Scientists mostly agree that many of the earliest known infections and deaths were centered around a wildlife market in Wuhan, China.
But researchers have been unable, in the three years since Covid-19 emerged, to determine how the first victim became infected with it, sparking a pandemic that has since killed nearly seven million people, according to an official tally by the World Health Organization, and much more if the number includes deaths from the corona virus.
DNA
Controversy intensified recently after a Chinese research team added DNA evidence taken off the market during the pandemic to an international gene sequence database. Previously undisclosed data indicated the presence of wild animals in the same section of the market where the team found SARS-CoV-2. Raccoon dogs, bamboo rats and porcupines were among the animals known to be susceptible to bat viruses. Some scientists have said, although not conclusively, that the data adds evidence to the theory that the virus jumped from animals to humans through what is called “zoonosis” and is the source of many infectious diseases in humans. Other scientists suspect the pathogen may have somehow leaked from a lab in Wuhan, 27 kilometers from the market, where researchers study bat viruses. The idea gained traction earlier this year when the US Department of Energy said, with “low confidence” in a report, that the outbreak was likely the result of a virus leak from a lab. Other US agencies that have studied the matter tend to have natural proliferation processes, although they are also inconclusive. The exact basis of the ratings has not been made public.
Ambiguity reigns supreme
Although how the virus arrived in Wuhan remains a mystery, the risks of spread are increasing significantly in China, including in several areas within 400 kilometers of the market. Chinese court records are full of cases of wild animals being hunted in dangerous areas, and scientists from the Wuhan lab have taken samples of bats there. An analysis of Reuters data showed that human encroachment on bat habitats in recent decades has turned parts of China into an epidemic minefield. These areas, which news agencies call “jump zones,” combine factors such as tree loss, rainfall and the presence of bat species to create conditions in which infection is the more likely to spread.
jump zones
Data shows that between 2002 and 2019, China’s “jump zones” expanded by 54 percent, an increase of 150,000 square kilometers, an area larger than that of Nepal. One such jump zone includes mountains and lakes, 175 kilometers southeast of the Wuhan market. The area around China’s giant Poyang Lake has been severely degraded by dam construction, mining and pig farming. Scientists continue to search for definitive evidence on the geographic or biological origins of COVID-19. The mystery persists, in part, because Beijing has not authorized an independent investigation into either an infected animal or the virus escaping from a lab. Origin of COVID-19 The Chinese government says it supports and participates in research to determine the origin of COVID-19. The United States is accused of politicizing the case, in particular because of the efforts of American intelligence agencies to investigate. Chinese Foreign Ministry spokeswoman Mao Ning said at a press conference last March: “Assigning responsibility for a scientific matter to the intelligence community is a clear sign that the matter has been politicized. Early in the outbreak, Chinese scientists found the causative agent of COVID-19 on surfaces of bathrooms and drains in the Wuhan market, where wild animals were sold. But there is no evidence yet that they tested live animals before the government closed the market. With no further evidence, theories began circulating about the virus leaking from a lab.
The story of the emergence of the virus in China
Both possibilities have a history in China. In late 2002, SARS-CoV-1 emerged in Guangdong, southern China, and the SARS epidemic broke out in 2003. At that time, scientists tested animals in the local market and found the virus in a palm civet, as well as evidence of infection in a raccoon dog and a mongoose badger. Scientists have largely identified animal-to-human transmission as the source of the pandemic. After the SARS pandemic ended, two graduate students were infected with SARS while working at the National Institute of Virology in Beijing, where scientists were studying the pathogen. This epidemic, although contained, infected nine people and killed one. This incident has become a benchmark for those who suspect that a leak from a laboratory is responsible for the Covid-19 epidemic. In 2010, Zhong Nanshan, a doctor who led China’s program to fight SARS and in the years following COVID-19, told a Chinese newspaper that “the ecological balance between man and nature is overexploited”. He pointed to the discovery of SARS-like viruses in Wuhan and Hong Kong in horseshoe bats. A research paper cited his comments. Reuters quoted Nanshan as saying: “If we take strict measures, I believe SARS will not come back. If we do not strengthen our measures, he will certainly come back.
match
Since the emergence of SARS-CoV-2, scientists have found close matches to the virus in samples taken from bats in Yunnan. Researchers have also found viruses closely linked to the cause of COVID-19 in bats across the border in Laos. But none of them were close enough to the SARS-CoV-2 virus to be its direct ancestor. Finding an exact match can be like finding a needle in a haystack, as the saying goes. Without conclusive evidence, predictions are likely to persist. Western governments and much of the global scientific community have urged China to be more open and cooperative with its researchers’ findings. “We continue to call on China to be transparent in sharing data, conducting necessary investigations and sharing results,” WHO Director-General Tedros Adhanom Ghebreyesus said during a briefing. press in March. “Understanding how the pandemic began remains a moral and scientific imperative.”
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