses into the animal community. Researchers in the current study point out that this is the effect of several related factors that reduce distance and increase contact rates between humans and wildlife and between humans.

Middle Horseshoe Bat (Rhinolophus affinis). Image credit: Binturong-tonoscarpe / Shutterstock

Factors that promote human-wildlife contact

These factors include the rapid growth of the population, which is constrained in various ways, such as the distribution to less populated spaces and the growth of cities. Increasing per capita income in middle-income countries; and changes in dietary patterns associated with these shifts. In other words, the increased demand for animal products associated with the increased availability of free cash has led to much of the forest land being billed for farmland and livestock, also called forest invasion.

This inevitably affects the ecology of forest systems. Human invasion of areas previously occupied by wildlife, hunting pursuits, and pasture grazing for livestock and pasturing can all contribute to the invasion of human viruses by animal viruses. In addition, the loss of old forests and the division of single forests into smaller, non-viable fragments will extinguish niche animal communities and promote survival of generalist species.

Find Links: Land Use and the Emergence of Pandemics

Therefore, in this study, when there is a link between changes in modern land use and the COVID-19 pandemic, wildland homes include forest fragmentation and human invasion as their main causes. Genus horseshoe bat Linolophos How outbreaks of coronavirus infection occur, given the wide variety of such bats in China and the wide variety of bat coronaviruses (CoVs) that resemble SARS-CoV Used as an index system to indicate.

Researchers have found that two of the four CoV genera, alpha and beta CoV, are found in bats. All four betaCoV subgenera infect bats, including the SARS-related CoV (SARSr-CoV). SARS itself first began in southeastern China and was subsequently tracked. R. sinicus And R. Related, Among other horseshoe bats. As SARSr-CoV mimics the SARS of dangerous humans, we turned to bat habitat disruption in relation to the bat itself. This includes South Asia, East Asia and China.

Univariate spatial analysis of coronavirus outbreak drivers (A) Sampling points randomly generated in China (dark purple) and outside China (light purple) and bat location points (yellow). Asia, weighted by the distribution of bat species of bats present in east, south, and southeast; (B) Livestock density hotspots (red) and coldspots (blue). (C) Forest fragmentation hotspot. (D) Human settlement hotspot.

China crowded with livestock

In China, livestock is abundant in the bat bat area. In fact, it is a more diverse hotspot than any other part of the country, with a higher proportion of domestic poultry, pigs and cattle. The researchers drew a circle with a radius of 30 km from each bat location and found that these livestock were found at a much higher density than in randomly selected areas.

Forest loss and fragmentation

Forest cover and forest fragmentation are statistically more pronounced in areas surrounding random areas of China compared to other areas. This indicates that the forest cover and cultivated land density are low here and the forest is finely divided, unlike other areas surveyed in the same area. This is a randomly chosen location outside of China, but it is more important around the bat’s actual location compared to the bat’s distribution.

Human invasion

Humans also invade horseshoe-shaped bat habitats, build their villages and towns there, and are highly populated. Therefore, these two species share the same hotspot activity. “These results show that China shows stronger signs of deforestation in human invasion, livestock density, and the distribution of SARSr-CoV hosting bats than in other regions,” the researchers say. Areas near forest fragments have low forest and arable land coverage.

In other words, China is one of the key hotspots that integrate all these elements, fragmentation, livestock density, human settlements, some in eastern Nepal, Bangladesh, northeastern India and Kerala. .. Researchers use this knowledge to identify potential spots of future viral spread. This can happen if one or more of these factors cross the boundary of small change and hotspot conditions.

They conclude that the region of China, south of Shanghai, China’s main port, is probably a hotspot due to the rapid fragmentation of forests. Japan and northern Philippines are ready to move for the same reason.

Interacting factors increase epidemic risk

Hotspots in China and less hot spots in Indochina and areas around Thailand’s hotspot show signs of increased human and livestock activity, respectively. In short, these areas are “suitable for the spread of SARSr-CoV from wildlife to humans.” [or] As land use patterns and human invasion increase, there is a “risk of becoming more spilled.”

In addition to ecological impacts and farmland expansion, human and animal movements, trade activities, as well as unique host characteristics and interventions currently adopted (biosecurity, personal protective equipment, meat hygiene), Interact preparation and consumption to reduce the ultimate risk).

Future actions

Researchers have identified threats and potential threats such as maintaining or rebuilding forests, moving livestock pastures and farms far away from forest boundaries, and reducing the density of human activity in these buffer zones. It calls attention to the need to combat these dangerous trends found in hotspots. Future environmental impact assessments should also consider the risk of transforming the affected areas into new hotspots where spilled zoonosis is emerging.

*Important Notices

medRxiv It publishes preliminary, non-peer reviewed scientific reports and should not be considered conclusive and should not guide clinical practice/health-related behaviors or be treated as established information.