Clinical FeaturesRespiratory

What to Know about the Acute Respiratory Viral Infections and the Flu?

“A wise person would rather avoid diseases, than pick drugs” Thomas More

Written by Tatiana Iarmak – http://

Lecturer of the Department of Advanced Training of Junior Medical Specialists at the Municipal Health Care Institution ‘Kharkiv Regional Medical Vocational College’, Kharkiv, Ukraine. An independent trainer, consultant to medical facilities and non-medical facilities to instruct medical staff on how to safely provide services to patients/clients.

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The aim of the study: Show the relevance of the problem of the infectious diseases, in particular, of the acute respiratory and acute respiratory viral infections, influenza; the influence of the type of the pathogen, seasonality, age, the state of the body’s immune system on the occurrence and the spread of the acute respiratory and the acute respiratory viral infections, influenza; the importance of prevention and immunoprophylaxis in preventing the occurrence and the spread of morbidity.

Brief summary: This article examines the dependence of the incidence of the acute respiratory and the acute respiratory viral infections, influenza, on the seasons of the year, the type of the pathogen, the ways of spreading of the infectious agents, immunity, lifestyle.


Infectious diseases remain one of the main problem for all the countries and pose a serious threat to the whole world. They have been known to the mankind since ancient times. In ancient Greece, Hippocrates laid down the foundations of epidemiology – a science which studies the patterns of the occurrence and the spread of the infectious diseases among people, the measures of preventing and combatting them; also, introduced the concept of “epidemic” and outlined it in his collection of books “Epidemics”.

In the 16th century, an outstanding Italian physician and astronomer, Girolamo Fracastoro, one of the founders of the modern epidemiology, the creator of the doctrine of infectious (contagious) diseases, singled out the concept of “infection” and three possible ways of infection: by contact with the patient, through the objects and through air (from the book “On contagion, contagious diseases and treatment “, 1546). He also developed the preventive measures, such as the isolation of the patient, a separate clothing for those caring for the sick; marking the doors of the houses with a red cross when there were contagious patients; the closure of the places of trade, restricting the visits to churches, etc. Much of the above is still relevant today. Only in the second half of the 18th century did epidemiology become a science with its own laws and rules, which are still being elaborated. The discoveries of the two outstanding scientists in the 19th – 20th century, the founders of microbiology and immunology: Louis Pasteur (France) and Robert Koch (Germany), proved the bacterial nature of the infectious diseases and laid down the foundations of the artificial immunity with the help of the vaccines, as well as the following researches of many other scientists in the field of microbiology and virology allowed to divide diseases into infectious, when the pathogen enters the human or animal body, and noninfectious. The 20th century was marked by a large number of discoveries of diseases of a viral nature. Viruses are widespread and very diverse. The ability of viruses to mutate – the variabilityleads to the emergence of the new strains and forms of diseases, the number of which increases every year. Currently, there are about 2 thousand infectious diseases. Infectious diseases (lat. “infectio”) is a group of diseases resulting from an interaction of a pathogen, a microorganism (bacteria, viruses, fungi, etc.), with a macroorganism – a human or animal body. In this regard, infectious diseases are divided into anthroponoses, which are inherent (peculiar) only in humans and zoonoses or zooanthroponoses, inherent in animals and humans. As a rule, infectious diseases are contagious, in other words, transmitted from person-to-person, and can quickly spread among people.

