Types of Human Parainfluenza Viruses: Symptoms, Prevention, and Treatment

If you are a parent or you work around children, you are well aware that there are many illnesses that spread like wildfire through both schools and homes, especially during flu season. One of the most common illnesses that affect younger children easily is human parainfluenza viruses. This is because this virus spreads very easily and there are many types of human parainfluenza viruses. While most people tend to get better without needing any treatment, but some types of the virus can cause severe disease in some people. Let’s learn about the different types of human parainfluenza viruses.

Human parainfluenza viruses (HPIVs) are a group of RNA viruses that belong to the Paramyxoviridae family. They are a common cause of respiratory infections in humans, especially in young children, elderly adults, and immunocompromised individuals. There are four different viruses in the group, with each one causing its own symptoms and illnesses. The four types of HPIVs all cause respiratory infections, and while some people tend to get better without needing any treatment, others can get severely infected by these viruses. HPIV infections are most common in children. The four types of human parainfluenza viruses include:^(1,2,3)

• HPIV-1
• HPIV-2
• HPIV-3
• HPIV-4

All types of HPIV cause an infection either in the lower or the upper respiratory tract of the body. An interesting fact is that the symptoms of human parainfluenza virus infections are usually very similar to those of the common cold. When the cases are mild, it leads to doctors often misdiagnose HPIV infections as being just a common cold.⁽⁴⁾

As mentioned earlier, most people who catch an HPIV infection usually recover without needing any treatment, though those who have a weakened immune system, have a significantly higher risk of developing complications or a life-threatening infection.⁽⁵⁾

Let us look at the four different types of human parainfluenza viruses.

There are four types of human parainfluenza viruses that exist and they all cause respiratory infection. The exact type of infection, location of the infection, and symptoms depend on the type of virus that you have. The four types of HPIV can occur in anybody. Let us take a closer look at these four types of human parainfluenza viruses.

1. HPIV-1

   Human parainfluenza virus type 1 is one of the most common causes of croup in children. Croup is a type of respiratory illness that is known for its characteristic barking cough. A child experiences coughing and difficulties in breathing due to swelling around the windpipe, voice box, and bronchial tubes. This happens because of the infection caused by the virus in the upper airway. Croup is usually caused by HPIV-1, but HPIV-2 can also sometimes cause croup, but it is rare.⁽⁶⁾

   HPIV-1 is transmitted when you come in contact with respiratory secretions from infected individuals, such as through coughing and sneezing. The virus can cause symptoms such as fever, cough, runny nose, sore throat, and sometimes, difficulty breathing.

   Most people recover from HPIV-1 infections within a week or two without needing any special treatment, although some may require supportive care, such as rest, fluids, and over-the-counter medications to manage the symptoms. In some rare cases, especially in those people who have a weakened immune system or underlying health conditions, HPIV-1 infections can lead to more severe illnesses, such as pneumonia.⁽⁷⁾

   Prevention of HPIV-1 infections is possible by following good hygiene practices, such as frequent hand washing, avoiding close contact with sick individuals, and covering your mouth and nose when coughing or sneezing. There is no vaccine available for HPIV-1 at present.⁽⁸⁾

2. HPIV-2

   HPIV-2 stands for human parainfluenza virus type 2, which is also a member of the Paramyxoviridae family of viruses. It is a common cause of respiratory infections, especially in young children. HPIV-2 is also known to cause cold and croup in children, but the problem is that doctors are able to detect this virus much less frequently as compared to HPIV-1. HPIV-2 is mostly seen infecting children in the fall months, but again the infection rate is to a lesser degree than that of HPIV-1.⁽⁹⁾

   Similar to HPIV-1, HPIV-2 is transmitted through contact with respiratory secretions from infected individuals, such as through coughing and sneezing. The virus can cause symptoms such as fever, cough, runny nose, sore throat, and sometimes, difficulty breathing.

   Most people tend to get better from HPIV-2 infections within a week or two without needing to take any specific treatment, although some people may need to supplement their care with extra rest, fluids, and over-the-counter medications to manage the cold and cough symptoms. In some rare cases of HPIV-2, especially in people with weakened immune systems or underlying health conditions, HPIV-2 infections can cause more severe illnesses, such as pneumonia.⁽¹⁰⁾

   Prevention of HPIV-2 infections is possible by following good hygiene practices, such as frequent hand washing, avoiding close contact with sick individuals, and covering your mouth and nose when coughing or sneezing. Just like HPIV-1, a vaccine for HPIV-2 is not available at present.

