Cough, fever, muscle pain, respiratory distress … Covid-19 disease is causing more and more people worldwide. Evolution of symptoms, signs of severity, transmission, contagion, treatments … Identity card of a worrying disease.
At the end of 2019, grouped cases of pneumonia occurred in China, some of them fatal. January 9, the virus responsible is identified, it is a new coronavirus. It is very contagious. In March, this virus spread over 5 continents and affected more than 150 countries, near 190,000 people and do more than 7000 dead. What do we know about him?
After being baptized nCoV-2019 at first, this new coronavirus was called SARS-CoV-2 (SARS for “Severe Acute Respiratory Syndrome” and CoV for “COronaVirus”). His illness was named Covid-19 February 11, 2020 to be “easier to pronounce” had justified the director general of WHO Tedros Adhanom Ghebreyesus.
Meaning : “Co” means “corona”, “vi” for “virus” and that “D” for “disease”. The number 19 indicates the year of its appearance: 2019. “We had to find a name that did not refer to a geographic location, an animal, an individual or a group of people” added the general manager, to avoid any stigmatization of the disease.
SARS-CoV-2 belongs to the family of coronavirus (with a large number of viruses) which can cause mild illnesses in humans such as colds and more serious pathologies as the Sras. The contamination isanimal origin. The epidemic is part of a Wuhan local market in China where were sold animals wild. Currently, it is still unclear which animal is responsible for it. It could be the bat where a virus very similar to Sars-CoV-2 was detected. On February 7, 2020, scientists from the Southern China University of Agriculture identified the pangolin as a “possible intermediate host” suspected of having transmitted the coronavirus to humans. This small mammal consumed in southern China could be implicated as intermediate host between the bat and humans. The pangolin is a mammal covered with scales threatened with extinction, whose delicate flesh is highly prized in Chinese and Vietnamese gastronomy. In a press release, scientists explain that an animal can carry a virus without being sick and transmit it to other species such as humans. After analyzing 1,000 samples, scientists were able to show that the genomes of virus sequences taken from pangolins were 99% identical to viruses found in people with nCoV, says Chine Nouvelle. Recall that during the 2002-2003 SARS epidemic, the intermediate host of the virus was the civet, a small animal with a gray coat whose meat is eaten in China. The bat was also responsible for the transmission of viruses to humans, including SARS, MERS in Saudi Arabia, and also Ebola.
According to the latest scientific data, there are indeed two circulating strains of the virus (L and S).
- The S strain is said to be older than the L strain. At this stage, there is nothing to confirm whether the mutation took place in humans or in intermediate hosts (animals).
- The L strain would be the most severe and frequent circulating strain (70% of the samples tested in the study), while the S strain would be less aggressive and less frequent (30% of the samples).
“Thanks to the means of detection and the measures to combat the coronavirus, the circulation of the L strain, more severe and therefore more easily detectable, tends to decrease” indicates the government on its site.
The peculiarity of the new coronavirus, in comparison to Sras or the Mers virus, is its contagion. “The SARS coronavirus was contagious only a few days after the onset of symptoms, 4 days later. This left time to diagnose and isolate the patients before they contaminated other people. With SARS, all the patients had severe forms so they were all identified, we did not miss benign forms which could have been unnoticed. With this coronavirus, contagion begins with the onset of symptoms and sometimes in people who do not have symptoms” explained Professor Arnaud Fontanet, epidemiologist at the Institut Pasteur during a round table in the Senate on February 26, 2020.
→ A more contagious virus than the flu: the transmissibility of SARS-CoV-2 is higher than that of seasonal influenza and MERS-CoV, and comparable to that of SARS-CoV.
The average incubation time is 4 days with a maximum duration of 12 to 14 days.
The WHO distinguishes several clinical syndromes associated with SARS-CoV-2: uncomplicated disease, non-severe pneumonia, severe pneumonia, ARDS (acute respiratory distress syndrome), sepsis and septic shock.
Unlike the flu that comes on suddenly, a coronavirus infection “is done gradually over several days” says the Pasteur Institute.
→ First symptoms : headache, body aches, muscle pain, fatigue.
→ Then come fever, cough.
→ then respiratory signs after a week when the infection gets worse: difficulty breathing … which can lead to acute respiratory distress syndrome that is to say a failure of the respiratory functions.
To note : Unlike the SARS coronavirus, the forms of which were still severe, the coronavirus linked to the Covid-19 epidemic is associated with asymptomatic and benign forms with a more serious development after a week.
