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  • By now you've probably heard of COVID-19, or coronavirus disease discovered in 2019,

  • which is responsible for a global pandemic. Thus far the main country affected has been

  • China, but it has spread to a number of other countries around the world to a varying degree.

  • The virus was initially referred to as the 2019-nCoV, or the 2019 novel coronavirus and

  • was informally calledWuhan coronavirus”. The World Health Organization named the disease

  • COVID-19 because it doesn't refer to a geographical location, an animal, a person or group of

  • people - all of which can lead to stigma. They also wanted to make it pronounceable

  • and related to the disease - not an easy task! The virus was officially named SARS CoV-2,

  • or severe acute respiratory syndrome coronavirus 2, because it's genetically very similar

  • to the SARS coronavirus which was responsible forwell the Severe Acute Respiratory Syndrome,

  • or SARS, outbreak in 2002. So SARS-CoV-2 causes COVID-19.

  • Now, coronaviruses that circulate among humans are typically benign, and they cause about

  • a quarter of all common cold illnesses. But occasionally, coronaviruses that circulate

  • in an animal reservoir mutate just enough to where they're able to start infecting

  • and causing disease in humans, if they're given an opportunity. In 2002 SARS was a coronavirus

  • that hopped over from bats to civets, which is a cat-like mammal; and then over to humans.

  • And in 2012, there was MERS, which was a coronavirus that hopped over from bats to camels a few

  • decades ago and then circulated among camels for quite some time before infecting humans.

  • COVID-19 most likely also started with bats, but this time the intermediate host was probably

  • a pangolin, an animal that looks like a cross between an anteater and an armadillo. That's

  • based on the fact that scientists identified a coronavirus in pangolins that's a 96%

  • genetic match to SARS-CoV-2. Sadly, pangolins are heavily trafficked around the planet,

  • largely because people believe that their scales have healing properties. Because they're

  • moved around the world rather than left in the wild, there are ample opportunities for

  • a coronavirus to go from a pangolin to a human.

  • As of February 11, 2020, there have been 43,103 cases of COVID-19 and 1,018 deaths, with a

  • fatality rate of 2.4%, according to WHO. The vast majority of cases and deaths have occurred

  • in China. For a little perspective, the 2002 SARS outbreak resulted in 8,098 cases and 774 deaths,

  • so the fatality rate was around 9.6%. And the 2012 MERS outbreak results in 2,494 cases

  • and 858 deaths, bringing the fatality rate to 34%. Finally, for the 2014 Ebola outbreak,

  • which was not due to a coronavirus, there were 28,639 cases and 11,316 deaths. The fatality

  • rate was a whooping 40%!

  • At a microscopic level, coronaviruses are single strand positive sense RNA viruses with

  • protein spikes on their surface that look a bit like a crown under a microscope. In

  • fact, “coronais latin for crown. Besides looking majestic, these spikes allow the virus

  • to invade cells lining the respiratory tract and lungs. After binding, the coronavirus

  • enters and takes over the cellular machinery to make more and more copies of itself so

  • it can spread to the surrounding cells and get into the mucus.

  • Sometimes the infection is mild, and some people don't develop any symptoms at all.

  • For others, they can develop symptoms that can range from mild symptoms like fever, cough,

  • and shortness of breath, all the way to serious problems like pneumonia. Severe lung damage

  • can cause acute respiratory distress syndrome, or ARDS, which occurs when the lung inflammation

  • is so severe that fluid builds up around and within the lungs. The severe infection can

  • cause septic shock, which happens when the blood pressure falls dramatically and the

  • body's organs are starved for oxygen. ARDS and shock are the main cause of death for

  • people with the infection, and this is more likely to occur in those over the age of 60,

  • smokers, and people with previous medical conditions like hypertension.

  • In addition to causing disease, coronaviruses can spread quickly. Usually the virus spreads

  • when people cough or sneeze, and tiny droplets containing the virus are released. These droplets

  • can land on another person's mouth, nose, or eyes, and that allows the virus to enter

  • a new person. Virus can also be found in a person's stool, and in rare situations coronavirus

  • has been transmitted from one apartment to another within a residential building. This

  • was seen in the 2002 SARS epidemic. At that time, faulty plumbing allowed virus-containing

  • fecal matter originating from one person's apartment to drift from drainage pipes back

  • up into fixtures like sinks and toilets within other apartments in the same building. This

  • created a terrible smell and allowed the virus-containing droplets to deposit on bathroom surfaces,

  • ultimately causing people in those apartments to get ill. Something similar may have happened

  • with COVID-19, and this is being actively investigated.