3. HPIV-3

   Human parainfluenza virus type 3, or HPIV-3, is commonly linked with bronchiolitis and pneumonia. While HPIV-3 is also known to generally affect young children, but it can also affect older adults. Bronchiolitis is a condition in which swelling occurs due to inflammation in the bronchioles, which are the smallest airways located in the lungs. HPIV-3 is known to cause infections typically in the spring and early summer seasons, though it can also affect someone at any other time of the year.⁽¹¹⁾

   HPIV-3 gets transmitted from one person to another when they come in contact with the respiratory secretions of an infected individual, such as through coughing and sneezing. The virus is known to cause respiratory-related symptoms like sore throat, difficulty breathing, runny nose, cough, along with fever. In some cases, especially in infants, HPIV-3 infections may cause conditions like bronchiolitis or pneumonia.

   Experts are not sure about what is the exact period of time that a person remains contagious after being infected with HPIV-3. However, studies have shown that viral shedding may continue to take place even after several months of having the infection even though a person may no longer be experiencing the symptoms. Due to this, the risk of passing on HPIV-3 infection to others remains active even after a few months of getting infected yourself.⁽¹²⁾

   Once infected, most people tend to recover from HPIV-3 infections within a week or two without needing any kind of special treatment. However, some people, especially older adults, may need supportive care, including fluids, over-the-counter cold, and cough medications, and rest to manage symptoms. In case of severe illness from HPIV-3 infection, severe cases, hospitalization may be required.⁽¹³⁾

   It is possible to prevent HPIV-3 infections by following good hygiene practices, including frequent hand washing, avoiding coming in close contact with those who are visibly sick, and covering your mouth and nose while coughing or sneezing. It is interesting to note that vaccines for HPIV-3 are currently being developed and tested. Currently, chimeric bovine-human parainfluenza virus types 3 vaccines are being tested to see their effectiveness in infants and young children.⁽¹⁴⁾

4. HPIV-4

   Human parainfluenza virus type 4 (HPIV-4) is one of the rarest types of the virus as compared to all three – HPIV-1, HPIV-2, and HPIV-3. Unlike the other types of HPIV, HPIV-4 does not seem to have a seasonal pattern of infection. It is also a far less common cause of respiratory infections than the other parainfluenza viruses and is usually known to cause mild illness only. Very less is still known about HPIV-4 and research is still going on to discover more about this type of human parainfluenza virus.^(15,16)

HPIV-1 and HPIV-2 are known to typically cause croup (a barking cough) along with symptoms that are similar to the common cold and flu. On the other hand, HPIV-3 and HPIV-4 are known to cause bronchiolitis and pneumonia. Some of the common symptoms for all four types of parainfluenza virus may include:⁽¹⁷⁾

• A rough or barking kind of cough, known as Croup
• Cough
• Fever
• Sore throat
• Stuffy nose
• Wheezing
• Hoarseness
• Vomiting
• Diarrhea
• Loss of appetite
• Redness in the eyes
• Shortness of breath or labored breathing
• Difficulty swallowing
• Ear pain

In most cases, the symptoms of the human parainfluenza virus are not so severe that they become a cause of concern or need treatment. However, in infants, older adults, or anyone who has a weakened or compromised immune system, HPIV infections may prove to be life-threatening and require immediate medical assistance. The same holds true for those who have recently had an organ transplant.⁽¹⁸⁾

If you are part of this high-risk group and you suspect that you might have contracted an HPIV infection, you should consult a doctor at the earliest, or head to your closest emergency room if you find the symptoms getting worse.

The human parainfluenza virus can also cause upper respiratory tract infections within the sinuses and throat. These can give rise to conditions like the common cold, sinus infection, sore throat, epiglottitis, and even laryngitis. Epiglottitis is a condition that affects the epiglottis, which is the thin flap present in the throat that prevents food and drinks from going into your windpipe. In epiglottitis, inflammation and swelling affect the epiglottis. Laryngitis, meanwhile, refers to the inflammation of your voice box, or the larynx.⁽¹⁹⁾ Epiglottitis may also give rise to symptoms like difficulty swallowing and a very sore throat, while laryngitis may cause your voice to become hoarse or you may even lose your voice. Sinus infections that may happen due to HPIV may cause symptoms like headaches, fatigue, congestion, and postnasal drip, a condition where you feel the mucus dripping into the back of the throat.

HPIV can also cause lower respiratory tract infections, which may also affect the lungs. Some of the common lower respiratory infections may include influenza, pneumonia, and bronchiolitis.

Human parainfluenza viruses are extremely contagious and they get transmitted when you come into contact with bodily secretions containing the body, including the fluids present in sneezes and runny noses. Sneezing is one of the most common ways in which this virus gets transmitted.

It is possible to contract parainfluenza in many ways as the human parainfluenza virus can survive for nearly ten hours on any porous surface.⁽²⁰⁾ So if you happen to touch a contaminated surface with your hands and then touch your hands to your mouth or nose, you may end up contracting the virus.

