Most often, a typical coronavirus infection is asymptomatic or leads to the development of subtle symptoms (Symptoms of a coronavirus infection) like acute respiratory infections with damage to the nasal cavity and pharynx. There is lacrimation, tickling in the nose, runny nose with abundant mucous discharge, impaired sense of smell, perspiration or mild sore throat, dry cough (after a while – with a small amount of sputum). The patient feels unwell, weakness, chills, moderate headaches are possible, an increase in body temperature by no more than 38 ° C. In children, signs of damage to the digestive tract in the form of abdominal discomfort, unstable stool, and nausea may join all of the listed symptoms. Within a week, the severity of symptoms decreases and recovered.no. Sometimes the disease manifests itself with only slight weakness, even with damage to about 25% of the lungs, which is visualized only on a CT scan of the chest.
Unlike year-round forms of coronavirus infection, highly pathogenic forms of the disease manifest themselves much more severely, their prognosis of 20% is very serious.
The most common symptoms of COVID-19 are:
An increase in body temperature up to 38 ° C;
Loss of taste and smell;
Some patients may experience pain in muscles and joints, runny nose, nasal congestion, decreased or disappearance of smell, sore throat, moderate diarrhea. Usually, these symptoms develop gradually and are mild.
Most of those infected do not develop any serious symptoms or feel unwell, as with other forms of coronavirus infection. In 80%, the disease ends in complete recovery.
In about one in six cases of COVID-19 (mainly in elderly and weakened people with concomitant diseases), severe symptoms develop with the development of respiratory failure:
Fever and cough increases;
Shortness of breath, atypical type of breathing appears;
Weakness is growing;
Possible chest pain when breathing and coughing, abdominal pain and tachycardia;
Lips and nose become bluish;
Disturbance and confusion of consciousness is possible.
All of these signs may indicate developing pneumonia or respiratory distress syndrome of the lungs. In these cases, urgent hospitalization is required in the intensive care unit and intensive care unit. The time from the onset of symptoms of COVID-19 (with confirmation of the pathogen) to death in severe cases ranges from 6 to 41 days (average 14 days).
Coronavirus infection in pregnant women. So far, there is no comprehensive data on the specific negative impact of coronavirus infection and COVID-19 infection, in particular, on the outcome and course of pregnancy, the condition of the fetus and child, and the development of intrauterine pathology. However, the course of the disease with a new coronavirus infection is quite difficult.
Coronavirus infection in children. Children tend to tolerate the disease more easily than adults. In some cases, pneumonia may develop. It usually occurs in children with a burdened background for colds or pulmonary pathology.
Also, the disease can develop in newborns. Basically, the virus is transmitted from mother to child after childbirth through the respiratory tract. A severe course of the disease in such cases is rarely observed.
Pathogenesis of coronavirus infection
Entrance gates – epithelium of the upper respiratory tract, epithelial cells of the stomach and intestines. The coronavirus enters cells that have type II angiotensin-converting enzyme (ACE2) receptors, where it accumulates and multiplies. From the nasopharynx, the virus spreads through the blood vessels, affecting the cells of the lower respiratory tract, stomach, intestines, penetrating deeper into the tissue. In most cases, this process is self-limited, which leads to a complete recovery as a supply of protective antibodies is formed in the body.
When infected with COVID-19, viruses can continue to be shed even after some time after they have disappeared from the respiratory tract. This indicates the likelihood of a later fecal-oral transmission mechanism of the disease.
With the simultaneous absence of immunity to infection and the presence of immunodeficiency against the background of concomitant diseases, the virus can break through the immune defense and massively spread through the tissues of the body. This, for example, occurs when infected with a new strain of SARS-CoV-2. The spread of infection leads to a cascade of pathological reactions, during which damage to the alveoli progresses, severe respiratory failure occurs and death occurs. This can be schematically represented as follows:
In response to the inflammatory process, pro-inflammatory factors are formed that activate alveolar neutrophils and macrophages – cells that devour foreign and unnecessary substances;
Neutrophils attach to the inner surface of the pulmonary capillaries and cause a cytokine storm: they release cytotoxic factors (including aggressive oxygen compounds) that damage the walls of small alveolar vessels.
Due to vascular damage, the inflammatory fluid (exudate) penetrates into the air pulmonary space itself, which leads to hypoxia – oxygen starvation;
Also, due to cell damage, the production of surfactant is disrupted – a substance that prevents the alveoli from collapsing.
Against the background of the collapse of the alveoli, hypoxia increases, the vital capacity of the lungs decreases. As a result, blood clots form in the pulmonary artery, pulmonary hypertension develops – an increase in pressure in the pulmonary circulation. Severe pulmonary hypertension can lead to heart failure and death.
The virus affects the human body in the same way, regardless of age. The danger for the elderly and weakened people lies only in the imbalance of the body’s work and the deterioration of existing chronic diseases. The same happens with other pathogens of respiratory infections, such as the flu . However, the danger of the new coronavirus lies in the more frequent development of complications due to the complete inability of the immune system to resist a pathogen unknown to it.
