Lower Respiratory Tract Infections

Lower Respiratory Tract Infections

Respiratory tract infections (RTIs) are caused by viruses and bacteria. They affect respiratory tract and are believed to be the most common reason why people visit their GP. There are numerous respiratory tract infections, ranging from the mild conditions such as common cold to the more serious ones like pneumonia.

Unlike upper respiratory tract infections that affect the nose, sinuses and throat, lower respiratory tract infections (LRTIs) affect the lungs and airways and can develop into more severe conditions, in some cases even leading to death.

The most common and most severe LRTIs include:

  • pneumonia
  • bronchitis
  • tuberculosis

What is very characteristic of LRTIs and RTIs in general, is that the less serious conditions (for example, bronchitis) can lead to the more dangerous ones like pneumonia. That is why they need to be treated in a timely and adequate manner.


Pneumonia primarily affects the lungs. It is an inflammatory condition that fills the sacs known as alveoli with pus and fluid. As a result, the infected person has difficulties breathing and limited oxygen intake.

Pneumonia is caused by many different bacteria, viruses and fungi. The most common causes are:

  • Streptococcus pneumoniae(most common bacterial cause)
  • Haemophilus influenzae(second most common bacterial cause)
  • respiratory syncytial virus (most common viral cause)
  • Pneumocystis jiroveci (one of the most common causes in HIV-infected infants)

This disease is transmitted by inhaling the bacteria and viruses commonly found in nose and throat, through air-borne droplets from a cough or sneeze, as well as through blood, particularly during and shortly after birth.

Cough, fever and difficult breathing are all common symptoms, but the most certain symptoms of pneumonia are either fast breathing or lower chest wall indrawing while breathing. Other symptoms include wheezing, and in severe cases, inability to eat or drink, unconsciousness, hypothermia and convulsions.

HIV-infected children and those who live in crowded spaces where indoor air is polluted or there is a lot of tobacco smoke are particularly at risk of contracting this disease. Therefore, the best way to prevent pneumonia is by improving the living conditions as well as strengthening one’s immune system. Also, immunization and proper nutrition are methods that considerably reduce the risk of catching this disease.

Pneumonia is best treated with antibiotics (most commonly amoxicillin), while hospitalization is required only in the most severe cases. If left untreated, pneumonia can result in severe conditions such as respiratory or circulation failure and sometimes even death.


Acute bronchitis is usually a viral infection that causes inflammation of the bronchi in the lungs. It can be transmitted through the air when infected people cough or through direct contact with them.

People who are exposed to dust, tobacco smoke and other air pollutants are particularly at risk. Acute bronchitis is also known as chest cold and the most common symptom is a cough that lasts for about three weeks. Other common symptoms include:

  • coughing up mucus
  • wheezing
  • shortness of breath
  • fever
  • chest discomfort

The infection may last from a couple to ten days, while the symptoms may persist for up to six weeks.

Bronchitis is best prevented by not smoking and avoiding other lung irritants. It is best treated with paracetamol, rest and non-steroid anti-inflammatory drugs (NSAIDs) to reduce the fever.

On the other hand, chronic bronchitis is a persistent productive cough. People who have cough for three months per year on a regular basis should be examined for chronic bronchitis. Also, chronic obstructive pulmonary disease (COPD) is characteristic for most people with chronic bronchitis.

This type of bronchitis is usually caused by tobacco smoking, while the less common causes are asthma, air pollution and genetic predispositions.

The most effective treatment methods are quitting smoking, rehabilitation, vaccination, inhaled bronchodilators and steroids. In some cases, long-term oxygen therapy and lung transplantation may be useful.


Tuberculosis (TB) is usually caused by the Mycobacterium tuberculosis (MTB). It is an infectious disease which generally affects the lungs.

Tuberculosis is spread through the air when infected people release the TB germ in the air by sneezing, coughing, spitting or speaking.

In case of latent tuberculosis, the TB bacteria remain in the body in an inactive state. People with latent TB are not contagious and have no symptoms. However, in people with active TB, bacteria do cause symptoms and are highly contagious. These people need to receive proper treatment to cure the disease and prevent further complications.

Similar to pneumonia, HIV-positive people are at higher risk of contracting tuberculosis due to the weakened immune system.

The symptoms of active tuberculosis are:

  • chest pain
  • cough with sputum (and sometimes blood)
  • fever
  • chills
  • weakness and fatigue
  • weight loss
  • night sweats
  • loss of appetite
  • nail clubbing

The best method to diagnose TB is the rapid test Xpert MTB/RIF, while the treatment is based on taking antimicrobial drugs for at least 6 months.

Key Facts About the LRTIs

  • Pneumonia is caused by viruses, bacteria or fungi. It can be prevented by immunization, proper nutrition and improving environmental factors.
  • Pneumonia is responsible for over 15% of deaths of children under the age of five.
  • Chronic bronchitis (or COPD) accounts for over 3 million deaths a year worldwide. Also, it is estimated that there were 251 million people with COPD in 2016.
  • In 2016, 10.4 million people contracted tuberculosis and 1.7 million died from it.
  • In the same year, 1 million children contracted TB and 250,000 died from it.
  • HIV-infected people are at higher risk of contracting pneumonia and tuberculosis due to their weak immune system.
  • Low- and middle-income countries, particularly those in sub-Saharan Africa, are the most affected by lower respiratory tract infections.


Lower respiratory tract infections are complex and serious conditions even though most of them start in a seemingly harmless way. Nevertheless, if people don’t receive timely and proper treatment, complications are bound to happen, sometimes even resulting in death.

It is important to note that the third-world countries account for the biggest number of LRTI cases. Weak immune system and poor living conditions are the main culprits. However, immunization, nutrition and improving environmental conditions can lead to a significant decrease in the number of new infections.

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