Human parainfluenza viruses (HPIVs) are common respiratory viruses affecting people of all ages. Human parainfluenza virus 3 (HPIV-3) is a frequent cause of respiratory illness, particularly in infants and young children. While sharing some similar symptoms, HPIV-3 is distinct from influenza, commonly known as the flu.
Understanding Parainfluenza 3
There are four main types of HPIVs (HPIV-1, HPIV-2, HPIV-3, HPIV-4). HPIV-3 is a particularly prevalent type, often associated with more severe lower respiratory tract infections like pneumonia and bronchiolitis, especially in infants and young children.
The virus primarily spreads through respiratory droplets from coughing or sneezing. Direct contact with infectious secretions or contaminated surfaces can also transmit the virus. HPIV-3 infections can occur year-round, but typically peak in the spring and early summer.
Symptoms and Manifestations
Symptoms of HPIV-3 infection generally appear 2 to 7 days after exposure and can vary depending on a person’s age and immune status. Common upper respiratory symptoms resemble a cold and include fever, runny nose, cough, sneezing, and a sore throat. Other generalized symptoms may encompass ear pain, irritability, and decreased appetite.
HPIV-3 can also lead to more severe lower respiratory tract infections, particularly in infants, young children, and immunocompromised individuals. Bronchiolitis, an inflammation of the small airways in the lungs, is frequently associated with HPIV-3, especially in infants. Pneumonia, a lung infection, is another possible serious manifestation of HPIV-3.
While HPIV-1 and HPIV-2 are more commonly linked to croup, HPIV-3 can also cause this condition. Croup is characterized by a distinctive “barking” cough, hoarseness, and noisy breathing (stridor) due to swelling around the vocal cords and windpipe. The cough and other symptoms of croup are often worse at night. Infants, young children, older adults, and people with weakened immune systems are at higher risk for severe illness.
Diagnosis and Medical Management
Diagnosis of HPIV-3 infections often begins with a clinical assessment. Confirmation can be achieved through laboratory tests, such as polymerase chain reaction (PCR) performed on nasal swabs or other respiratory secretions.
There is no specific antiviral treatment for HPIV-3 infection in most cases. Instead, medical management focuses on supportive care to alleviate symptoms. This includes ensuring adequate hydration and reducing fever with over-the-counter medications like acetaminophen or ibuprofen. Using a cool mist humidifier can help with respiratory comfort, especially for symptoms like croup.
Monitoring for signs of worsening symptoms or respiratory distress is important, particularly in children. Hospitalization may be necessary for severe respiratory distress, dehydration, or persistent stridor. Antibiotics are not effective against HPIV-3 because it is a viral infection, but they may be prescribed if a secondary bacterial infection develops.
Prevention and Recovery
Preventing the spread of HPIV-3 involves practicing good hygiene. Frequent handwashing with soap and water for at least 20 seconds, especially after coughing or sneezing, is an effective measure. Avoiding touching the eyes, nose, and mouth, and cleaning and disinfecting frequently touched surfaces can help reduce transmission.
To prevent further spread, it is advisable to avoid close contact with sick individuals and to stay home when experiencing symptoms. Currently, there is no vaccine specifically approved for HPIV-3, although research is ongoing to develop vaccine candidates.
Most healthy individuals recover from HPIV-3 infection within a week to 10 days. A cough may linger for a longer period after other symptoms resolve. It is important for parents and caregivers to watch for signs that might indicate a need for further medical attention during recovery, such as persistent high fever, difficulty breathing, or a worsening cough.