Parainfluenza: Symptoms, diagnosis & treatment

Overview

Parainfluenza is a common respiratory virus that affects people of all ages, but it often targets young children, the elderly, and those with weakened immune systems. Despite the similar name, it is not the same as influenza (the flu) and causes different symptoms and risks, especially for children. In Australia, human parainfluenza virus (HPIV) infections occur throughout the year, with a peak in spring. Children under two years old are most frequently affected, with approximately 0.42 episodes per child per year¹. Although anyone can catch it, young children are particularly at risk of complications such as croup and bronchiolitis.

What is parainfluenza?

Parainfluenza is a viral infection caused by four viruses belonging to the paramyxovirus family. Each virus produces different signs and diseases. These viruses primarily affect the respiratory system, leading to illnesses such as the common cold, croup, laryngitis, pneumonia, and bronchiolitis. While young children are often most affected, adults can also catch parainfluenza.

Symptoms of parainfluenza

Parainfluenza viruses primarily target the nose, throat, and lungs. Symptoms can vary depending on the severity of the infection, age and health condition of the affected individual. Common symptoms include:

• Cough (can be dry or barking, particularly in children)
• Runny or stuffy nose
• Sore throat 
• Fever
• Hoarse voice
• Breathing difficulties
• Nasal congestion

In young children, parainfluenza often leads to croup, a condition marked by a barking cough and noisy breathing.

Types of parainfluenza viruses

There are four types of parainfluenza viruses (HPIVs). They all cause a respiratory infection, but the type, symptoms and location of the infection are determined by the type of virus involved. Here’s a breakdown of each type:

HPIV-1 and 2 (Human Parainfluenza Virus Type 1 and 2):

• It mainly causes colds and croup, which are characterised by a barking cough, stridor (high-pitched wheezing), and breathing difficulties, especially in young children.

HPIV- 3 and 4 (Human Parainfluenza Virus Type 3 and 4):

• A major cause of bronchiolitis and pneumonia, especially in infants and young children, whereas HPIV-4 is less common and usually associated with mild respiratory symptoms.

How is parainfluenza diagnosed?

Doctors usually diagnose parainfluenza through symptom evaluation and a clinical examination. In some cases, a nasal or throat swab is used to confirm the infection, especially when symptoms are severe or unclear.

Quick summary:

• Most cases are identified from symptoms.
• Nose or throat swabs may be done in hospitals or for high-risk patients.
• Blood tests are generally not required.

If you’re unwell, you can see your GP in person or arrange a telehealth session (if eligible under Medicare) for diagnosis and advice.

Treatment option

Parainfluenza has no specific antiviral treatment. Most people recover at home with adequate rest and care.

Home care tips

• Drink plenty of fluids to maintain hydration.
• Certain medication can be used to manage fever and aches.
• Take rest in a cool, calm environment.
• Use a humidifier or sit in a warm, steamy bathroom to ease a barking cough (especially helpful for croup).

Hospitalisation may be necessary for children or adults with breathing difficulties.

Quick summary:

• There’s no cure, but symptoms can be managed at home.
• Get urgent medical help for breathing difficulties or dehydration.
• Children with croup may require professional medical care.

Parainfluenza in adult's vs children

• In children, parainfluenza commonly causes croup, bronchiolitis, or pneumonia, especially under the age of five.
• In adults, symptoms usually resemble a cold or mild flu. Elderly individuals or those with chronic respiratory conditions (such as asthma or COPD) may develop more serious complications.

Important: Adults can contract parainfluenza from children, and children can catch it from adults; it is infectious.

Parainfluenza in Australia:  What you should know

In Australia, parainfluenza is a common cause of respiratory infections in young children, particularly under the age of two. It is a major viral trigger of croup, a condition marked by a barking cough and loud breathing. While infections occur throughout the year, distinct seasonal surges are well recognised. Research² from the Australian Capital Territory showed a marked rise in croup-related emergency visits during autumn compared to summer, with bronchiolitis and other respiratory illnesses peaking in winter. Another New South Wales study³ confirmed that croup cases increased in colder months, with strong links between lower temperatures and emergency visits. Parainfluenza is not a notifiable disease in Australia, so nationwide data is limited, and seasonal spikes may differ depending on the region and year. It’s often mistaken for flu or RSV (Respiratory Syncytial Virus), but it has distinct patterns and usually impacts younger children more seriously.

