- Numerous studies indicate that COVID-19 is a
zoonotic disease,transferred from animals to humans.
- A recent article supports the argument that the pandemic is more likely to have started in a market than in a laboratory.
- Interestingly, the authors also discuss whether African swine fever could have played a role in the spillover event that led to the COVID-19 pandemic.
Researchers at the University of Glasgow in the UK recently took a fresh look at how the COVID-19 pandemic emerged in China.
Their results confirm previous work indicating an “intermediate animal host” that may have introduced SARS-CoV-2 into humans.
The article also discusses the possibility that an African swine fever outbreak helped create a situation that gave pathogens more opportunities to move from animals to humans.
The current article begins in 2002, discussing the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), which appeared in Foshan, Guangdong Province, China, and has spread to 29 other countries.
More than 8,000 people contracted SARS-CoV before public health measures halted its progression in 2003.
Experts have linked the origin of the virus to live market animals.
In 2005, researchers found that horseshoe bats in China harbored SARS-linked coronaviruses (SARSr-CoV).
They speculated that “a [SARSr-CoV] circulating in horseshoe bats seeded the SARS-CoV progenitor in an animal intermediate host.
Scientists have examined badgers, civets and raccoon dogs as possible carriers of the virus. They identified civets as the most likely emitters.
Virologists have speculated that a civet cat could have been exposed to SARSr-CoV before being captured. An alternative theory suggests that a captive civet may have contracted the virus from bats that feed in markets.
In 2019, SARS-CoV-2, the virus that causes COVID-19, emerged in the city of Wuhan, China. Some have implicated the Wuhan Institute of Virology as the source of the pandemic.
Wuhan is more than 1,500 kilometers from Yunnan province, the closest known site to naturally occurring SARSr-CoV collected from horseshoe bats.
In addition, these viruses collected in Yunnan were “very different from the progenitor of SARS-CoV-2”.
In their article, the authors question the focus on bat colonies in Yunnan. They explain that the geographic range of horseshoe bats is wide – from east to west China and beyond. They also explain that additional sampling has identified other coronaviruses genetically close to SARS-CoV-2 circulating in horseshoe bats.
The first cases of SARS-CoV-2 detected at the end of 2019 were linked to
The months of November and December 2019 also saw “multiple spillover events associated with the animal market”. The newspaper explains that “[t]The emergence of SARS-CoV-2 has properties that correspond to a natural overflow.
Among several live animal species sold in Wuhan markets, raccoon dogs, civets, foxes and mink are susceptible to viruses linked to SARS.
Lytras and his colleagues conclude that the COVID-19 pandemic stems from human contact with live animals carrying the virus.
The document also speculates that changes in China’s meat supply may have played a role in the spread of SARS-CoV-2.
African swine fever is a haemorrhagic fever often fatal in pigs but harmless to humans. In 2018, a major epidemic African swine fever has led to the slaughter of 150 million pigs. This resulted in a shortage of pork products and a surge in prices the following year.
Although the production and sale of meat from other livestock, such as cows and chickens, has increased, this has not been enough to make up for the pork shortage.
The authors of the new article hypothesize that as a result, “consumers and food producers may have resorted to alternative meats, including wild farmed or captured animals, particularly in the southern part of the country. China where wildlife is traditionally eaten “.
This prospect states: “The resulting increase in the trade in farm animals and wildlife may have brought humans into more frequent contact with meat products and animals infected with zoonotic pathogens, including SARSr-CoV. ”
At the same time, in an effort to reduce the transport of live pigs, the Chinese government introduced financial incentives to transport frozen pork. According to the authors of the article, this may have encouraged the transport of other species susceptible to infection with SARSr-CoV.
The exact animal source of SARS-CoV-2, however, is still unknown.
Dr Jonathan Stoye is a renowned virologist and senior group leader at the Francis Crick Institute in the UK In an interview with Medical News Today, Dr Stoye observed that this article provides “an excellent summary of the features supporting the case that the introduction of [COVID-19] to humans involved an intermediate host.
The virologist, who was not involved in this article, noted that the authors’ conclusion was similar to the
Dr Stoye warned that this prospect “does not prove a transfer from bats to humans”.
He was, however, intrigued by the author’s theory that a pig shortage could have provided fertile ground for an overflow event; this possibility has not received much attention.
Scientists expect to see new Variants of SARS-CoV emerge. Researchers at the University of Glasgow say the discovery of these variants and other viruses linked to SARS underscores the importance of “monitoring the diversity of coronaviruses.”
In March 2020, the World Health Organization (WHO) issued recommendations to reduce animal-to-human transmission of SARS-CoV-2 in live markets.
These guidelines include general hygiene practices and avoid the consumption of raw or undercooked animal products from these markets.
WHO is also asking veterinarians to report unusual incidents involving market animals.
The authors fear that now humans are “the dominant host species of SARS-CoV-2”, we could transmit coronaviruses to animals. This process of reverse zoonosis seems to have taken place between Virginia deer in the USA.
However, in his interview, Dr Stoye predicted a “gradual decrease” in the spread of SARS-CoV-2. This seems to happen in areas with higher vaccinations.
For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.