All about respiratory coronavirus infections

All about respiratory coronavirus infections

Covid-19 disease, which appeared in China in late 2019, is caused by SARS-CoV-2, a virus that belongs to a large family, the coronaviruses. Very common, they can cause a simple cold as well as a serious respiratory infection such as pneumonia, causing fatal epidemics as was the case with Sras or Mers and now with Covid-19. Symptoms, transmission, number of cases, preventive measures. We take stock.

What is a coronavirus?

How are emerging coronaviruses transmitted?
What are the symptoms of Covid-19?
Is there a vaccine for Covid-19?
Are there people at risk of developing a more severe form of the disease?
How to treat an infection with the new coronavirus?
How many people are affected by Covid-19?
What measures are in place at stage 3 of the epidemic?
What is the procedure for taking care of patients in France?
What is a coronavirus?
Coronaviruses, which owe their name to the crown shape of the proteins that coat them, are part of a large family of viruses, some of which infect different animals, others humans. They are likely to cause a wide range of diseases. In humans, these diseases range from the common cold to a severe lung infection, responsible for acute respiratory distress.

Coronaviruses cause deadly epidemics
On the subject, Inserm recalls that two deadly epidemics have already occurred in the 21st century, involving emerging coronaviruses, hosted by animals and suddenly transmitted to humans:

SARS-CoV (2002-2003), or coronavirus causing severe acute respiratory syndrome (SARS), which appeared in China: more than 8,000 cases were identified in 30 countries and 774 people died (almost 10% mortality).
MERS-CoV (2012-2013), or Middle East respiratory syndrome coronavirus, so called because it was first detected in Saudi Arabia. 1,589 cases and 567 deaths in 26 countries have been recorded (a death rate of around 30%).
The third fatal epidemic is that related to SARS-CoV-2, which appeared in China in December 2019. The first cases identified are people who went to a local market, in Wuhan, in Hubei province. Virologically, SARS-CoV-2 is very close to SARS-CoV, which is why it was placed in the same species of coronavirus (followed by the number 2 to distinguish it from the previous one).

How are emerging coronaviruses transmitted?
Coronaviruses are of animal origin: one species ("reservoir") harbors a virus without being sick and transmits it to another species, which then transmits it to humans. In the cases of SARS-CoV and MERS-CoV, the reservoir animal was the bat. As Inserm explains, "the virus is asymptomatic in this animal. An intermediate host is therefore necessary for the transmission of these viruses to humans: the masked palm civet for SARS-CoV, sold on the markets and consumed in southern China, and the dromedary for MERS-CoV. "

With regard to SARS-CoV-2, the reservoir could also be the bat. In early February, a team of Chinese researchers from the South China Agricultural University estimated that the missing link could be the endangered pangolin, a small scale mammal. But caution is advised, pending a final confirmation. The virus is said to pass into humans via animal secretions, under specific conditions that have yet to be identified.

Human-to-human transmission

The SARS-CoV, SARS-CoV-2, and MERS-CoV coronaviruses are not only transmitted from animals to humans but also from humans to humans. Concerning Covid-19 disease (formerly known as 2019-nCoV) due to SARS-CoV-2, it is transmitted by postillions (saliva droplets) projected by coughing or sneezing. Close and prolonged contact is therefore necessary to transmit it (family, same hospital or boarding room) or to have had contact within 1 meter of the patient, in the absence of effective protective measures.

Read also :
Kissing, shaking hands, touching your face ... how to change our bad habits when faced with coronavirus?
Environmental transmission
One of the most important transmission factors seems to be hand contact with infected surfaces and then with the mouth, nose or eyes. Depending on temperatures and humidity, the virus can survive for a few hours or even a few days on various surfaces if they are not disinfected. Studies are underway to clarify these data.


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