Human parainfluenza virus is a common virus that causes a number of infections, inlcuding the common cold, in infants and children, as well as in those with compromised immune systems. The virus is transmitted from person to person by exposure to droplets, either in a cough or a sneeze, or by droplets on objects like tables, countertops or medical equipment. The incubation period for the virus is between two to six days.
Respiratory symptoms
Parainfluenza is the leading cause of croup in children. Croup is an infection of the upper airway that causes significant swelling. Children with croup caused by parainfluenza exhibit a barking cough, difficulty breathing, rapid breathing and a feeling that their airway will close. Patients with croup also have stridor, which is a choking noise made as they inhale. Because they have difficulty breathing and swelling in the upper airway, children with croup can get dehydrated, leading to decreased urine output, dry lips, rapid heart rate and sunken eyes. Steroids and humidified air are helpful in patients with croup.
Parainfluenza also causes bronchiolitis, a condition of inflammation of the lower airways of the lungs. Patients with bronchiolitis exhibit rapid breathing and wheezing and a high-pitched noise as they exhale that is the result of air flowing through narrowed airways. Patients also demonstrate a coarse cough and respiratory distress with retractions of the chest muscles. Bronchiolitis runs its course without treatment, but some patients may need hydration, oxygen and inhalation therapy with bronchodilators.
Neurological symptoms
Parainfluenza can cause encephalitis, an inflammation of the brain. Patients with encephalitis exhibit fever, changes in their mental status, seizure, headaches and photophobia (an aversion to bright light). Parainfluenza can also cause meningitis, an inflammation of the tissues surrounding the brain and the central nervous system. Patients with meningitis have symptoms that are similar to those of patients with encephalitis. They also experience stiffness of the neck. It is important to rule out bacterial causes for these symptoms, because bacterial infections can be treated with antibiotics. Supportive care, such as hydration, should also be provided. There are no medicines that directly target parainfluenza.
Parotitis
In rare cases, parainfluenza can cause parotitis, an inflammation of the parotid glands, which are the main salivary glands in the face. Patients with parotitis have difficulty fully opening their mouths, pain when chewing or swallowing, dry mouth, fever and redness and swelling of the affected gland. Some patients with parotitis report abnormalities in their taste perception.
Patient with parotitis need fluid support to avoid dehydration. Otherwise, patients eventually improve without treatment.
References
- Centers for Disease Control and Prevention
- Red Book: Report of the Committee on Infectious Diseases; American Academy of Pediatrics; 2009