How is parainfluenza different from RSV and flu?

Parainfluenza, influenza (the flu) and RSV (Respiratory Syncytial Virus) are all respiratory viruses, but they act in different ways.

Virus	Common in	Key symptoms	Vaccine available
Parainfluenza	Children and adults	Barking cough, croup, fever	No vaccine
RSV	Babies and the elderly	Wheezing, bronchiolitis	For high-risk babies
Influenza	All ages	Fever, fatigue, muscle aches	Annual flu shot

Who is most at risk?

While parainfluenza can affect anyone, certain groups are more vulnerable to serious complications:

• Children under 5 (especially under 2)
• Adults over 65
• People with asthma, COPD, or other chronic respiratory diseases
• Individuals with weakened immune systems
• Babies born prematurely

Can parainfluenza come back?

Yes, parainfluenza can come back, and people can get infected more than once. There are four major types of parainfluenzas (HPIV-1 to HPIV-4), and an infection with one does not provide lasting protection against the others. Even with the same type, immunity tends to be temporary, making reinfections likely. Young children are especially affected since their immune systems are still developing. Many children are exposed to more than one HPIV strain before they start school. While repeat infections are usually milder, they can still trigger croup, bronchiolitis, or lower respiratory problems in vulnerable kids. Adults can also be affected, usually with mild, cold-like symptoms, though people with asthma, COPD, or weakened immune systems may develop more serious illness.

When to see a doctor?

You should see your GP in Australia or speak to a telehealth doctor if:

• Breathing becomes difficult or is too noisy.
• Symptoms don’t improve despite home care.
• A child has a persistent barking cough.
• You notice signs of dehydration.

You can also request a medical certificate for parainfluenza online through eligible telehealth services in Australia.

How Hola telehealth can help

Yes, Hola health consultation offers a convenient means to handle parainfluenza symptoms, particularly for mild infections. Hola Health's telehealth platform allows for easy access to healthcare from home. Our offerings consist of:

• Telehealth consultations: Patients can speak with qualified doctors online to address symptoms such as cough, fever, or respiratory issues. The doctor will evaluate the condition and suggest a treatment plan, if needed.
• Prescriptions online: If an online doctor deems it necessary, they may issue online prescriptions which are sent through an SMS. The prescriptions can be dispensed at a local pharmacy or delivered on the same day through online pharmacy delivery.
• Referrals : Should additional evaluation be required, online doctors can refer patients for diagnostic tests or to a specialist for further assistance.
• Medical certificate for sick leave: For individuals needing time off, our service provides same-day and multi-day medical certificates for absences from work or school, if clinically appropriate.

Conclusion

In conclusion, parainfluenza is a widespread viral infection that affects the respiratory system, causing symptoms like fever, cough, and breathing difficulties. While there is no specific antiviral treatment, most cases can be managed through supportive care. Preventive measures, such as maintaining good hygiene and avoiding close contact with infected persons, can help limit the transmission of the virus, especially in high-risk groups such as young children and those with compromised immune systems.

FAQs

Is parainfluenza contagious in adults and children?

Yes. The virus spreads through coughing, sneezing, or touching contaminated surfaces.

How is parainfluenza different from the flu or RSV?

Parainfluenza is a common cause of croup and barking cough in children. Influenza, on the other hand, brings high fever and muscle aches. RSV mainly affects babies, causing wheezing or bronchiolitis.

How long should I stay home with parainfluenza?

You should stay home until your fever subsides and your health improves. Most individuals recover within a week.

Can adults get croup from parainfluenza?

Croup is uncommon in adults but can occur. Their symptoms are usually less severe, often limited to a dry cough or hoarseness.

Is there a vaccine for parainfluenza in Australia?

No, there is currently no vaccine for parainfluenza in Australia.

Can I get a medical certificate for parainfluenza online?

Yes. Australian telehealth services can provide medical certificates for parainfluenza if you’re unwell or unable to work or care for others.

How long does parainfluenza last in adults?

Most healthy adults recover in 5-7 days, although the cough can last longer.