When we breathe, not only does oxygen get into our respiratory tract, but also a wide variety of particles that are contained in the air around us. This also includes pollutants and pathogens that can cause infections in the respiratory tract. The airways are constantly in contact with pathogens such as viruses and bacteria. No wonder, then, that respiratory tract infections are among the most common diseases. The good news: In contrast to chronic respiratory diseases , acute respiratory infections are usually short-lived.
What is a respiratory tract infection?
A respiratory tract infection is inflammation of the airways caused by pathogens. Depending on which area of the respiratory tract is affected, infectious respiratory diseases are divided as follows:
- One speaks of an infection of the upper respiratory tract when the nose, sinuses and/or throat are affected.
- Infections of the lower respiratory tract affect the larynx, trachea and/or lungs including bronchi.
Usually, the inflammation is not limited to one area of the airways, but rather spreads. In the case of a cold, for example, the nose, sinuses and throat are usually affected, sometimes also the middle ears. Typical consequences are therefore, among other things, coughing runny nose, sore throat and earache. If the inflammation spreads to the bronchial mucosa, acute bronchitis occurs .
Frequency of RTI
The most common respiratory tract infections include the common cold, the flu , Covid-19 , acute bronchitis , sinusitis and pneumonia . The human respiratory syncytial virus ( RSV ) is also a pathogen that often affects the respiratory tract and can hit children particularly hard. Every adult gets an average of two to four colds a year, and children even more often. The flu affects several million people in Germany during a seasonal flu epidemic.
Respiratory tract infection: causes
The causes of respiratory infections are pathogens such as viruses or bacteria that penetrate the respiratory tract and multiply there.
The respiratory tract comes into contact with these pathogens on a daily basis. Normally this is not a problem: the respiratory tract is lined with a protective mucous membrane that prevents the virus or bacteria from entering the body. In addition, the body has an immune system that can eliminate invaders before they become dangerous.
However, especially in autumn and winter, various influences can cause these protective mechanisms to fail:
- Cold can weaken the immune system.
- Dry heating air irritates the mucous membranes of the respiratory tract.
- In addition, influenza pathogens, for example, are more stable at low temperatures and in dry air.
Other circumstances can also temporarily weaken the body’s defense system and thus promote respiratory infections, for example lack of sleep or heavy physical exertion.
The typical symptoms that respiratory tract infections lead to – runny nose, coughing and difficulty swallowing such as a sore throat – arise because the body fights the infection: in order to get rid of the pathogens, the mucous membranes produce more mucus. Immune cells that migrate into the mucous membranes also cause them to swell.
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Which pathogens can cause respiratory infections?
There are many types of viruses and bacteria that can cause respiratory infections. Here is an overview of the causes of the most common respiratory infections:
- Colds are usually caused by an infection with rhinoviruses ( rhino = nose). These attack the mucous membranes of the nose and throat and multiply there. The common cold is caused by more than 200 different types of viruses. A cold is often accompanied by inflammation of the bronchial mucosa, i.e. acute bronchitis.
- Covid-19 is caused by the SARS-CoV-2 coronavirus .
- The flu (influenza) is caused by influenza viruses.
- In the case of infectious pneumonia (pneumonia) , various bacteria, viruses or fungi can be considered as causes. Bacteria of the genus Streptococcus pneumoniae (pneumococci) are often responsible for the inflammation of the lung tissue.
- Whooping cough is caused by bacteria of the genus Bordetella pertussis – hence the technical term pertussis.
- Scarlet fever is a childhood disease that occurs as a result of infection with streptococci – also bacteria.
- Tuberculosis is caused by bacteria of the genus Mycobacterium tuberculosis .
Acute respiratory infections
An acute infection usually subsides on its own after 1-2 weeks and can affect the mucous membrane of various areas. Depending on the affected area, different subtypes of respiratory infections can be defined:
Upper respiratory tract infections
- Inflammation of the nasal mucosa (rhinitis)
- Inflammation of the paranasal sinuses (sinusitis)
- Middle ear infection (otitis media)
- Inflammation of the larynx (laryngitis)
Respiratory infections of the lower respiratory tract
- Inflammation in the throat (pharyngitis)
- Inflammation of the windpipe (tracheitis)
- Inflammation of the bronchi (bronchitis)
- Inflammation of the air sacs in the lungs (alveolitis)
- Pneumonia (inflammation of the lung tissue = pneumonia)
As a rule, however, an infection of the respiratory tract affects several areas at the same time. The designation is then chosen according to the relevant area affected.
Chronic respiratory infections
If the respiratory tract is under constant strain, respiratory tract infections can also take a chronic course. A respiratory infection becomes chronic when the symptoms keep recurring or hardly or not at all subside.
Chronic upper respiratory tract infections
In the upper respiratory tract, it is primarily various forms of chronic sinusitis that cause problems for many sufferers. They suffer from recurring respiratory infections in the sinuses of the nose, often have headaches and often feel tired or exhausted.
The causes are often of an allergic or anatomical nature. An allergic cold, for example, can cause chronic infections in the paranasal sinuses and keep the patient in check at all times. But bottlenecks in the area of the sinuses also disrupt the flow of mucus and quickly lead to the spread of pathogens.
In the case of chronic infections of the upper respiratory tract, there is always a risk of the inflammation spreading to the lower respiratory tract . If the mucus can no longer drain through the nose, this often leads to what is known as postnasal drip syndrome . In this phenomenon, mucus flows down the throat into the bronchi, where it can be involved in the development of a chronic lower respiratory tract infection.
Treatment of respiratory infections
For most viral respiratory infections, treatment aims to relieve symptoms. In the case of a cold, for example, decongestant nasal sprays can help against a blocked nose. A dry cough can be relieved with medications that contain codeine .
Even with the flu, those affected usually only receive symptom-relieving medication. For example, cough syrups and nose drops can be useful. Medication containing acetylsalicylic acid can also help with fever and headaches.
Respiratory tract infection: course & duration
The duration and severity of a respiratory infection depend on which pathogen caused it and which area of the respiratory tract is inflamed:
- With a cold, the first symptoms usually appear two to four days after infection and subside after a week at the latest.
- An infection with influenza viruses is often without strong symptoms, but it can also be severe. If more severe symptoms occur, they usually start very suddenly. Influenza usually lasts about one to two weeks.
- Pneumonia caused by bacteria is usually accompanied by severe symptoms such as shortness of breath , which usually occur suddenly and can have dangerous consequences, such as lack of oxygen. Timely treatment with antibiotics is therefore important.
This article is based on complete information Respiratory Tract Infection: Symptoms, Treatment & Course