The seasonal flu is a respiratory infection caused by the influenza virus. Seasonal outbreaks occur most commonly in the fall and winter months. It is estimated that influenza affects over 200,000 people in the United States and causes approximately 36,000 deaths yearly. In those susceptible to influenza, it can cause complications such as ear and sinus infections, pneumonia, and the worsening of conditions like asthma and congestive heart failure.
There are 3 types of influenza virus (types A, B, and C). Type A is the most virulent. The flu has the ability to easily change and create multiple strains, which protects it from the body’s immune system. Some types of flu have caused global pandemics. The Spanish flu of 1918 (a strain of H1N1) lasted for 2 years and killed an estimated 50 to 100 million people. Some flu types have also been known to be able to infect different species, such as the “avian flu” (H5N1), which can spread from birds to humans. Recently, the emergence of the “swine flu” (another H1N1 strain) in 2009, to which many individuals may not be properly immune, sparked fears of another influenza pandemic.
Signs and Symptoms
Symptoms of seasonal flu may mimic the common cold. Several symptoms can help differentiate the two. Influenza presents most commonly with:
• Chills and body aches
• Nonproductive cough
• Severe chest discomfort
• Vomiting and diarrhea (more commonly in children)
• Very sudden onset of symptoms (within 3-6 hours)
It is important to remember that not all individuals experience the same symptoms. Even in the same individual the symptoms and severity of disease may not be the same each time he or she is infected.
Depending on the individual, the flu can be contagious before symptoms arise and up to a week after symptoms have resolved. Most experts believe that the flu can be spread when someone inhales droplets dispersed from infected individuals when they sneeze, cough, or talk. Individuals may also contract the flu virus from touching infected objects, because the virus can be transferred from the hands to the mouth or eyes. Because the influenza virus changes frequently, annual vaccinations are recommended, especially in certain populations who are at risk for flu complications:
• Patients with preexisting respiratory conditions (eg, asthma or chronic obstructive pulmonary disease)
• Children younger than 5 years of age and adults older than 65 years of age
• Caregivers of children less than 5 years of age
• Pregnant women
• Patients who may be immunosuppressed
• Patients with kidney or liver disease, sickle-cell anemia, or diabetes
• Patients who live in long-term care facilities
• Health care workers who attend to immunocompromised patients
There are 2 modes of delivering the flu vaccine.
• Intramuscular injection
: indicated for patients older than 6 months of age. This type of vaccine carries the inactivated or “killed” virus, so there is no risk of contracting the disease.
• Nasal spray
: carries the live-attenuated virus, which is a weakened form of the virus. The spray can be used for healthy, nonpregnant patients with a normal immune system between the ages of 2 and 49 years.
Pharmacists in all 50 states can now be licensed to administer vaccinations to patients who are aged 18 years and older. They can also serve to screen patients who may not be candidates to receive vaccinations, such as patients with egg allergies, those who had a severe reaction to a prior influenza vaccine, and those who developed Guillain-Barré syndrome within 6 weeks of a flu vaccination.
Treatment and Care
Just like the common cold, there is no cure for the flu at this time. The severity of the flu can depend on the individual’s immune system and the type of flu that infects an individual. OTC products such as antipyretics (eg, ibuprofen and acetaminophen) and antitussives (eg, dextromethorphan) can help to alleviate the symptoms of the flu. Prescription products like Tamiflu (oseltamavir) and Relenza (zanamavir) are antivirals indicated to treat and prevent the flu.
Seeking Medical Attention
A visit to the emergency department is only necessary for severe cases of influenza. Signs and symptoms of severe cases include:
• Confusion and other acute changes in mental status
• Symptoms that return with worsening symptoms
• Difficulty breathing
• Pain or pressure in the chest or abdominal area