By CAPosts 21 November, 2020 - 05:30pm 28 views
About a year has passed since the first cases of covid 19 were detected in Wuhan, but its origin is still unknown. Was a pangolin the animal that transmitted the SARS-Cov2 coronavirus to us? Did the pathogen jump to humans in China or, as your government points out, was it able to do so in another country? The World Health Organization (WHO) has begun the first steps of an investigation to find answers, keys to understanding the virus and avoiding future pandemics. But the unknowns are multiplying.
The "zero patient" has never been identified, the first infected human from whom the world-changing pandemic began. The origin of the virus is only known with certainty that its closest relatives were found in bats in the southwest Chinese province of Yunnan in 2013 and 2019. But the first cases were detected more than a thousand kilometers, in Wuhan , in around the first days of December, perhaps a little earlier.
It is quite possible that "the virus was already circulating before humans realized it was there," experts such as the American virologist Ian Lipkin, who advises the Chinese government and participated in the investigation to find the origin of MERS in 2015.
“The history of the origin is missing many key details”, from the history of its evolution or its ancestors, to the “place, time and mechanism of transmission of the first human infection ”, has written the microbiologist David Relman in the journal PNAS .
This is exactly what the mission of the WHO wants to determine. But his research begins at a point of departure highly politicized by the disputes between China and the United States, in which opacity predominates, much information is lacking, and that void has been filled, in many cases, with hypotheses of all kinds, including the possibility - discounted by many scientists - that the virus was created and escaped from a laboratory.
The research team held its first preliminary meeting by videoconference on October 30 . After months of negotiations with the Chinese government, the WHO has just published very discreetly its plan for the development of the investigation. The United States, which during the Trump administration has attributed the WHO to being too close to China's interests, has accused the mission of a lack of transparency and of being "inconsistent with the mandate given by the member states."
The mission It will have two phases and will be carried out by ten Chinese and ten international experts (epidemiologists, virologists, public health experts, zoologists and food health permits from Russia, Australia, Sudan, Denmark, Holland, Germany, Japan, Vietnam, United Kingdom The first phase will start in Wuhan, before expanding to the rest of China and other countries. Initially, only Chinese scientists will participate in the field work; international experts will provide remote support and travel to the original focus of the pandemic after they have analyzed the results of those initial work. Longer-term studies will be addressed in the second phase.
"Preventing the next pandemic depends on our understanding the origins of it"
In Wuhan, one of the branches of the investigation will take experts to the Huanan seafood market, where it was initially believed that the disease could have originated. Today covered by fences, these facilities, divided into two wings along a wide avenue, housed 653 stalls that sold vegetables, fish and all kinds of domestic and wild animals, living and dead. From quail to sika deer, from giant salamanders to squirrels, raccoons and civets. A study among 41 of the first cases found that about thirty had contact with the market; the rest, no, including three of the first four cases.
But in the first days, when it was suspected that it was the origin of the disease, it was abruptly closed and the animals were sacrificed, without taking samples. They did take samples of frozen pieces, as well as environmental samples collected from the ground, door knobs or drains. According to the plan ( Terms of Reference , or TOR ) of the WHO, a total of 1,200 specimens were obtained. None of the 336 samples obtained from the animals showed traces of SARS-Cov2. On the other hand, 8% of the environmental samples, especially those taken from pipes and drains, did test positive.
"It remains unclear whether the market was a source of contamination, acted as an amplifier for human-to-human transmission, or was a combination of these factors," the WHO report notes. The document also alludes to a study last spring that found that 14% of Wuhan cats, domestic or wild, tested positive for the virus. "Preliminary studies have not generated credible indications that allow reducing the area of investigation," explains the document.
The members of the mission, among other things, will examine the medical records of patients in Wuhan hospitals, to determine if the virus was already circulating before December 2019. They will interview the first cases, to determine how they could be infected. Above all, they will examine blood samples taken before and after the outbreak was detected, and stored in hospitals, for possible antibodies. If found, researchers will have to trace the activities of the carriers, to determine how they were infected. If it could be due to a displacement to a certain place, or because of their work.
“In the case of SARS -the coronavirus related to SARS-Cov2 that killed more than 800 people in 2002-2003- and MERS, the key was to use antibody tests ”to identify the origin, Lipkin pointed out in a talk with foreign correspondents in Beijing.
The experts will also take and examine blood, urine and feces samples from animals found in markets or farms, with which trade or that may have contact with humans, in search of signs of the virus, and will carry out genetic studies. They will also examine the samples taken in Huanan, to try to determine where and how these animals got there.
A study had pointed out that the animal that served as an intermediate vector to pass the pathogen from bats to humans could be the pangolin , although it has never been proven for sure; Experts such as Wang Linfa, from the Duke-NSU School of Medicine in Singapore and who participated in the search for the origins of SARS, do not rule out that the original contagion could occur in a neighboring country, habitat such as southwest China of bats from horseshoe that are considered the greatest carriers of coronavirus. The recent outbreak among minks in Denmark has added one more element to the puzzle.
From the initial result, broader long-term plans will be developed, which may extend outside of China, perhaps to the bat population in neighboring countries. The TOR specifically mentions cases of virus DNA detected in pipes months before the outbreak in Wuhan, a possible allusion to the Barcelona study.
The WHO has stated that the mission will be “open-minded, meticulous, without excluding any hypothesis that can contribute to generate evidence and focus the focus of the investigation ”. The stakes are high. “Preventing the next pandemic depends on our understanding the origins of it,” wrote the microbiologist Relman.