Signs of gravity
In severe forms of pneumonia caused by the coronavirus, the following symptoms are observed:
- fever and reduced respiratory rate
- severe acute respiratory distress
In children: cough or shortness of breath associated with any of the following signs: cyanosis, acute respiratory distress (whining), signs of pneumonia with an alarm sign: unable to drink or breastfeed, loss of consciousness or seizures.
Coronavirus in children
Children and adolescents are much less often suffering from symptomatic forms: those under 10 years old represent 1% of cases, those between 10 and 19 years old 1% of the 72,314 Chinese cases described by Wu in a study published in the Jama February 24, 2020. This peculiarity is shared with MERS-CoV infection and influenza.
Coronavirus in pregnant women
Two publications on Covid-19 relate to pregnant women. The one published in the Lancet concerns 9 women, aged 26 to 40, with documented SARS-CoV-2 infection in the third trimester of pregnancy and no comorbidity. It did not show any particular gravity of the infection at the end of pregnancy and of a transmission to the fetus. The other also concerns 9 pregnant women (including 1 twin pregnancy) and reports the absence of difference in the clinical presentation of the infection.
Like all coronaviruses, the new coronavirus is transmits between humans through saliva, droplets (cough, sneezing), through close contact with patients (handshakes …) and by contact with contaminated surfaces (coronaviruses survive up to 3 hours on dry inert surfaces and up to 6 days in a humid environment). Regular hand washing (approximately every hour) and wearing masks help reduce the spread of the virus.
Transmission via stool
As indicated by the High Council of Public Health in an Opinion delivered on March 5 “SARS-CoV-2 can be found in body fluids including stool. However, the infectious nature of the virus detected in the stool in some cases is not proven and the risk of faecal transmission has not been documented” .
Animal transmission
There is currently no evidence that domestic animals such as dogs and cats can spread the virus and / or be infected by humans.
Water transmission : To date, no water contamination has been reported. “This disease is respiratory and probably animal to human, but the source has not yet been identified” explains the French government.
A diagnostic test developed by the national reference center for respiratory viruses (Institut Pasteur) is available in France to diagnose infection with this new coronavirus. It is currently performed by a specific laboratory technique on a nasopharyngeal swab whose results can usually be obtained in 4 hours. No commercial test is available. There is :
- systematic sampling of the upper respiratory tract (nasopharyngeal / Virocult® swabs or aspirations)
- a sample of the lower respiratory tract (sputum, LBA, ATB) in case of parenchymal involvement.
No treatment has proven its total effectiveness in combating SARS-CoV-2. Numerous clinical trials testing the efficacy of drugs against the coronavirus are in progress and listed by the WHO.
- In mild forms of the disease that do not require hospitalization: in case of fever, it is advisable to take paracetamol rather than anti-inflammatory drugs which can make the infection flare up. Watch for symptoms and if it gets worse with difficulty breathing, call 15.
- To the hospital, For the treatment of patients with more serious forms, two drugs are used: “It’s about Remdesivir which had been developed for the Ebola hemorrhagic fever (and is reserved for severe forms in Covid-19 patients) and an even older drug, Ritonavir which is a anti HIV medication” indicated Catherine Leport, infectious disease specialist and member of the Coreb mission, on February 26 in the Senate.
Chloroquine tested
The chloroquine is an antimalarial in the testing phase in Marseille to treathe patients with Covid-19. They are “promising” and “will be expanded,” government spokeswoman Sibeth Ndiaye said on Tuesday (March 17th). In China, around twenty clinical trials are underway to analyze the effectiveness of this molecule in patients infected with SARS-CoV-2. Hydroxycholoroquine (a chloroquine analogue) used to treat rheumatoid arthritis and lupus is also the subject of two trials in China in COVID-19 disease.
In addition, antibiotic therapy is used in the event of pneumonia.
With the coronavirus epidemic just beginning in France, researchers are busy developing a vaccine against this highly contagious virus. On RTL, a researcher from the Institut Pasteur indicated that tests on mice would start on Wednesday March 11: “The tests will last a month, a month and a half: we vaccinate mice, then we regularly take their blood to see if they have made antibodies against the vaccine. If they have made antibodies, we infect them with the coronavirus and we see if they resist.” The researchers hope to quickly put in place a vaccine.
Covid-19 has high mortality in adults.
80% of those who die are over 60. For children, these are mild clinical forms. The death rate is estimated at around 2%, more than the flu therefore.
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