Parainfluenza virus

• Parainfluenza virus is a virus that causes upper respiratory infection (including the common cold and bronchiolitis); most often in children, also called human parainfluenza virus.

Parainfluenza virus

Symptoms and signs

• Human parainfluenza viruses (HPIVs) commonly cause upper and lower respiratory illnesses in infants, young children, older adults, and people with weakened immune systems, but anyone can get infected. After you get infected, it takes about 2 to 7 days before you develop symptoms.

• Symptoms of upper respiratory illness may include

• fever
• runny nose
• cough
• Symptoms of lower respiratory illness may include

Phylogenic tree of the pneumoviridae & paramyxovirus families

• croup (infection of the vocal cords (larynx), windpipe (trachea) and bronchial tubes (bronchi))
• bronchitis (infection of the main air passages that connect the windpipe to the lungs)
• bronchiolitis (infection in the smallest air passages in the lungs)
• pneumonia (an infection of the lungs)
• Other symptoms of HPIV illness may include

• sore throat
• sneezing
• wheezing
• ear pain
• irritability
• decreased appetite
• If your symptoms are severe or do not improve, you should seek medical attention.

• You can have multiple HPIV illnesses in your lifetime.

• Different Types of HPIVs
• HPIV-1 and HPIV-2 both cause croup, with HPIV-1 most often identified as the cause in children. Both can also cause upper and lower respiratory illness, and cold-like symptoms.
• HPIV-3 is more often associated with bronchiolitis, bronchitis, and pneumonia.
• HPIV-4 is recognized less often but may cause mild to severe respiratory illnesses.

Fusion glycoprotein trimer

Reinfection

• People can get multiple HPIV infections in their lifetime.
• These reinfections usually cause mild upper respiratory tract illness with cold-like symptoms.
• Reinfections can cause serious lower respiratory tract illness, such as pneumonia, bronchitis, and bronchiolitis in some people. Older adults and people with compromised immune systems have a higher risk for severe infections.
• Most children 5 years of age and older have antibodies against HPIV-3 and approximately 75% have antibodies against HPIV-1 and HPIV-2.

Transmission

• HPIVs usually spread by direct contact with infectious droplets or by airborne spread when an infected person breathes, coughs, or sneezes.
• HPIVs may remain infectious in airborne droplets for over an hour and on surfaces for a few hours depending on environmental conditions.
• People are most contagious during the early stage of illness.
• People usually get HPIV infection in the spring, summer, and fall. However, it is possible to get infected at any time of the year. For more information, see HPIV Seasons.

Prevention and Treatment

• Currently, there is no vaccine to prevent HPIV infection. However, researchers are trying to develop vaccines. Also, there is no specific antiviral treatment for HPIV illness. Most HPIV illnesses are mild and typically require only treatment of symptoms.
• In hospital settings, healthcare providers should follow contact precautions, such as handwashing and wearing protective gowns and gloves.

Parainfluenza virus Resources
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