Of course, it is also possible to catch the virus by coming in close contact with another person who has HPIV. Contact includes being around them in an indoor area where they are sneezing or coughing, or touching them such as hugging or even kissing. A person is most infectious during the early stages of the infection.

After the initial transmission, it typically takes around two to seven days for the symptoms to start appearing. Even if you have had HPIV before, it is still possible to contract the infection once again.⁽²¹⁾

Most children end up catching the parainfluenza virus by the time they reach the age of five years. Some HPIV infections are also known to be more common in certain age groups and genders. For example:

• Boys tend to get more affected by croup, pneumonia, and bronchiolitis than girls.
• Bronchiolitis is more commonly detected in spring and winter.
• Bronchiolitis tends to usually occur in children who are in the age group of two to six months.
• Croup is most diagnosed in the fall and winter seasons.
• Children under the age of two are most at risk to develop pneumonia and bronchiolitis.
• Children between the ages of three months to five years old are most at risk of getting croup, with two-year-olds being at the highest risk.
• Nearly 10 to 15 percent of respiratory infections in children may result in pneumonia.

Pneumonia is most commonly diagnosed during the spring and winter months. The transmission of pneumonia increases manifold in crowded areas.

Your doctor will begin the diagnosing process with a full physical examination to determine if you have the symptoms of the human parainfluenza virus. In cases of children also, the same procedure is followed and your child’s doctor will first give your child a thorough physical exam to observe your child’s symptoms. Your doctor will also have knowledge about any local outbreaks of HPIV, which will help them get closer to diagnosing whether or not your child has a parainfluenza infection.

To get a more accurate diagnosis, your doctor may take a nasal or throat swab. Such swab tests can help detect and accurately identify if there is any virus present in the cell cultures. Your doctor may also use the results of the swab tests to detect the presence of any antigens that your body manufactured to fight off the virus. 

Your doctor may also prescribe certain imaging tests, including a CT scan or X-ray of your chest to get a look at your respiratory system. CT scans and X-rays will help your doctor understand the extent of your symptoms and whether you have developed any complications like pneumonia.

As mentioned above, many people recover on their own from a parainfluenza infection without needing any specific treatment. There is also no treatment that can get rid of the HPIV from the body. So if you have contracted the human parainfluenza virus, then you have to let it run its course, while doing certain things to help alleviate your symptoms. It is possible to treat most human parainfluenza viruses at home as most cases tend to be mild. It is important to remember that there is no point in self-treating yourself with antibiotics because this infection is caused by a virus, not bacteria. In most typical cases of HPIV, the treatment revolves around decreasing the severity of your symptoms until the virus runs out its course.^(22,23)

Some of the common treatments or therapies for relieving the symptoms of HPIV include:

• Drinking plenty of fluids.
• Taking Ibuprofen or acetaminophen to lower your fever and reduce overall discomfort.
• Using a cool-mist humidifier to loosen the mucus in the airway.
• Taking analgesics like aspirin.
• Taking a hot shower.

In cases of children, your child’s doctor may prescribe corticosteroids if your child has developed croup due to an HPIV. Corticosteroids are a class of anti-inflammatory drugs that come in handy since the cough and breathing difficulties caused by croup lead to swelling and inflammation in the upper airway. Corticosteroids help reduce this swelling and therefore, alleviate the coughing and breathing problems the child is facing.⁽²⁴⁾

Depending on the exact age of the child, and the severity of their symptoms, a doctor is likely to recommend certain cold or cough medications.

There are certain steps you can take to prevent parainfluenza, including following good hygiene steps such as washing your hands regularly, avoiding touching the eyes, mouth, or nose without washing or sanitizing your hands, and disinfecting surfaces that are common breeding places for viruses. You should also avoid coming in close contact with anyone who appears to have a viral infection, is coughing, or sneezing. At the same time, if you are sick, you should also stay at home and avoid spreading the infection to others. Remember that there is no vaccine for preventing human parainfluenza virus at present.

Human parainfluenza virus does not cause a serious illness in most people, though the symptoms tend to be quite uncomfortable and can last for several days. For most people who have a well-functioning immune system, it is possible to fight off the infection without needing any specific treatment.

It is possible for anyone to get an HPIV infection, with healthy people usually recovering without the need for treatment. However, in children, older adults, and people who have a compromised or weakened immune system, it can cause severe illness that needs immediate medical attention.

Anyone experiencing the symptoms of HPIV should stay at home and avoid transmitting the virus to others. If you develop severe symptoms or you are at a high risk of developing serious complications from HPIV, you must consult a doctor and seek medical assistance at the earliest.

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