Database of diseases - Flu and cold

 Sudden subcooling of the body due to the wind piercing clothing, rain sipping - these are typical circumstances during which immunity to cold and flu viruses decreases. The temperature corresponds best to 33-34 ° C, which is exactly the one that prevails in human nasal passages, while the ideal environment for their development is the nasal mucosa, to which they possess the possessive affinity.


The movement of airway epithelial cilia removes mucus and germs

The cilia of the epithelial sinuses nose and throat moving around 1000 times per minute, remove the mucus from the airways along with the impurities stuck at a speed of 3-25 mm / min. The physiologically fit "mucociliary" apparatus effectively removes cold and flu viruses without allowing them to infect the system.
 


INFECTIONS BY THE ROAD

Most often, colds and influenza viruses enter the airways through the "droplet"

For a time, there was a discussion about whether the infection with respiratory tract viruses is transmitted by droplets, or, for example, through "infected hands", foods and objects. Most studies show that the main route of infection is the "droplet" form. Every sneeze, a coughing attack, expels a sick cloud of volatile microscopic droplets of water that carries infectious viruses. This volatile secretion with aerosol properties - well known from cosmetics - in closed rooms is carried over long distances. It is believed that a few minutes spent in a crowded room with a cold person can infect a healthy person. It was found that the longer contact with a sick person - the higher the probability of infection and disease development.

What viruses cause colds?
 
Mainly we are infected with rhinoviruses, parainfluenza, coronavirus, adenovirus, coxatic viruses. The germ of the real flu is influenza A virus from the Ortomyxoviridae family.

What is the statistic of infections causing cold disease?

The so-called rhinoviruses. Epidemiological research on approx. 25,000 patients showed that they infect approximately 34% of patients; coronaviruses - 14%; Influenza viruses - 9%; parainfluenza viruses - only 3%. Only a few percent of cold diseases (2-10%) are caused by bacteria. Representative studies show that, in addition to viruses, the source of cold infections are mainly streptococcus inducing angina.
 
Everyone can be a virus carrier!

We should also know that some viruses in a small number and under the control of the immune system can be in the body and do not cause disease symptoms. For example, rhinoviruses colonize the human respiratory tract and many other colonizing digestive tracts, etc. Remember that the colds most closely correspond to the temperature of 33-34 ° C, which is exactly the way that prevails in the human nasal passages.

Weakness of immunity initiates cold disease

Even a summer longer subcooling or rain soaking can weaken the physiological covers and the immune response to the virus attack. This usually suffices for the microorganisms to use their extraordinary ability to penetrate into the epithelial cells of the nasal and pharyngeal mucosa. Initially, the microorganisms multiply in the cells of the lymph glands to then attack the ciliated epithelial cells lining the airways. The attack allows suitable membrane receptors to facilitate the penetration of viruses into the epithelial cell. In their interior, viruses multiply intensively, using the human genetic mechanism for this purpose.
 
Viruses are capable of destroying a large number of cells of the nasal mucosa and throat.

The destruction of the epithelial cells results in acute inflammation of the mucous membrane and, consequently, in the abundant release of irritating substances - called inflammation mediators - e.g. bradykinin, tachikin, and to a lesser extent histamine and prostaglandins. Mediators cause the expansion of small blood vessels (capillaries) and flaccidity of venous walls, with their abundant blood filling. The disease is caused by seepage of the capillary blood plasma and pain and pruritus of the mucous membrane. Following viral invasion, some epithelial cells become necrosis and exfoliation. In addition, ciliary cells that remove mucus with viruses and impurities entering the nose as well as goblet cells that produce important defense substances are damaged.

The temperature rises - there is a fever

Inflammation of the mucous membrane brings numerous immune cells, including large and voracious macrophages - "garbage trucks" for germs. Macrophages absorb viruses into their interior and destroy them there. Stimulated with their activity, they begin to secrete the so-called endogenous pyrogens - substances that cause an increase in body temperature - or fever - the primary symptom of inflammation.


Fever

Although it is an important signal of the beginning of the inflammatory process and indirectly indicates the efficiency of defense mechanisms, too high temperature - exceeding 39 C - is an unfavorable phenomenon. It increases catabolism, which in young children can cause fever convulsions accompanying viral infections. Therefore, after establishing the diagnosis, too high a fever should be fought. It should be emphasized that despite the widely accepted belief, neither the presence of fever nor its height, does not testify to the initiation of bacterial infection, and can not be the sole indication for initiating antibiotic therapy.