  • Once a person is infected, symptoms develop an average of 5 days later. This is called

  • the incubation period. However the incubation period varies from person to person, and in

  • some studies, the incubation period lasted as long as 24 days! Now there's debate about

  • whether or not asymptomatic people can spread the disease, because these people typically

  • have low levels of circulating virus. But even if they do, asymptomatic transmission

  • likely plays a minor role in the overall epidemic. Viruses are given a reproductive number or

  • R-naught based on how quickly they spread, and person to person transmission has been

  • confirmed both in and outside of China. An R naught of 1 means that an infected person

  • passes it on to 1 new person, an R-naught of 2 means that 1 person spreads it to 2 new

  • people, and so forth. If the R naught is below 1, the infection peters out, if it's 1 it

  • stays steady, and if it's above 1, then it continues to spread. The current estimate

  • for the SARS-CoV-2 R naught is between 2 and 2.5. Of course that's an average, with some

  • spreading the disease less, and others - called superspreaders - spreading the disease at

  • a much much higher rate. The exact cause of these superspreaders is unclear, perhaps they

  • are just in contact with more folks, perhaps their bodies naturally shed more virus, or

  • perhaps there's some other reason altogether.

  • To confirm the diagnosis, there should be a real time polymerase chain reaction or rt-PCR

  • tests, a quick test used in many labs and hospitals that can detect very small amounts

  • of viral RNA.

  • Treatment is focused on supportive care - providing fluids, oxygen, and ventilatory support for

  • really ill people. There's also some early data showing that three medications are highly

  • effective against SARS-CoV-2 in the laboratory setting. These medications are chloroquine,

  • an anti-malarial drug; ritonavir, an anti-HIV medication; and remdesivir, an antiviral drug

  • previously used against Ebola. Remdesivir was given to the first US patient with COVID-19

  • on day 11 of his illness as he was clinically worsening, and he began to improve the very

  • next day. Large scale clinical trials using remdesivir are already underway in China.

  • Unfortunately there's no vaccine currently available to protect against COVID-19. At

  • best, it looks like a vaccine will be many months away. So the goal is to avoid human

  • to human transmission, starting with isolating people with COVID-19. Coronaviruses don't

  • usually spread over long distances in the air, but they can travel roughly 3 feet or

  • 1 meter from one person to another on tiny droplets of saliva, which are produced when

  • someone's coughing or sneezing. In addition, some strains of coronavirus can survive on

  • surfaces for over a day. With that in mind, if you're a healthy person living in a non-outbreak

  • area, the recommendation is to avoid travel to disease outbreak areas, generally stay

  • away from crowded places, and stay at least 6 feet or 2 meters away from anyone with symptoms.

  • Wearing a surgical mask is not recommended because the general risk of getting COVID-19

  • in these settings is so low. As always, careful hand washing is key and it should be done

  • with soap or alcohol-based hand sanitizers and scrubbing. Also, avoid touching your eyes,

  • nose, and mouththis is the area, known as your T-zone is a common entry point for

  • viruses into the body.

  • For healthcare workers who are around people with COVID-19, the recommendation is to apply

  • droplet and contact precautions. That includes wearing personal protective equipment like

  • a clean, dry surgical mask, gloves, long-sleeved gowns, and eye protection like goggles or

  • a face shield. When performing a procedure that generates aerosol, like tracheal intubation,

  • bronchoscopy, CPR, or noninvasive ventilation, it's important to wear a N95 respirator.

  • This prevents 95% of the small particles, like respiratory droplets, from passing through.

  • To recap, the SARS-CoV-2 virus causes a respiratory disease called COVID-19. The virus probably

  • originated from bats, then went to pangolins as an intermediate host, and finally to humans.

  • The virus travels in respiratory droplets and enters the body via the mouth, nose, or

  • eyes. Once inside the body, it replicates in the respiratory system, causing symptoms

  • like fever, cough, and shortness of breath. Some people might develop more dangerous complications

  • like pneumonia, ARDS, and shock. Treatments are focused on supportive care, but certain

  • medications like Remdesivir are currently in clinical trials. In the meantime, the best

  • strategy is prevention -- this includes careful hand washing, avoiding traveling to disease

  • outbreak areas and crowded places when possible, avoiding touching your T-zone, and if you're

  • a healthcare worker to use personal protective equipment.

By now you've probably heard of COVID-19, or coronavirus disease discovered in 2019,

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B2 US de la una los covid sars

COVID-19 (Coronavirus Disease 19) - causes, symptoms, diagnosis, treatment, pathology

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    Tina Huang posted on 2020/02/25
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