Human Parainfluenza Viruses (HPIV)

ABOUT

Human Parainfluenza Viruses (HPIVs) are common respiratory viruses that usually cause mild, cold-like symptoms. HPIVs are associated with croup in young children. Some people, such as children and adults with weakened immune systems, may be more likely to develop severe illness. Washing hands, not touching your face, and not being in close contact with people who are sick can help prevent infection. Most people with HPIVs will recover on their own.

There are four types of HPIVs and two subtypes that circulate at different times of the year. The incubation period, the time from getting infected with HPIV to symptom onset, is generally 2 to 6 days.

  1. HPIV-1 infections often cause croup in children. They can cause upper and lower respiratory illness and cold-like symptoms. There are usually more cases in the fall.
  2. HPIV-2 infections can also cause croup in children. They can cause upper and lower respiratory illness and cold-like symptoms. HPIV-2 infections are more common in the fall. They are less frequently detected than HPIV-1 and HPIV-3.
  3. HPIV-3 infections are more often associated with bronchiolitis and pneumonia. They usually occur in spring and early summer months. However, HPIV-3 infections can occur throughout the year, particularly when HPIV-1 and HPIV-2 are not in season.
  4. HPIV-4 (subtypes 4a and 4b) infections are diagnosed less often because of infrequent testing. They may cause mild to severe respiratory tract illness, including bronchiolitis and pneumonia. Seasonal patterns are not as well characterized but seem to occur in fall and winter each year.

All HPIVs can worsen chronic lung conditions, such as asthma.

SYMPTOMS

Symptoms generally appear 2 to 6 days after infection. Symptoms are like the common cold and can include: fever, runny nose, cough, sneezing, and sore throat. Other symptoms of HPIV illness may include ear pain, irritability, and decreased appetite.

Serious illness in children

HPIVs can also cause more serious illness in children, including:

  • croup (infection of the vocal cords [larynx], windpipe [trachea], and sometimes into the larger airways into the lungs [bronchi])
  • bronchitis (infection of the main airways that connect the windpipe to the lungs)
  • bronchiolitis (infection in the smallest airways in the lungs)
  • pneumonia (infection of the lungs)
  • worsening of underlying lung conditions, such as asthma

Symptoms of more serious illness in children may include:

  • barking cough
  • hoarseness
  • stridor (noisy or high-pitched sound with breathing)
  • wheezing

Illness in Adults

HPIVs commonly cause upper respiratory infections in adults. More severe illness, such as bronchitis and pneumonia may occur, especially in older adults and people with weakened immune systems.

Symptoms in adults may include:

  • fever
  • runny nose
  • cough
  • sore throat

You can have multiple HPIV illnesses in your lifetime.

TRANSMISSION

HPIVs are usually spread by direct contact with infectious droplets or by spread of droplets when an infected person breathes, coughs, or sneezes. HPIVs may remain infectious in expelled 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. HPIVs usually spread from an infected person to others through the air by coughing and sneezing, close personal contact, such as touching or shaking hands, touching objects or surfaces that have HPIVs on them and then touching your mouth, nose, or eyes. People can get HPIV infections any time of year.

TREATMENT/PREVENTION

Antibiotics are not effective against treating HPIVs. Antibiotics are only effective against bacterial infections. For information about safe antibiotic use, see CDC's Antibiotic Prescribing and Use. There is no vaccine or treatment that can prevent HPIV infection. To prevent the spread of HPIV, follow core prevention strategies for respiratory viruses:

  • Practice good hygiene (practices that improve cleanliness).
    • Cover your mouth and nose with a tissue when you cough or sneeze. If you don't have a tissue, cough or sneeze into your elbow, not your hands.
    • Learn and use proper handwashing techniques. Frequent handwashing is especially important in childcare settings and healthcare facilities.
    • Clean frequently touched surfaces regularly, such as countertops, handrails, and doorknobs.
  • Take steps for cleaner air.
  • When you have symptoms of a respiratory virus, take steps to prevent spread.

HEALTH CARE PROFESSIONALS

In hospital settings, healthcare providers should follow contact precautions, such as handwashing and wearing protective gowns and gloves. For more information, see CDC's 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings.

COMMUNITY

If you are sick with a common cold illness or cough that may be caused by HPIV, you can help protect others by staying home while you are sick, avoiding close contact with others, covering your mouth and nose when you cough or sneeze, keeping objects and surfaces clean and disinfected, and considering wearing a well-fitted mask; children ages 2 years and older can wear masks or respirators to protect themselves and others from HPIVs

LOCAL HEALTH DEPARTMENTS