Warning! Symptoms of refractory rhinitis can be caused by allergy

Symptoms of viral and non-infectious rhinitis are similar in different disease syndromes. These are, as we have already pointed out, congestion of the mucous membrane, leakage of secretions, pressure or sinus pain and periodically, pruritus and sneezing. Unfortunately, the effects of inflammation are similar - they rely on the destruction of the ciliary-mucosal apparatus self-cleaning the nose with germs. To differentiate treatment - you need to identify allergies. Hay fever differs from the cataracts of the cold caught by the viral absence of fever, lack of the phase of thickening serous secretion from the nose and self-healing after 5 days of infection, etc. However, allergy tests are the best way to differentiate allergic and non-allergic rhinitis. Skin tests and tests to determine the level of IgE in blood serum can also be performed.


The expansion of viruses in the nasal mucosa intensifies the symptoms of a cold

Destruction of the mucous membrane by viruses releases a number of other mediators and, such as: prostacyclin, prostaglandins (especially PGD 2), leukotrienes (LTC4, LTD4 and LTF4), phosphatidylcholine (PAF), histamine, bradykinin, nitric oxide. This causes small vessels to dilate, increase their permeability, and expel blood plasma. The result is swollen tissue irritability of the bronchial mucous membrane, etc.


This extremely unpleasant period of viral infection, called the serous-exudative phase, usually lasts from 2 to 5 days.

The sensation of the feeling of nasal congestion, hearing impairment, headache, muscle pain, difficulty in swallowing, dry torment cough and abundant nasal secretion, burning and watery eyes are becoming symptoms.

After this period, there is a phase of thickening of the serous secretion.

The key role in the development of the second phase of viral infection is played by tissue hormones - prostaglandins and others, eg inactivating tachykinins and bradykinin and spontaneous physicochemical phenomena leading to the increase of mucus viscosity. Drying of the secretion plays an extremely important role in this process. This second period of viral infection, called thick obturation phase, usually takes 2-3 days.


In the second period of infection, bacterial superinfection with bacteria normally colonizing the respiratory tract is particularly easy.

In the viscous, thick mucus, the bacteria find excellent conditions for massive multiplication. However, if the defense forces are sufficient, the multiplication of the bacteria is stopped. Mucositis is also inhibited - stimulated by mediators of inflammation, destroying the action of viruses, etc. Cold disease begins to self-heal: respiratory secretions liquefy, and inflammation extinguish.


Ed.Edward Ozga Michalski, MA

CONTENTS AND ACCESS TO ARTICLES OF THE SECTION:
Frequent cold virus infections
Mechanisms for the defense of the nose and throat
Individual resistance to cold viruses
The immune system of a young child
Self-amplification of immunity in infants and young children
Natural strengthening of immunity in infants and young children
Diet and immunity

Literature:
1 / Cold and its treatment - prof. dr hab. med. Andrzej Danysz, A. Kwieciński, Nowe Leki, 1996
2 / Treatment of colds - Piotr Albrecht, Andrzej Radzikowski from the Pediatrics Clinic of the Medical Academy in Warsaw
3 / Inflammation of the paranasal sinuses in children; dr n. med. Jarosław Wysocki, medicine med. Adam Chusteczki; - "Służba Zdrowia" No. 90-93 / 2001
4 / Medycyna Praktyczna 2002/07: Guidelines - Allergic rhinitis and its effect on asthma
5 / Inflammation of the mucous membranes of the nose and throat in children - prof. dr hab. med Grażyna Niedzielska Medycyna Rodzinna 8 (4/1999)
6 / Influenza vaccines - Statement by prof. dr hab. med. Lidi Brydak, lapharma.info 2002.
7 / Attitudes of Medical Microbiology - PZWL, 1994
8. Inflammation of the mucosa of the nose and throat in children - prof. dr hab. med Grażyna Niedzielska from the Department of Pediatric Otolaryngology, Phoniatrics and Audiology, Medical Academy in Lublin; Medycyna Rodzinna 8 (4/1999)