Human parainfluenza viruses

Content

Introduction

Introduction

Human parainfluenza viruses (HPIV, from the English Human Para Influenza Viruses) include different types of viruses, belonging to the family of paramixoviruses, which infect the respiratory system, causing in most cases acute inflammation of the larynx, trachea and bronchi (acute laryngeal-tracheo-bronchitis); they can rarely cause pneumonia.

The disorders (symptoms) are very similar to those of the flu, from which the HPIV infection is not easily distinguishable and range from the common cold, to flu-like disorders (symptoms) (fever, body aches, cough, cold) to pneumonia. The symptoms (symptoms) usually develop 2 to 7 days after contracting the infection.

Transmission of HPIV occurs through direct inhalation of infected respiratory droplets or from the hands, through the eyes and nose.

Diagnosis is clinical and treatment is supportive. HPIV infection mainly affects infants, children, the elderly, and people with conditions that weaken the immune system (tumors, immunosuppressive therapies, bone marrow transplantation), although anyone can become infected. Over the course of a lifetime you can be repeatedly infected with HPIV.

Symptoms

Symptoms

The disorders (symptoms) caused by human parainfluenza virus (HPIV) infections are varied and also change based on the type of HIPV involved.

If the infection affects the mucous membranes of the nose and throat you can have:

  • fever
  • cold
  • cough
  • sore throat
  • hoarse voice for inflammation of the vocal cords

If the infection affects the trachea, bronchi and lungs, the complaints are more serious and can include:

  • high fever
  • pneumonia (lung infection)
  • bronchitis (bronchial infection)
  • bronchiolitis (inflammation of the small airways of the lungs)

Other disorders (symptoms) of parainfluenza syndromes caused by HPIV can include:

  • ear pain
  • irritability
  • decreased appetite
  • difficulty in breathing (dyspnea)

Acute laryngotracheobronchitis (infection of the larynx, trachea and bronchi) is the most common complaint, and begins as a common cold. Then there is fever, "barking" cough, hoarseness, and stridor (breathing noise due to narrowing of the airways), there may be lowered or hoarse voice due to inflammation of the vocal cords. The narrowing of the airways can cause difficulty in to breathe (respiratory failure, dyspnoea) which very rarely can worsen to the point of being fatal if not promptly treated.

Causes

Causes

Human parainfluenza viruses (HPIVs) belong to the paramixovirus genus and can cause a parainfluenza syndrome that affects the respiratory system and manifests itself with disorders (symptoms) of varying degrees.

There are 4 types of HPIV and two subtypes, which circulate at different times of the year.

  • HPIV-1 infections, they are the most frequent and occur mainly in autumn
  • HPIV-2 infections, they are less frequent than those of HPIV-1 and HPIV-3 and these also occur mainly in the fall
  • HPIV-3 infections, occur mainly in spring and early summer, although they can also occur at other times of the year, especially when HPIV-1 and HPIV-2 are not circulating
  • HPIV-4 infections (subtypes 4a and 4b), are the rarest and the seasonality is unknown

Infections with HPIV-1 and HPIV-2 are the leading cause of acute laryngotracheobronchitis in children, a respiratory disease that manifests itself as inflammation and swelling of the larynx, trachea and bronchi and can also affect the vocal cords. Both viral strains can cause severe flu-like symptoms (symptoms), such as pneumonia and bronchopneumonia.

HPIV-3 infections are highly contagious, affect a high percentage of babies in the first year of life, and can cause pneumonia and bronchiolitis (inflammation of the small airways in the lungs) in infants.

Finally, HPIV-4 infections are rarer than the other types and can cause respiratory diseases with various symptoms (symptoms) ranging from mild to severe.

The four types of HPIV can infect anyone repeatedly throughout a lifetime, although they particularly affect children, the elderly, and those with weak immune systems. Parainfluenza viruses (HPIVs) are responsible for 30-40% of all acute respiratory tract infections in infants and children, who usually become infected before the age of 5. Transmission of HPIV occurs through direct inhalation of mucus droplets containing the virus, emitted by an infected person with sneezing and coughing, or by touching surfaces contaminated by the droplets and putting their hands to their mouth, nose, or eyes. The low temperature and high humidity, typical of the autumn-winter-spring period, increase the survival of HPIV on skin, clothing and other objects, making it easier to spread, especially in schools, kindergartens, hospitals and other collective structures. The symptoms (symptoms) usually develop 2 to 7 days after contracting the infection.

Diagnosis

Diagnosis

The diagnosis is often made considering the disorders (symptoms), tests for confirming the infection (microbiological, which highlight the virus, or molecular, which identify viral antigens or the genetic material of the virus) are reserved for severe cases (severe pneumonia, respiratory failure) If the virus is suspected to have caused the lower respiratory tract infection, chest x-rays can be used, which confirms pneumonia or bronchopneumonia.

Therapy

Therapy

There is currently no specific treatment for parainfluenza virus (HPIV) infection.

Infections due to human parainfluenza viruses (HPIVs) are usually mild and short-lived, and usually resolve on their own within a few days. Treatment involves rest and the use of drugs to control fever and relieve symptoms (cough, sore throat, cold). Among the most used drugs are cough syrups, antipyretics to lower fever and pain relievers for sore. headache and muscle / joint pain. Antibiotics are not used against viral infections, so they should not be used unless prescribed by your doctor or pediatrician. If the complaints persist for more than a few days, or worsen (fever difficulty in breathing, severe pain) you should immediately notify your doctor or pediatrician.

Prevention

Prevention

There are currently no vaccines available to prevent parainfluenza virus (HPIV) infection, although vaccines against HPIV-1 and HPIV-3 are being studied. To reduce the risk of HPIV infection, as well as other respiratory viral infections, it is necessary to follow some general hygiene practices and small important precautions:

  • wash your hands often with soap or alcoholic gel
  • avoid touching your eyes, nose and mouth
  • avoid close contacts with sick people
  • ventilate the rooms
  • avoid too crowded places, where the risk of contagion is higher

If you are sick with parainfluenza syndromes, you should avoid infecting other people:

  • staying at home until complete recovery
  • avoiding close contact with others
  • covering the mouth and nose with a tissue o with the elbow when sneezing or coughing, and not with the hands which are one of the main vehicles for the spread of the virus
  • often cleaning objects and surfaces more contact (doorknobs, telephones)
Bibliography

Bibliography

Branche AR, Falsey AR. Parainfluenza Virus Infection Seminars in Respiratory and Critical Care Medicine.2016;37:538–554

Further links

Further links

EpiCentro (ISS). Parainfluenza syndromes

Centers for Disease Control and Prevention (CDC). Human Parainfluenza Viruses (HPIVs) (English)

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