Learn About Human Metapnuemovirus (hMPV)
Human Metapneumovirus (hMPV) is a respiratory virus that causes a basic upper respiratory infection (a cold) in patients. It usually occurs in the winter and early spring, along with the “flu” season. The virus was unknown until 2001 when it was first discovered, and, since that time, researchers are still trying to determine the virus’s impact and extend with causing disease.
- hMPV causes upper respiratory infections in all ages, but is most common in children, particularly under the age of 5.
- Symptoms include runny nose, nasal congestion, cough, sore throat, headache and fever. A very small number of individuals may get some shortness of breath. The symptoms are self limited, meaning they go away on their own with no treatment after a few days.
- A very small number of people are at risk for a more severe pneumonia, especially those over the age of 75, are taking steroids, or cancer/transplant medication for cancer or transplants (immunosuppressed).
What is hMPV?
hPMV is a virus that enters the body through contact with an infected individual. It enters through your mouth, eyes, and nose (mucus membranes). It has gained more recognition as a leading cause of acute respiratory disease (cold) in children since its discovery in 2001. Studies have shown that most children have shown prior infection with hMPV by age 5. A smaller number of children (5% to 16%) will develop a lower respiratory tract infection such as pneumonia. Infants, specifically 0-5 months, seem particularly susceptible.
This virus affects adults of all ages—usually a reinfection from being infected as a child. It has been shown to be a major factor for respiratory illness in the elderly (>65 years of age), causing disease in up to 10% of people tested.
How Does hMPV Affect Your Body?
Upon entering the body, hMPV infects the cells in your respiratory tract. The infection of these cells by the hPMV leads to the release of local chemicals and hormones that can cause the body’s immune response. This response causes the classic symptoms of a “cold”, including local pain, low grade fever, cough, runny nose, headache, and sore throat. In some individuals, the disease can spread to your main airways, or bronchi, leading to increased cough and wheezing. In children under the age of 1 year, decreased fever and weight loss is also seen.
How serious is hMPV?
In general, hMPV is not very serious. Most people have very few symptoms, which resolve on their own without treatment, usually within a few days. Patients with asthma may develop a subsequent asthma attack after infection, which commonly occurs with other respiratory viruses. The elderly and immunosuppressed are at an increased risk for developing pneumonia, which can be severe. However, hMPV appears less serious than other respiratory infections, including adenovirus and influenza. One study showed that only 2.8% of hospitalized patients with pneumonia had hMPV as the cause.
hMPV Symptoms, Causes, and Risk Factors
hPMV is a respiratory virus that can cause a primary and secondary infection. A primary infection is the first infection that occurs with an individual, and most people are infected by age 5. As an adult, you can have another infection, or secondary infection, and usually these infections are more mild and limited due to prior immunity, unless you are at risk as listed below.
Patients with hMPV usually have no symptoms (asymptomatic) or mild symptoms similar to a cold (an upper respiratory tract infection). These include:
- Runny nose
- Sore throat
Young children, the elderly, and those with a weakened immune system may develop a more severe illness with hMPV. These include:
- Difficulty breathing
- Asthma flare-up
- Poor feeding (children under 1 year)
For those individuals at increased risk for severe disease, more severe symptoms may include a high fever, shortness of breath, inability to walk due to shortness of breath, and complete fatigue. The cough may become severe and be associated with severe wheezing, including a persistent cough, that does not get better with inhaler use.
The cause of hMPV is a virus that is a spread to individuals when they come into contact with a sick individual with active infection (as listed above). You are not more likely to get infection if you have a history of asthma, COPD, emphysema, or any other lung disease. Likewise, immunosuppression, such as cancer or transplantation, does not increase your risk of getting an infection. However, once infected, you risk of severe disease might be altered by these other diseases.
The likelihood of getting infection from hMPV remains the same regardless of underlying diseases such as asthma, COPD, cancer, or transplantation. In addition, smoking does not appear to increase your likelihood of getting an infection. However, you are at risk of developing more severe disease, which would include pneumonia and wheezing consistent with an asthma exacerbation, if you have the following:
- Asthma using inhaled or oral steroids
- Child under year 1
- Adults over age 65
- Long term steroid use
There is no known associated risk with other lung diseases including pulmonary fibrosis or bronchiectasis. However, despite this lack of evidence, most doctors feel that an increase risk does exist for these individuals.
When to See Your Doctor
Most people with an upper respiratory track infection “cold” do not need to see a doctor. However, if you develop shortness of breath, severe cough, wheezing, or inability to feed or care for oneself, a doctor should be seen.
Diagnosis and Treatment
As with influenza and RSV, infection with hMPV can increase the risk for subsequent bacterial pneumonia, particularly with pneumococcus. Treatment is geared toward alleviating symptoms. In vitro and animal studies suggest ribavirin may be effective, however clinical studies are lacking.
Recent advances in the epidemiology clinical spectrum and diagnosis by RT-PCR of hMPV has improved the early recognition of this syndrome. Subsequently, a potential reduction in the use of inappropriate antibiotics and antivirals may be a result of this early recognition (Sumino, 2005 #177; Johnstone, 2008 #1). In addition, the recent recognition of hMPV as a nosocomial agent in long-term care facilities and reported outbreaks in schools further highlights the need for early diagnosis in order to stem the outbreak with infection control and public health measures.
