Coronavirus infection

What is coronavirus infection?

We will analyze the causes of occurrence, diagnosis and treatment methods. (Coronavirus infection)

Definition of disease. Causes of the disease

Coronavirus infection is a group of acute infectious diseases caused by different serotypes of coronaviruses. It is characterized by a syndrome of general infectious intoxication and a syndrome of lesions of the respiratory tract, mainly of the upper and middle parts of it – the nose, pharynx, larynx, trachea and bronchi. In some variants of the virus, severe acute respiratory syndrome with high mortality develops in 20% of cases.

Etiology

Strains pathogenic to humans belong to the genus Beta coronavirus. They can be divided into two groups:

Strains that lead to diseases like mild ARVI year-round: HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1. They differ at the genetic level in terms of genome size and antigen properties. These types of coronavirus cause malaise, a runny nose, a sore throat, a slight fever, and a rare cough.

Strains leading to severe lower respiratory tract infections:

MERS- COVID (natural source of the virus – one-humped camels);

SARS- COVID (natural source of the virus – bats; intermediate carrier of the virus – camels, Himalayan civets);

SARS- COVID 2 is a new type of coronavirus that caused a pandemic in 2019-2020. (Natural source unknown).

Coronaviruses are helically symmetric RNA viruses with one RNA strand. They are spherical formations 80-220 nm in size. Outwardly, they resemble the solar corona due to their super capsid-lipid envelope surrounded by protein spikes. This is where the name of these viruses comes from.

The “corona” of the virus (left) and the corona of the sun (right)

Coronaviruses produce a number of enzymes (protease, helicase, repli case) and non-structural proteins that break down protein bonds in human cells. They also suppress the production of interferon, which helps fight viruses, provoke inflammation and trigger apoptosis – programmed cell death.

Coronavirus infection has a rather sophisticated method of penetrating the cells of the body. Surface protein “spines” on the border of the viral particle mimic substances useful for the cell. They are mistakenly recognized by the Trans membrane receptors of the cell and given “permission” to enter. At the same time, the immune system does not react to the penetration of the virus, since it sees no reason to attack material that is not dangerous for the body.

The structure of the virus

SARS-CoV-2 in this regard has more favorable conditions for entering the cell. Although it is more contagious, it often does not lead to a catastrophe at the level of cells and organs – a severe course, as a rule, is associated with an exacerbation and worsening of existing chronic diseases against the background of the disease.

After attaching to the cell, the virus “pushes” the cell membrane and introduces its RNA into its cytoplasm. Next, the assembly of proteins and ready-made viral formations is started. After the formation of the viral nucleocapsid, the ready-made viruses leave the cell, merging with the outer membrane, and the cell itself dies.

In the external environment, standard strains of coronaviruses are not resistant: most of them die within a few hours. Under favorable conditions, these viruses can live up to 2 days. They are highly sensitive to household disinfectants (die in 2 minutes), drying, solar radiation, heating over 56 ° C (inactivated in 10-15 minutes).

More pathogenic and viable viruses are MERS-CoV, SARS-CoV, and SARS-CoV-2:

at room temperature, they can last up to 7 days in liquid sputum, up to 3 days on plastic and stainless steel, up to a day on cardboard, up to 4 hours on copper;

Under optimal conditions, they can persist up to 3 hours in the form of an aerosol, up to 4 days in urine and feces;

When frozen, viruses persist up to 3 weeks;

Slight heating (over 56 ° C) destroys them in no more than half an hour, 70% alcohol and 0.5% peroxide solution – in a minute;

Solar ultraviolet radiation shortens the life cycle of such viruses, but does not lead to their rapid inactivation. Quantization will destroy viruses more efficiently than natural ultraviolet radiation, but it can be used in the absence of people in the room, as they risk getting burned. K wart lamps are used only in medical institutions, operating rooms, laboratories. At home, for the prevention of coronavirus and other viral respiratory diseases, they are ineffective, and at high power they can be dangerous. For prophylaxis, it is recommended to treat the surface with an antiseptic with an alcohol content of 70% and disinfectants.

under laboratory conditions, freezing to -70 ° C and lyophilization at 4 ° C (gentle drying, freezing and placing in a vacuum) viruses persist for a rather long time [1] [3] [7] [9] .

Epidemiology

In total, about 40 types of coronaviruses are known (both pathogenic and non-pathogenic for humans). Most pathogenic forms of coronavirus constantly circulate among people around the world and cause mild ARVI – pharyngitis, tracheitis, bronchitis, etc. They arise in the winter-spring period due to the weakening of the body’s defenses and exacerbation of chronic ENT pathology.