Classification and stages of development of coronavirus infection
There are four degrees of severity of coronavirus infection:
Light – It is accompanied by normal or slightly high body temperature, weakness, runny nose, sore throat, rare cough;
Moderate – lasts up to 10-12 days. It is accompanied by a moderately elevated body temperature up to 38 ° C , severe weakness, headache, runny nose, sore throat and sore throat, dry cough, sometimes with moderate sputum production;
Severe – lasts more than 2 weeks. It is accompanied by high body temperature, severe weakness, nausea, dizziness, severe cough (dry and with phlegm), chest pain, shortness of breath;
Extremely severe – most often it develops against the background of a serious illness, has an unfavorable prognosis. Accompanied by progressive shortness of breath, tachycardia, lowering blood pressure, blue lips and nose;
Diseases caused by potentially dangerous types of coronavirus are divided into three groups according to their clinical form:
Mild acute respiratory infections, accompanied by damage to the upper respiratory tract (nose and pharynx);
ARI, accompanied by pneumonia without a threat to life;
ARI, accompanied by severe pneumonia with the addition of acute respiratory distress syndrome.
Complications of coronavirus infection
Pneumonia. The body temperature rises sharply, the cough intensifies, phlegm is released (when secondary bacterial blood is added, it acquires a greenish-yellow tint, sometimes brownish streaks can be noticed), chest pains occur during coughing on the affected side and shortness of breath, weakness and headache increase, possibly the appearance of neutrophil leukocytosis in the peripheral blood (an increase in the number of neutrophils).
Acute Respiratory Distress Syndrome. It develops within 2-6 days from the onset of the disease. It is characterized by an increase in dry cough, shortness of breath, the appearance of rapid shallow breathing, the participation of auxiliary muscles during breathing, tachycardia, blue lips and nose, a progressive decrease in the level of oxygen in the blood below 90%, a violation of the acid-base balance in the body. When listening to the lungs, wheezing is possible, with radiography – infiltrates in the lungs, pleural effusion. The prognosis is often poor.
Multisystem inflammatory syndrome. It develops in children and people under 21 years of age. It is manifested by prolonged fever with a temperature of more than 38 ° C, inflammatory changes in most body systems and an increase in the level of inflammatory markers (C-reactive protein, ESR, procalcitonin, fibrinogen, etc.).
Diagnostics of the coronavirus infection
A clinical blood test reveals immune reactions. With coronavirus infection, there are signs of a standard viral disease: a decrease in the level of leukocytes (up to absolute leukopenia) or normal size of red blood cells, a decrease in the level of neutrophils, eosinophil and platelets, an increase in the number of lymphocytes and monocytes.
A general urinalysis is usually unchanged. With the development of severe forms of the disease, proteinuria and cylindruria (the appearance of protein and cylinders in the urine) are observed.
A biochemical blood test evaluates the functional activity of organs. It is possible to increase ALT, AST, C-reactive protein, creatinine, pro-inflammatory cytokines, and lactic acid and procalcitonin – a marker of sepsis (predictively indicates an unfavorable course of the disease).
RIF – the reaction of immunofluorescence for the detection of antigen. The material for the study are smears-prints of the nasal mucosa or nasopharyngeal discharge, which are taken using a special sterile swab.
ELISA – enzyme-linked immunosorbent assay for the detection of specific antibodies (IgM and IgG). For research, blood is taken from a vein twice with an interval of 10-14 days.
Interpretation of test results:
Both classes of antibodies are negative – most likely, the person has not yet had a coronavirus infection, but may get sick (repeated tests are needed);
Only IgM is positive – the patient is currently suffering from an acute infection;
Both classes of antibodies are positive – a person has been sick for a long time;
Only IgG is positive – the subject has been ill for a long time and has immunity.
It is not worth making an affirmative diagnosis only on the basis of ELISA results.
PCR diagnostics allows you to determine the type of virus by detecting RNA. In the case of SARS-CoV-2, the diagnostic material (smear) is taken from the nasal cavity and oropharynx, less often blood, urine and feces are used. The test results will be known in 3-4 hours.
PCR results should be evaluated in conjunction with ELISA:
If the PCR is positive, then with a high probability at the moment the person is suffering the disease (quarantine is needed);
If the PCR is negative and IgM and IgG antibodies (or only IgG) are detected, then we can talk about a previous illness and the absence of an epidemiological danger (quarantine is not needed).
Sometimes a control PCR after a negative PCR result in a previously confirmed case of coronavirus infection shows a positive result. This is possible in a small number of cases: when viral particles are actually present in the body, and their concentration will be much lower than the previous one (when the person was in the midst of an illness), or when the test system reacts to a non-viable virus. Such people, most likely, do not pose an obvious danger to others, but there is not enough data for definite conclusions.
Cultivation of the virus on a mouse cell culture – virus isolation in specialized laboratories.
X-ray examination allows you to detect infiltrates in the lung tissue with pneumonia, for example, of the “ground glass” type.
Computed tomography can also reveal pneumonic changes, including at the initial stages.
Changes in the lungs during coronavirus infection COVID-19 (CT scan)
Medical examination for the new coronavirus SARS-CoV-2 must be passed by people who have arrived from areas unfavorable for the disease, have been in contact with patients or have symptoms of acute respiratory infections. This can be done at an accredited health center at your place of residence.
There are no specific symptoms that distinguish coronavirus infection from other acute respiratory infections. What matters is only the combination of symptoms from the epidemiological situation of coronavirus infection in the region, the fact of contact with sick people and visiting a country that is unfavorable for this disease.