The most contagious and common are the infections of the respiratory system – the respiratory infections. The respiratory system consists of the lungs and the respiratory tract: nose, pharynx, larynx, trachea, bronchi and bronchioles and performs a huge number of functions – respiratory, gas exchange, protective, thermoregulation, hematopoiesis, deposition, voice formation, olfactory, ventilation, suction, filtration, water, lipid metabolism functions and more. The respiratory tract infections are divided into upper respiratory tract infections and lower respiratory tract infections. The upper respiratory tract is the nasal cavity, paranasal sinuses, pharynx and part of the larynx above the vocal cords. The upper respiratory tract infections: rhinitis, sinusitis, pharyngitis, tonsillitis, epiglottitis, rhinosinusitis, etc. The lower respiratory tract is the larynx, trachea and bronchi. Infections of the lower respiratory tract: laryngitis, bronchitis, bronchiolitis, bronchopneumonia. The infections, affecting the lungs, are pneumonia. Infections of the lower respiratory tract, in terms of the frequency of occurrence, are in the first place among the infectious diseases and in fourth place in the world in terms of mortality. Pneumonia is the leading cause of the early childhood death worldwide. In 2001, the pulmonologists from all countries organized a Forum of International Pulmonological Societies (FIRS). The societies included more than 70,000 professionals. The goal of the FIRS was to raise awareness of the population and the leaders of all the countries about the importance of the respiratory health, to develop the programs for a more effective prevention, improve the quality of an early detection of the respiratory diseases, and create a strategy to combat the respiratory system diseases, in particular, the respiratory infections. For a normal functioning, a person needs air (oxygen), water, sleep and food. Breathing is a vital necessity, therefore, the respiratory function is at the top of the list of human needs to stay alive. Without oxygen, an ordinary untrained person is able to hold out for 5-7 minutes, if longer, the irreversible changes occur in the cardiovascular system, in the brain – the oxygen starvation (hypoxia) of the vessels of the brain, and other organs, tissues, which leads to death. However, there is a category of people – freedivers, who use special techniques for training and can stay underwater for a long time (the record of 24 min. 33 sec. set in 2018 by a Croatian diver Budimir Šobat) at great depths without using professional equipment, with no oxygen, and without the detrimental consequences for their health.

About 90% of all infectious diseases are acute respiratory infections (lat. respiratiobreathing). This is the most common group of the diseases which causes the greatest economic damage to all the countries of the world compared to other infectious diseases. The acute respiratory infections or the acute respiratory diseases affect the organs of the respiratory system. They can be of various origin – bacterial, viral, fungal, etc. The respiratory infections are a specific type of an infectious pathology. They have a long seasonality – autumn, winter, spring; all age groups can get sick but more often these are children, who attend preschool institutions or elementary school. Immunity after an infection is short-term type-specific – only inherent in a certain type of the causative agent of a disease. The cold season is the most fertile time for the spread of the viruses, especially the respiratory viruses. The acute respiratory infections can be caused by one type of the pathogen, for example, only by a virus or a bacteriummonoinfection; by a combination of different types of only viruses or only bacteria – coinfection; by simultaneously the different types of pathogens: viruses, bacteria, fungi and others – mixed infection. The mixed infection often occurs in a more severe form, for a longer time, with complications, since the interaction of the pathogens often changes their properties, which can lead to disability and death. With co- or mixed infection, the infection occurs simultaneously (in parallel) with the different types of pathogens. There is also a concept of superinfection, when another infection (secondary infection) joins an already existing infectious process. Infection occurs, as a rule, at the stage of recovery, when the human body is depleted, immune forces and resistance are reduced. Secondary infection prolongs the course of the disease, worsens the patient’s condition, leads to complications, up to death. The most common bacterial pathogens are Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae Mycoplasma pneumoniae, Chlamydophila pneumoniae,

