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www.thevillagenews.co.za
26 February 2020
MY ENVIRONMENT
Does the coronavirus offer some hope for pangolins? By Dr Anina Lee
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nvironmentalists noticed the irony in the news that the deadly, novel coronavirus pandemic that started in China in December 2019 had been traced to pangolins. After all, until the past few months, the pangolin was the world’s most trafficked and endangered mammal. Pangolins are massively over-harvested for Chinese markets, an over-exploitation which is driving the animals to extinction across the world. Markets, such as the one in Wuhan where the epidemic originated, sell a vast smorgasbord of exotic animals for consumption – from live wolf pups and snakes, to bats and pangolins. Now the pangolin has seemingly struck back. Highly endangered pangolins appear to be vectors for the deadly viral strain. This has unleashed a global health emergency and resulted in a temporary national ban in China on the consumption and trade of wildlife products.
ABOVE: The novel coronavirus pandemic that started in China in December 2019 has been traced to pangolins which, until recently, were the world’s most trafficked and endangered mammal. PHOTO: Getty Images BELOW: A coronavirus looks like a bouncy ball with tiny ‘spikes’ fused across its surface. It was named after these tiny spikes which, at high magnification, resemble a halo or corona. PHOTO: American Society for Microbiology
Many conservationists have expressed the hope that the ban will be permanent. If so, pangolins may still save many of the world’s other endangered vertebrates – tigers, elephants, lions, rhinos, giraffes – and, dare we hope, wildcaught abalone.
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The new virus has had many names in a short time. The latest is COVID-19, not naming the virus, but the disease – Coronavirus Disease-19 (because it appeared in 2019). The DNA of a Coronavirus found in pangolins appears to offer a near-perfect match for the current outbreak of COVID-19, an acute respiratory disease that has killed hundreds. At least 16 of 21 Malayan pangolins handed to a rescue centre by anti-smuggling authorities in March 2019 died. A study revealed that “most of the dead pangolins had a swollen lung which contained a frothy liquid, as well as the symptom of pulmonary fibrosis”. The symptoms are similar to those now displayed by infected humans. Although the carrier species for COVID-19 has not been confirmed, bats are the probable “natural reservoir host”. Scientists have also traced the SARS and Ebola epidemics – both coronavirus members – to bats. So if the new virus originated in bats, how did it manage to jump to humans, and where does the pangolin fit into the story? Coronaviruses are not new. For example, the common flu is caused by a coronavirus. So let’s take a closer look at these viruses.
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cleic Acid) as their genetic material, rather than DNA (Deoxyribonucleic Acid). RNA is a single strand of genetic material, whereas the DNA structure is the classic double-stranded helix. If we look inside a coronavirus we will see that it consists of a capsule and membrane (with spikes growing from its surface) enclosing the coiled RNA. The RNA is a lot bigger than in other RNA viruses. When any organism replicates (multiplies) it has to copy its genetic material. DNA copying is very precise, with many safety mechanisms that prevent it from making mistakes in the copying. Not so RNA copying. It is much more prone to mistakes creeping in. And the longer the RNA strand, the more mistakes can happen. Mistakes represent mutations. Most mutations are harmful to the organism, but a very small number confer an advantage to the virus. Since viruses multiply extremely rapidly, these beneficial mutations can spread relatively quickly. This is why so many new kinds of coronaviruses keep cropping up. It’s also why they are so hard to fight – it’s hard to hit a constantly changing target with vaccines and drugs.
A coronavirus looks like a bouncy ball with tiny ‘spikes’ fused across its surface. At high magnification, these little spikes resemble a halo or corona – hence the name coronavirus. It is the physical structure of these little glycoprotein spikes that determines whether a particular virus is able to attach to and invade a particular host cell.
There is a major difference between coronaviruses that cause a cold and those that cause a severe illness. The common cold virus primarily infects the upper respiratory tract (the nose and throat), whereas the virus that causes COVID-19 thrives in the lower respiratory tract (the lungs) and can lead to pneumonia.
Coronaviruses (like HIV) contain RNA (Ribonu-
That’s not all. Viruses have the ability to mix and
match their RNA. So a mutation or characteristic beneficial to one virus can be transferred to another virus should they end up in the same host. This is what possibly could have happened with COVID-19. The pathogenic bat virus cannot be transferred directly to humans, but it’s a different story if it should end up in the same animal with another virus that can. That animal was probably a pangolin. It’s quite possible that pangolins can ingest bat poo together with the termites on which they feed. One researcher sums it up: “In general, bringing animals together in close proximity increases the chances of viruses crossing between animals and being able to share genetic information, thus creating viruses that can potentially threaten humans. In this case, it appears a pangolin virus and bat virus found themselves in the same animal, which led to a devastating recombination event, creating the pandemic strain. This may have happened in the wild, or where these animals were brought together in unnaturally close proximity.” It is reported that every year, as many as 2.7 million wild pangolins are plucked from central Africa’s forests alone. Pangolin meat is popular as a high-end restaurant delicacy and, in 2019, in just two seizures, Singapore authorities confiscated 26 tons of scales that were destined for use in traditional Chinese medicines. We can but hope that this unfortunate event in human health will at least favour the fortunes of the pangolin.
