Cold virus

it is a viral disease that affects the upper respiratory tract; the infectious process that sustains it causes inflammation of the nasal mucous membranes, throat and bronchi, manifesting itself with a typical procession of symptoms: stuffy nose that drips mucus (rhinorrhea), sore throat, headache, cough, loss of appetite and sensation of general malaise.

What Causes the Cold

Among the more than 200 viruses potentially capable of causing the disease are often implicated in the onset of colds. Among these, the most common are represented by:

1. Rhinovirus (30-80% of cases)
2. Coronavirus (10-15%)
3. Influenza viruses belonging to the Orthomyxoviridae family (5-15%)
4. Human parainfluenza viruses (1-3%)
5. Respiratory syncytial virus
6. Adenovirus
7. Enterovirus
8. Metapneumovirus

Often, the viral infection is superimposed after a few days by a secondary bacterial infection, which can complicate the cold in tracheitis, bronchitis, otitis, sinusitis or bronchopneumonia. Only in this case can the use of antibiotics be useful and necessary, which - let us remember once again - are contraindicated in the treatment of uncomplicated viral diseases.

For further information: Colds or to the eyes, without having washed it first.

The transmission of cold viruses through aerosols or droplets of Flügge (droplets), occurs through micro drops of saliva (water vapor) emitted through coughing and sneezing, which remain suspended in the air carrying the infectious agents.

For further information: Droplets: Meaning, Distance, Dimensions and Transmitted Diseases

Cold: when is it most common?

Most of these viral infections arise in the cold season, from autumn to early spring.

There are generally three infectious waves per year:

• One in autumn, immediately after the reopening of the schools;
• One in mid-winter;
• A third in spring.

Probably this occurs due to the longer stay in closed and promiscuous places (schools), which favors the transmission of cold viruses both by direct contact with contaminated surfaces, and by transport of microorganisms in the form of aerosols. For this reason, the spread of cold viruses is greater in both military and civilian communities (shelters for the elderly, nursery schools, school classes, etc.). In addition, the paralyzing effect of cold on the cilia lining the respiratory epithelium must be considered, fixing and retaining foreign bodies, filtering the air and facilitating the expulsion of the mucus and the microorganisms incorporated in it. Cold viruses, in turn, lead to the destruction of eyelashes and hair cells, facilitating bacterial superinfections.

acute nonspecific. These RNA viruses are characterized by their small size (30 nm diameter) and cubic symmetry; they grow at a temperature of 33-34 ° C, the same as in the human nasal mucosa.

To date, more than 100-150 serologically distinct types of rhinovirus are known; while leaving type-specific permanent immunity, infection with one type of virus offers no protection against the other types; in fact, the cross protection between the various serotypes is very low or zero, and this explains why young children experience on average from 5 to 10 episodes of colds a year, especially during the second year of life and in the autumn, winter period. and spring, precisely in the period in which nursery schools are most frequented. The adult, on the other hand, has an average of two to four respiratory infections a year, accompanied by colds.

The incubation period is typically 12-48 hours.

Rhinovirus colds occur most frequently in the fall and late spring.

(SARS-Coronavirus), which can cause serious infections of both the upper and lower respiratory tract: in 2002, especially in China, it caused a serious epidemic of acute respiratory syndrome.

The incubation period is typically 1-7 days.

Unlike rhinoviruses, reinfections with the same type of virus are more common.

Coronavirus colds occur most frequently in the winter months.

, chills, malaise, body aches and nausea.

The influenza A virus is subject to periodic variations of the antigens; the greatest and most dangerous variations occur every 10-30 years and are responsible for real pandemics, finding fertile ground in an immune system that - having never encountered the virus - is not very active towards him.

, wheezing (shortness of breath) and croup.

Contrary to influenza viruses, they do not undergo antigenic variations, so in the immune subject (adult) they cause modest symptoms, mostly limited to colds or rhinolaryngitis.

The incubation time is 3-6 days.

more important than respiratory infections in children, being the main cause of childhood bronchiolitis and pneumonia. It is an RNA virus, with a diameter of 120-300 nm, which presents helical symmetry. In the adult it causes very mild or even inapparent infections.

See also: Syncytial Respiratory Virus - RSV, gastroenteritis, cystitis and pneumonia. Once again, children are most at risk, while the disease is rarer in adults. Adenoviruses contain bicatenary DNA, have an icosahedral structure and have a diameter of 70-80 nm. There are five human serological types.

; more rarely, the infection develops in the respiratory system, mainly along the upper airways.

Most often, these viruses attack weak individuals or individuals with compromised immune defenses, such as children or people in rehabilitation after illness or trauma. Poliovirus, an etiological agent of poliomyelitis, also belongs to this kind of virus.

, right after the respiratory syncytial virus. The elderly and immunosuppressed individuals may also be affected.