Legionella pneumophila, etc. Against the backdrop of a bacterial infection, the complications in a form of bronchitis or pneumonia may develop. The acute respiratory infection is caused by viruses: influenza, parainfluenza, rhinoviruses, reoviruses, adenoviruses, respiratory syncytial virus, coronavirus, etc. The respiratory syncytial virus is one of the main causative agents of the acute respiratory infections in children of the first 2 years of life (25%). Older children and adults are more likely to get influenza (40%-50%); and during an epidemic, the incidence rates rise up to 70%-90%. Currently, more than 300 viruses are known to cause the acute respiratory infection. More than 500 million people fall ill and more than 4 million die each year from the respiratory infections, especially in the countries with low living standards. About 40% of the respiratory infections in the cold season occur in a form of co-, mixed- and superinfections. Quite often, a viral infection, especially influenza, is complicated by a bacterial pneumonia; but in the last decade, the most common complication of the acute respiratory viral infection was the meningitis – an inflammation of the membranes of the brain and the spinal cord and the meningoencephalitis – an inflammation of the membranes of the brain and cerebral substance. Together with the acute respiratory infection, they significantly aggravate the patient’s condition and can lead to death. About 300 thousand people die every year from meningitis and every fifth person who has been ill with it develops the irreversible processes: hydrocephalus, mental retardation in children; epileptic seizures, psychosis, etc. WHO has classified meningococcal infection as a particularly dangerous infection. To prevent and control the meningitis, WHO has developed the first global roadmap, which sets out a concept and a strategy for the period up to 2030. When a viral infection is complicated by a bacterial infection, doctors often prescribe the antibiotic therapy. Unreasonable prescribing of antibiotics, as well as their sale without prescription in pharmacies leads to their uncontrolled use. The misuse of antibiotics is a major problem worldwide. About 50% of them are used not on purpose. About 1.3 million people die every year (WHO data) from infections, whose pathogens are resistant to antimicrobials. If the situation does not change, the annual number of deaths may increase up to 10 million (according to the WHO experts) by 2050, which will exceed the mortality from the cardiovascular and oncological diseases. On November 18, 2022 the World Antimicrobial Awareness Week took place under the auspices of the United Nations. Its organizers: the Food and Agriculture Organization of the United Nations (FAO), the United Nations Environment Program (UNEP), the World Health Organization (WHO) and the World Organization for Animal Health (OIE) presented the Multi-Stakeholder Partnership Platform to Combat Antimicrobial Resistance. WHO Director-General Tedros Adhanom Ghebreyesus said: “This platform will be critical in raising awareness of the issue… and gaining public support.”

Of all the acute respiratory infections, the most dangerous infection is the flu. The history of influenza begins in the ancient times. The great Hippocrates and the ancient Roman historian Titus Livy for the first time in 412 BC described the symptoms of the flu. Hippocrates also noted the seasonality: “All diseases occur at any time of the year, but some of them often occur and worsen at certain times.” The name “flu” appeared only in the 17th century and came from the French word “grippe”, which means “grab”, another name for the flu is “influenza” (flu) from lat. “intrude”. In 1933, at the National Institute for Medical Research in England, the British virologists Christopher H. Andrewes., Wilson Smith and Patrick Laidlaw outlined the first human influenza virus type “A”; T. Francis and T. Medgill discovered the type “B” influenza virus in 1940; R. Taylor influenza discovered the type “C” virus in 1947. Influenza type “A” viruses pose the greatest danger, causing epidemics and pandemics; influenza type “B” – epidemic outbreaks and epidemics, influenza type “C”more often sporadic incidence. The process of the emergence and the spread of the infectious diseases among people is called an epidemic process. According to the degree of intensity of the spread, the epidemic process manifests itself in the form of a) sporadic morbidity – single cases of the disease which are not epidemically related to each other; b) epidemic outbreak – an epidemically linked incidence, which affects a small group, for instance, a kindergarten or a larger group, such as a college or a university prom; c) epidemicmass morbidity of people, covering a locality or country; d) pandemic – mass morbidity of people, covering countries and continents.

The main route of transmission of influenza and the acute respiratory infection from a sick person to a healthy person is airborne. The acute respiratory infections are transmitted by the airborne droplets, which contribute to the rapid spread of the disease. When coughing, sneezing, talking, singing, and even breathing and yawning, the microparticles of saliva, mucus, sputum from the mucous membranes of the respiratory tract, enter the surrounding air and can be in it in a form of the fine aerosols, which poses the greatest danger within the radius of 2-3 meters in enclosed spaces. In a while, the aerosol settles down on the environmental objects (furniture, floor etc.), it remains there for a certain time (depending on the type of the pathogen); thus, a person gets infected by contacting the infected surfaces. Also, it can be transmitted by the household contact through the household items: dishes, dummies for babies, towels, bed linen. Moreover, influenza and the acute respiratory infections can be transmitted through the transplacental route (intrauterine – through the placenta), from a mother to the fetus during pregnancy and have a teratogenic (causes malformations) effect on the embryo and fetus, which can lead to various pathologies, congenital viral disease, death. In addition, a pregnant woman may be at risk of miscarriage or premature birth. In order to prevent the severe consequences of the acute respiratory infection and influenza in pregnant women, it is recommended to inform women about possible complications and carry out preventive measures before the pregnancy occurs.

