Common Respiratory Tract Infections (RTI)


Published: 06 April 2020

Respiratory tract infections (RTIs) are extremely prevalent, accounting for 20% of medical consultations and 30% of lost work days. Not at all trivial, RTIs contribute to 20% of mortality in children under five in developing countries (WHO, cited in Reed 2015).

With the current state of pandemic, the following article aims to help re-familiarise you with the different symptoms and presentations of the most commonly seen respiratory illnesses so that you can be confident in the care you provide.

(Important: If you or someone you know is currently displaying cold or flu-like symptoms such as cough, sore throat, headache, fatigue or shortness of breath, you must self-isolate and seek medical help. Contact your doctor’s clinic or emergency room before visiting for protocols. For further information, use the Healthdirect Australia Symptom Checker, available here.)

What is an RTI?

Respiratory tract infections (RTIs) are respiratory illnesses that refer to a variety of infections of the sinuses, throat, airway or lungs (NHS 2018).

RTIs are separated into two categories depending on the area of the respiratory system they affect:

  1. Upper respiratory tract infections affect the sinuses and throat.
  2. Lower respiratory tract infections affect the airways and lungs.

(NHS 2018)

Lower RTIs are generally longer-lasting and more serious (NHS 2018).

RTIs are associated with numerous pathogens (including viruses, bacteria and fungi) (Bhuyan et al. 2017).

rti diagram
Upper RTIs affect the sinuses and throat, while lower RTIs affect the airways and lungs.

How do RTIs Spread?

RTIs are generally spread through direct contact, airborne particles or droplets (coughs and sneezes) from an infected person (Harvard Medical School 2017).

Refer to Infectious Diseases to learn more about the modes of infection transmission and how to prevent the spread of infectious diseases.

Common Respiratory Tract Infections

Below is an overview of some common RTIs. Please note this is not an exhaustive list.

Common cold

Type: Upper RTI.

Cause: Virus

Common symptoms:

  • Sore throat;
  • Runny nose;
  • Sneezing;
  • Cough; and
  • Headache.

Treatment: No specific treatment.

The common cold is the most prevalent contagious disease in Australia and can be caused by over 200 different viruses. Most of these viruses belong to the rhinovirus or coronavirus families.

Colds can affect the ears, nose and throat. They are generally not considered serious and will usually resolve on their own. However, they may lead to secondary infections in some cases, particularly in children.

Further information:

(Lung Foundation Australia 2016; Healthdirect 2018; Healthy WA n.d.)


Type: Upper or lower RTI.

Cause: Virus

Common symptoms:

  • Sore throat;
  • Fever;
  • Cough;
  • Body aches;
  • Fatigue; and
  • Gastrointestinal symptoms (more common in children).

Treatment: Preventative vaccination.

Influenza (the flu) is similar to the common cold but is generally more severe with a very sudden onset. In some cases, it can lead to life-threatening complications.

Those who are at an increased risk of serious complications include older adults over 65, children under 2, pregnant women and people who are immunocompromised.

(QLD Health 2020; NHS 2019; CDC 2018)


Type: Lower RTI.

Cause: Virus, bacteria or fungi.

Common symptoms:

  • Chest pain;
  • Cough;
  • Fever;
  • Fatigue;
  • Difficulty breathing; and
  • Loss of appetite.

Treatment: Usually treated with antibiotics. Severe cases may require hospitalisation.

Pneumonia is an infection causing inflammation of alveoli in one or both lungs. The alveoli (air sacs) in the lungs fill with secretions and fluid, decreasing the ability for oxygen to be transported across the tissue to adequately oxygenate vital organs. Patients may experience shortness of breath, hypoxia and often need oxygen therapy and ventilatory support.

Pneumonia can be a serious and potentially fatal infection, with young children, older adults and those with pre-existing health conditions most at risk of complications such as pleurisy, lung abscess or sepsis.

