What is Parainfluenza?

Parainfluenza is a virus that affects the upper and lower respiratory systems in humans. It can manifest as a common cold or lead to a more serious illness, such as pneumonia. The four types of human parainfluenza viruses (HPIVs) cause different symptoms. They are easily spread through respiratory secretions and occur most often in children under the age of 5. Recurring infections are common though usually less severe.

An HPIV infection occurs when the virus enters the body through the mouth, nose or eyes after being picked up from a contaminated surface. Infected droplets released into the air during sneezing or coughing fits also contribute to the spread of this illness. The virus can remain active in the air for up to an hour and on surfaces for a few hours.

Symptoms vary depending on which type of HPIV is causing the infection. HPIV-1 and HPIV-2 usually lead to signs of croup, such as a barking cough. HPIV-3 often causes symptoms of lower respiratory illnesses such as bronchiolitis and pneumonia. Other signs of parainfluenza include a runny nose, sore throat, fever and irritability.

A diagnosis of HPIV can be done through nasal swabs, blood work and chest X-rays. Many cases of parainfluenza in which the only symptoms experienced are those of a common cold are thought to go undetected because the symptoms are so mild. Diagnoses are usually made in more severe cases.

Treatment for HPIVs depends on how serious the illness is and how young the patient is. It is a viral infection, so antibiotics are not prescribed. In mild cases, the symptoms can be treated with bed rest, a humidifier and over-the-counter pain medication to help reduce fevers.

HPIV-1 and HPIV-2 outbreaks typically occur in the fall of odd-numbered years, although HPIV-2 sometimes shows up annually. HPIV-3 outbreaks usually happen in the spring and early summer of every year. HPIV-4 outbreaks are rare.

Those most at risk of complications from parainfluenza include infants and children under age 2, the elderly, and people with compromised immune systems. Pediatricians recommend calling or bringing children in for a visit when they exhibit symptoms of croup or have a deep, congested cough. Some cases of HPIV require hospitalization if a life-threatening complication occurs.

No vaccine for parainfluenza is available as of 2010. The virus can be prevented by frequently washing hands and avoiding contact with those who have the illness. Kids who are sick should be kept home from school or daycare.