For the first time, coronaviruses were discovered in 1965 by scientists D. Tyrell and M. Bino in a patient with ARVI. Until 2002, it was believed that coronaviruses can only cause mild respiratory infections in humans. However, since that time, the world has accumulated experience in the study of severe acute respiratory syndromes caused by coronaviruses. They provoked such diseases as:

SARS (caused by the SARS-CoV strain);

Middle East respiratory syndrome – acute respiratory infections, smoothly turning into severe viral pneumonia with respiratory and sometimes renal failure (caused by the MERS-CoV strain);

potentially severe acute respiratory infections COVID-19 (caused by the SARS-CoV-2 strain).

The SARS-CoV-2 coronavirus emerged recently : the first reports of the disease appeared on December 8, 2019. Presumably, this strain is a recombinant, i.e. a virus in which the genetic material is partially supplemented by the foreign genome of the bat coronavirus and an unknown coronavirus (possibly a snake or pangolin). The birthplace of the virus and the emergence of the disease is the city of Wuhan, located in the Hubei province of the People’s Republic of China. The primary source of infection is unknown. Presumably, the infection could have occurred in the market for seafood and exotic food (bats, snakes).

In a short period of time (about 2 months), the virus spread quickly enough and caused a pandemic – the World Health Organization announced this on March 11, 2020. Residents of Italy, Iran, South Korea and the United States were particularly affected.

Coronavirus: statistics in the world

As of March 1, 2021, the number of cases amounted to more than 114 million people (the leaders are the United States: more than 28 million, India: more than 11 million, Brazil: more than 10 million, Russia – more than 4 million), of which more than 2.5 million people have died (USA: more than 500 thousand, Brazil – more than 250 thousand, India – more than 150 thousand, Russia – almost 85 thousand). Mostly elderly people are seriously ill, for whom the virus is especially dangerous (up to 80% of all deaths).

Coronavirus in Moscow

As of February 28, 978,476 cases were detected in Moscow, 897,698 recovered, 15,055 died.

The prevalence of coronavirus (from 2.12.

The source of infection is sick people (from the end of the incubation period, including mild and asymptomatic forms of the disease) and dogs, but the risk of transmission of the virus from animals to humans is very low. The SARS-CoV-2 strain can potentially be transmitted from humans to pets, after which, after mutating, return back to humans. Now only the possibility of transmission of the virus from humans to cats and ferrets has been confirmed [12] .

Transmission mechanisms:

Aerosol:

Airborne droplets – when talking, sneezing and coughing at a distance of less than 2 m;

Air-dust path – when dust particles with virus particles get in;

Contact – when virus particles are transferred from infected areas of the body or objects to the eyes, mouth or nose after shaking hands, touching doorknobs, etc.

Fecal-oral – with anal-oral contact, cooking, non-observance of hygiene rules after latrines.

Transmission factors – air, dust, household items, and food contaminated with the virus. The closer and closer the contact between a healthy person and a sick person, the higher the likelihood of transmission of infection. Health care workers, people associated with close direct contact with people, and organized groups have an increased risk of infection.

Coronavirus transmission mechanism

In view of its instability in the external environment, any coronavirus cannot be transmitted through parcels from China under any circumstances. They go much longer than the possible period of survival of the virus on any materials.

While people do not have innate or acquired immunity to the new type of coronavirus SARS-CoV-2, therefore all people on the planet are susceptible to the disease. After the transferred disease, persistent humeral immunity is formed, but only to the serotype that the person has had. Therefore, re-illnesses caused by other types of coronaviruses are possible. After birth, the baby will inherit from the mother a short passive immunity for about a month and a half (sometimes a little longer with breastfeeding).

As with any ARVI, rare repeated cases of infection with the same type of virus are possible (in weakened patients or with a defective variant of antibody production, but this is rare).

Today, the average death rate from COVID-19 is around 5%. It is still quite difficult to predict the dynamics of this disease. The fact that some of the viral isolates have already become less pathogenic does not indicate a decline in the incidence, since large-scale testing for a new strain of coronavirus is not available in all countries. According to rough estimates, COVID-19 will actively spread for about 1.5-2 years until the overwhelming majority of people develop protective antibodies [1] [2] [6] [8] .

Warning

If you find similar symptoms, consult your doctor. Do not self-medicate – it is dangerous for your health!

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