The scientists from Trinity College Dublin, Ireland, together with the scientists from the University of Melbourne in Australia, have identified a mechanism of the occurrence of the dangerous complications in women during pregnancy, when infected with the influenza virus. Professor John O’Leary, who holds the position of the Professor/Chair of Pathology in Trinity College Dublin described the influenza virus as a “vascular storm”. The studies have shown that the virus provokes hyperactivity of the immune system, the long-term consequences of which can be manifested in a form of various diseases in the mother and child. “We will need more research to develop a specific antiviral therapy for pregnant women,” said Prof John O’Leary. To reduce the risk of the occurrence and the spread of the acute respiratory infections, it is necessary to carry out prevention. Prevention is divided into non-specific and specific. The non-specific prevention is aimed at strengthening of the immune system: daily routine, good sleep,

positive attitude, physical activity, a proper nutrition and drinking routine, walks in the fresh air etc. Also, the implementation of sanitary-hygienic and antiepidemic measures, especially in the cold season with an increase in the incidence of the respiratory infections: frequent washing of hands with soap or treating them with an antiseptic, since hands are the main factor in the transmission of an infection. Ventilation; wet cleaning of premises, including the door handles, switches, etc. with the use of the disinfecting solutions; treating phones and gadgets with an antiseptic; avoidance of the crowded places: public transport, theaters, concert halls, etc.; visiting medical institutions without necessity; going to a friend’s house when one is sick with the respiratory infection; staying home and not going to work or not taking children to school at the first signs of illness: runny nose, cough, fever will significantly reduce the possibility of infection and the spread of the acute respiratory infection. In public places, it is required to observe the “respiratory etiquette” – the rules of conduct aimed at limiting the spread of the respiratory diseases: – wearing a medical mask correctly – covering the nose and the mouth (reduces the risk of infection by 60% -80%). The mask was invented by the surgeons Johann MikulichRadetsky and Paul Berger at the end of the 19th century. During the Spanish flu pandemic of 1918-1920, the masks were used en masse for the first time;

– when coughing and sneezing, to use a disposable paper handkerchief or napkin and discard immediately after use;

– sneezing and coughing into the elbow bend in the absence of a handkerchief, not into the palms or fists of the hands, since the pathogens are transmitted from the hands to the objects – the door handles, switches, handrails, ATM buttons, trolley handles in a store etc .;

– treating hands with an antiseptic or the antiseptic wipes; – not touching one’s face with dirty hands, especially the mouth, nose, eyes.

A specific prevention – the immunoprophylaxis or a vaccination, is aimed at protecting against possible infection and reducing the risk of complications. In 1952, the WHO established the Global Influenza Surveillance and Response System (GISRS). The WHO Global Influenza Surveillance Standards were updated in 2013. The strategy of the system for the manufacture of the influenza vaccines with adaptation to the virus mutations allows to update the composition of vaccines every year and save millions of lives.


The acute respiratory infections, the acute respiratory viral infections, influenza are the most common diseases in the general structure of the infectious diseases worldwide. An early detection and isolation of patients; compliance with the sanitary-hygienic and anti-epidemic regime, especially during the seasonal periods of an increase in the incidence, compliance with the rules of the “respiratory etiquette”; targeted use of the antibiotics; prevention of the post-respiratory infectious complications in women during pregnancy, after childbirth, in newborns; the organization of the non-specific and specific preventive measures – immunoprophylaxis, can reduce the risks of the occurrence and the spread of the acute respiratory infections among the population, as well as lower the level of morbidity and mortality, especially among children.

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