According to WHO (2019), it accounts for 15% of deaths of children aged under five. In 2017, it contributed to the deaths of 808 694 children.

As the immune system naturally weakens over time, older adults become more at risk of developing pneumonia as they age.

Pneumonia may present as a relapse after a cold or flu.

Further information:

(WHO 2019; NHS 2019; Lung Foundation Australia n.d; Gamache 2019)

rti pneumonia
Pneumonia causes the alveoli in the lungs to fill with pus and fluid, limiting oxygen intake and causing breathing to be painful and difficult.


Type: Upper RTI.

Cause: Bacteria or virus.

Common symptoms:

  • Pain, swelling and tenderness around cheeks, eyes and forehead;
  • Blocked nose;
  • Loss of smell or taste;
  • Thick, green or yellow mucus;
  • Headache;
  • Fever; and
  • Bad breath.

Treatment: Decongestant nasal spray or drops, and salt water sprays or solutions.

Sinusitis is an inflammation of the nasal sinuses. It generally presents as a secondary infection after a cold or untreated allergies.

Sinusitis generally resolves on its own after a few weeks.

(ASCIA 2019; NHS 2017)


Type: Lower RTI.

Cause: Virus or bacteria.

Common symptoms:

  • Cough (dry or productive);
  • Sore throat;
  • Headache;
  • Runny or blocked nose;
  • Aches and pains; and
  • Fatigue.

Treatment: No specific treatment.

Bronchitis is an infection of the bronchi (the main airways of the lungs that branch off the trachea), which causes them to become inflamed and create more copious amounts of secretions than usual. This results in a productive cough, which is an attempt to excrete sputum.

Bronchitis is usually caused by the same viruses that cause colds and influenza.

(Healthdirect 2017; NHS 2019)


Type: Lower RTI.

Cause: Virus

Common symptoms:

  • Dry cough;
  • Slight fever;
  • Runny nose;
  • Difficulty breathing; and
  • Noisy breathing (e.g. wheezing).

Treatment: No specific treatment.

Bronchiolitis causes inflammation and congestion in the smallest airways (bronchioles). It is usually caused by the virus RSV (respiratory syncytial virus) and almost exclusively affects infants under the age of two.

The symptoms are initially similar to those of a cold, but will then develop into coughing and in some cases, difficulty breathing.

Bronchiolitis is generally mild, clearing within 2 to 3 weeks.

(Mayo Clinic 2020; NHS 2018)

Further information:


Type: Upper RTI.

Cause: Virus or bacteria.

Common symptoms:

  • Sore throat;
  • Red, swollen and painful tonsils;
  • Difficulty swallowing;
  • Fever;
  • Headache;
  • Swollen lymph nodes;
  • Cough; and
  • Gastrointestinal symptoms (in younger children).


  • No specific treatment (viral).
  • Antibiotics (bacterial).

Tonsillitis is an inflammation of the tonsils, most common in children (though anyone can contract it). Sometimes it will cause small, white patches of pus on the tonsils or back of the throat.

Tonsillitis generally resolves on its own after a few days. Those who experience frequent bouts of tonsillitis may choose to undergo tonsillectomy surgery to remove their tonsils permanently.

(Healthdirect 2019; NHS 2017)

rti tonsilitis
Tonsilitis may cause small, white patches of pus on the tonsils or back of the throat.


Type: Upper RTI.

Cause: Virus, bacteria (rarely) or non-infection-related vocal strain.

Common symptoms:

  • Hoarse voice or voice loss;
  • Sore throat; and
  • Dry cough.

Treatment: No specific treatment.

Laryngitis is an inflammation and irritation of the larynx (voice box), causing swelling of the vocal cords and a consequent distortion of the voice.

It is usually caused by a virus, but in some cases it can be acquired through vocal strain without any infectious agent involved.

Acute laryngitis should resolve on its own in up to two weeks.

(Mayo Clinic 2018; NHS 2017)

Additional Resources


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Which of the following RTIs may be caused by fungi?

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