What to Expect
Most physicians will diagnose patient with an upper respiratory infection or “cold” based on a collection of symptoms along with a particular time of year; usually the presence of a fever, runny nose, cough, and sore throat in the winter months is enough to make the diagnosis. With this diagnosis, physicians will routinely not search for the causative virus as this practice does not alter the treatment course. However, in some cases, testing is performed and on occasion, a patient may be diagnosed specifically with hMPV.
Mainly you will see your doctor in the office and the diagnosis of a “cold” or upper respiratory tract infection is made based on the symptoms you tell your doctor and the findings on examination. In most cases, the doctor will stop any further testing and treat the symptoms of your cold as listed below. In some cases, particularly at the height of the influenza season, your doctor will do testing to look for influenza. In this case, your testing will involve a nasal swab whereby the physician will insert a long swab into the back of your nose for a sample. In some cases the physician will use some saline (water) to spray and then collect the sample. Finally, in severe hospitalized cases, which are a minority of cases, you may undergo a bronchoscopy where a small, flexible camera is inserted into your lung and a sample of fluid is removed. This is only reserved for more severe cases, and the goal of this testing to detect influenza as treatment can be stopped (or started) based on the results.
How hPMV is Diagnosed
In some cases, your doctor may test you for influenza. This test involves swabbing the nasal (nose) passage by inserting a long swab into the back of your nose to collect a sample. In very few severe hospitalized cases, you may undergo a bronchoscopy where a small, flexible camera is inserted into your lung, and a sample of fluid is removed. This is only reserved for more severe cases, and the goal of this testing is to detect influenza as treatment can be stopped (or started) based on the results.
From the sample listed above, a DNA based test is performed. The swab (or fluid) is then tested against approximately 9 different viruses that cause respiratory infections. This testing is done in a laboratory and usually take 1-2 days for the results to return. In a research setting, diagnosis may include growing the virus on specialized tissue. However, in a clinical setting such as a hospital or clinic, DNA testing is performed and hMPV is part of a panel of respiratory virus testing.
How It’s Treated
There is no direct treatment for hMPV. Treatment is supportive, meaning the symptoms of the disease are treated rather than therapy directly against the virus. Mainly, the use of medication to control pain and fever (acetaminophen and ibuprofen) along with decongestants (pseudoephedrine) are used. If you have wheezing or cough, the use of an as-needed inhaler is recommended (eg, albuterol). Finally, patients with more severe wheezing may escalate their therapy for asthma, which may include higher doses of an inhaled corticosteroid or initiation of oral prednisone. One study in children under the age of 5 years showed that steroids were used only 12% of the time with additional oxygen only 3% of the time in cases of hPMV.
Living with hMPV
Since hMPV is a self limited disease, living with symptoms for a prolonged period of time is unlikely. In fact, persistent signs of an upper respiratory infection, or “cold”, should require additional study by a physician for alternative diagnoses. Otherwise, infection from hMPV will resolve within days without lasting symptoms.
What to Expect
Infection with hMPV usually causes symptoms of the common cold that last roughly 2-5 days. By day 2 of disease, most of patients will notice improvement, and many will feel completely fine by day 5. In patients with underlying asthma or other lung disease, symptoms may last a few days longer, but rarely more than 10 days. Any symptoms of a “cold” or upper respiratory tract infection lasting more than 14 days require an evaluation by a physician for an alternative diagnosis.
Managing the Disease
Since infection with hMPV is short, management occurs over the ensuing days and is limited. Treatment of fever and pain with over the counter medication is recommended in addition to decongestants such as pseudoephedrine. Management of chronic lung disease or asthma should only be altered for increased wheezing or symptoms of disease caused by hMPV infection and this management (and symptoms) will be short lived in general. Finally, precautions and protection from infection such as hMPV, influenza, and other contagious diseases should always be taken by patients with chronic lung diseases such as COPD, asthma, and pulmonary fibrosis. This protective process will provide protection against hMPV as well as influenza, adenovirus, and other respiratory infections. In addition, all patient should be up to date on vaccinations and primary heath-care treatment, such as a yearly physical examination.
The Lung Association recommends patients and caregivers join our Living with Lung Disease Support Community to connect with others facing this disease. You can also call the Lung Association’s Lung Helpline at 1-800-LUNGUSA to talk to a trained respiratory professional who can help answer your questions and connect you with additional support. Upper respiratory infections are self limited in scope, and thus long term support is largely not available.
Questions to Ask your doctor about hMPV
Many upper respiratory tract infections do not prompt specific questions to physicians, but a number or general questions for respiratory tract infection prevention can be applied generally to all individuals, particularly those with active lung disease, cancer, and/or transplantation.
- Am I at increased risk for getting a lung infection?
- If I get a lung infection, am I at increased risk for developing a severe pneumonia?
- Are there any lung infections that I should be concerned about given my health?
- Am I at risk of having a worse or longer “cold” than the average person
- What steps could I take to protect myself from getting a cold?
- How long should I wait after getting a cold before it is “too long” and thus I need to come in and see you?
Christian Sandrock, MD, FCCP
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