About This Disease

There are four types of human parainfluenza viruses (HPIVs): HPIV-1, HPIV-2, HPIV-3, and HPIV-4. Parainfluenza viruses cause non-serious respiratory disease. Illness usually occurs in infants and small children, but anyone can become ill once infected. Like most respiratory viruses, symptoms range from fever, cough, sore throat, sneezing, wheezing, ear pain, anorexia, and irritability to severe lower respiratory illness that could include an infection/inflammation of the larynx, trachea, and bronchial tubes, bronchitis, bronchiolitis, or pneumonia. HPIV-1 and -2 are most commonly associated with cold-like symptoms in young children. HPIV-3 is often associated with pneumonia. HPIV-4, detected less often, usually causes mild to severe illness. Young children, the elderly, and those with weakened immune systems are at risk of severe disease. Transmission occurs from person-to-person by either close contact with an infected individual, coughs or sneezes from an infected individual, or touching surfaces contaminated with the virus. The best way to protect yourself is to wash your hands with soap and water, cover your mouth and nose when sneezing or coughing, avoid touching your face with unwashed hands, and avoid close contact with sick individuals. There is no treatment for HPIVs. There currently is no routine surveillance for HPIVs in Hawaii. Learn more about non-influenza respiratory viruses.


Signs and Symptoms

Parainfluenza viruses can cause upper and lower respiratory infections. In the case of upper respiratory illness, symptoms include fever, runny nose, and a cough/sore throat. For cases with lower respiratory infections, symptoms include croup, bronchitis, bronchiolitis, and pneumonia. Children, the elderly, and those with weakened immune systems are more likely to develop lower respiratory infections. Other symptoms of parainfluenza infection can include sneezing, wheezing, ear pain, irritability, and anorexia.


Parainfluenza viruses (HPIVs) are spread from person-to-person contact that could involve close personal contact, the air that an infected individual has coughed or sneezed in, or touching an object or surface contaminated with HPIVs and then proceeding to touch one’s mouth, nose, or eyes. HPIVs can remain in the air for over an hour and on surfaces for several hours and could cause infection in humans.


Testing is not usually performed for respiratory viruses because treatment would not change. Most physicians would make a diagnosis based on the signs and symptoms of an upper or lower respiratory infection. Laboratory diagnosis can be performed at Hawaii’s major clinical laboratories, if necessary.


There is currently no antiviral treatment for parainfluenza virus infection, much like the other non-influenza respiratory viruses.


There is no immunity to parainfluenza viruses. Currently, researchers are working on developing a vaccine.

Risk in Hawaii

Because there is no routine surveillance conducted on parainfluenza, seasonal trends are unknown. Anyone can get infected from parainfluenza viruses.


The best way to prevent any respiratory infection is to avoid close contact with sick individuals, proper hand hygiene, and avoid touching your face (especially mouth, nose, and eyes). The best way a sick individual can prevent further spread is to stay home from school or work, cover their nose and mouth when sneezing and coughing, and proper hand hygiene.

Additional Resources

Information for Clinicians

Human parainfluenza viruses most commonly cause upper and lower respiratory illness. The illnesses can range from the common cold to pneumonia, croup, and bronchitis. Severity of illness can depend on the virus type and whether the infection occurred in a young child, elderly individual, or someone with a weakened immune system. Laboratory diagnosis can be made by polymerase chain reaction assay, direct detection of viral antigens, using immunofluorescence or enzyme immunoassay, isolation in cell culture; or IgG antibody testing. There are no available antivirals for treatment of parainfluenza infection. Since most illnesses are mild, treatment of symptoms may be appropriate. There also is no vaccine to prevent illness, but researchers are working on developing one. To prevent outbreaks in healthcare settings, follow droplet and standard infection control precautions.

For more information: Centers for Disease Control and Prevention (CDC)