Viruses cause a variety of illnesses in humans ranging from mild upper respiratory infections (URIs) to life-threatening pulmonary and extra-pulmonary diseases. Rhinoviruses, adenoviruses, respiratory syncytial virus (RSV), coronaviruses, and influenza viruses are the most common viruses infecting the respiratory tract. Among these rhinoviruses, RSV, and influenza viruses are common causes of wheezing in children. Recurrent infections with these viruses may play a role in the development of asthma.
Patients with asthma are more susceptible to contracting infections with the influenza virus. In addition, they are also more likely to develop serious complications from influenza. In fact, more than 75% of acute flare-ups of asthma are triggered by infections from influenza, RSV, or rhinovirus.
Infections typically occur in the United States between October and November with a peak infection rate between January and March. There are 3 strains of influenza viruses that cause human infections; influenza A, influenza B and influenza C.
Influenza A and B are typically associated with seasonal disease but also have been associated with several pandemics during the 20th century. For example, in 1918, the Spanish influenza (i.e., Spanish flu), a strain of H1N1 of influenza A, caused between 50 and 100 million deaths worldwide with a mortality rate of 2.5 to 3%. Most of the deaths occurred in adults between the ages of 20 and 40 years old. In 1957, the Asian influenza or Asian flu of the H2N2 strain of influenza A, caused between 1.5 and 2 million deaths. In 1968, the Hong Kong influenza (i.e., Hong Kong flu), a strain of H3N2 influenza A, caused over 1 million deaths.
Currently circulating influenza A viruses of the H1N1 variety are related to the 2009 H1N1 pandemic that emerged in the Spring of 2009 and caused a flu pandemic.
Influenza infection begins with invasion of the respiratory epithelium by the virus. This site in the respiratory system serves as a place for both viral replication and the resulting host’s immune response. Destruction of normal airway tissue and a pro-inflammatory immune response are the primary causes of symptoms associated with influenza infection.
The immune response of the host causes many of the symptoms associated with a viral respiratory infection and those associated with exacerbations of underlying asthma. Certain individuals seem to be at a higher risk for developing infections in the lower airway (i.e. lungs). For example, age less than 6 months old, second-hand smoke exposure, and genetic factors play a role in increasing the risk of infection. Allergic subjects are also more susceptible to infections due to an impaired immune response.
- Runny nose, stuffy nose, post-nasal drip
- Sore throat
- Fever, chills
- Vomiting, diarrhea
- Exacerbation of asthma symptoms
- Inflammation of the heart muscle
- Inflammation of the brain
Most cases of influenza are mild and symptoms usually resolve within 7 to 10 days. Symptomatic relief can be given by over-the-counter medications such as Tylenol (i.e., acetaminophen) in order to reduce fevers, chills and/or achiness. Inhaled medications such as albuterol (i.e., ProAir, Ventolin) are given to help relieve asthma-like symptoms which may include wheezing, chest tightness, coughing and/or shortness of breath. Rest and increased oral fluids may hasten the recovery process.
The indications for antiviral medications include patients that are at high risk of influenza-related complications including pregnant women, adults over 65 years of age, immunocompromised individuals, and those with chronic medical conditions such as asthma, chronic obstructive pulmonary disease (COPD), and diabetes. Antiviral medications should be used if an individual requires hospitalization, during severe or complicated infection, and during pregnancy. Many primary care physicians recommend antiviral therapy for other scenarios and individuals should check with their physician to see what they recommend.
Antiviral treatment works the best when begun soon after flu-like symptoms begin. When treatment is started within 2 days of developing flu-like symptoms, antiviral drugs can reduce fever and flu symptoms and shorten the duration of the illness. They also may decrease the risk of complications such as ear infections in children, respiratory complications requiring antibiotics, and hospitalizations in adults. Some of the antiviral medications used for the treatment of the flu are as follows:
- Tamiflu (i.e., oseltamivir) is available as a pill or liquid suspension and is FDA approved for the early treatment of the flu in individuals over the age of 2 weeks.
- Relenza (i.e., zanamivir) is a powder that is inhaled and approved for the early treatment of the flu in individuals 7 years of age and older. Relenza is administered using an inhaler device and is not recommended for individuals with breathing problems such as asthma or COPD.)
- Oseltamivir and zanamivir are given twice a day for 5 days.
- Xofluza (i.e., baloxavir) is a pill given as a single dose by mouth and is approved for early treatment of flu in people 12 years and older. Xofluza is not recommended for pregnant women, breastfeeding mothers, and outpatients with complicated or progressive illness.
- Rapivab (i.e., peramivir) is given intravenously by a primary care physician and is approved for the early treatment of flu in individuals 6 months of age and older.
Staying home as much as possible and avoiding contact with others will reduce the risk of acquiring an influenza infection.
Routine annual influenza vaccination (i.e., flu shots) is recommended for all persons 6 months of age and older. Many types of flu vaccines are licensed by the FDA this year with varying indications based on one’s age group and health status. Please see the following link for more information.
The board certified allergists at Black & Kletz Allergy treats both adults and children and will gladly answer any questions you have concerning the flu as well as any allergy/immunology topic. Black & Kletz Allergy has 3 offices in the Washington, DC, northern Virginia, and Maryland metropolitan area with locations in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. We offer on-site parking at each location and our Washington, DC and McLean offices are also Metro accessible. There is a free shuttle that runs between our McLean office and the Spring Hill metro station on the silver line. If you would like to make an appointment with an allergy specialist, please call us. Alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day. Black & Kletz Allergy has been providing quality allergy, asthma, sinus, and immunological services to the DC metro area for more than 5 decades