True Flu

     With an apology to Dr. Suess for playing upon the title of his book, “One Fish, Two Fish, Red Fish, Blue Fish,” I have been surprised through my years of medical practice when patients have described their illness as “Head Flu, Chest Flu, Stomach Flu or Body Flu.”  The purpose of this article is to describe the “True Flu,” the particular illness of infection with influenza virus, so that you may recognize it and know what to do if you or a member of your family is unfortunate enough to become infected.

     The first thing to realize is that influenza is primarily a respiratory illness.  Sure, it may cause symptoms in other parts of the body, but the route of “catching” influenza is through your respiratory tract (nose, mouth, throat, bronchi.)  Have you ever seen a photograph or a slow-motion movie clip of a person coughing or sneezing?  Remember the cloud of respiratory droplets that exploded out of their face?  “Respiratory droplets” is a nice way of describing tiny droplets of mucus and saliva (yuk!) that are blown 6-10 feet away from such a person and hang in the air and fall on surfaces around them.  If you inhale some of these droplets from an infected person or touch a contaminated surface and then touch your eyes, nose or mouth, voila! you just contracted their illness.

     Respiratory droplets from a person infected with influenza are loaded with virus particles.  Viruses are made of protein fragments and are not really “alive” in the ordinary sense of the word – but, when they attach to and penetrate cells in our bodies, they make the cells produce gazillions of copies of the virus.  At some point, the cells rupture which releases a flood of newly made copies of the virus which can either invade nearby healthy cells or be expelled in respiratory droplets to infect other people.

     Once you understand the mechanisms of viral infection and replication, the clinical syndrome of influenza illness makes more sense.  Persons with influenza do not have just an isolated runny nose or an isolated sore throat or just an isolated cough – there will be evidence of infection of the entire respiratory tract, top to bottom, along with whole-body symptoms.  After an infection event, there is an incubation period of 18-72 hours after which the first crop of infected cells start to rupture and die … that’s when the symptoms start.  A person with influenza experiences abrupt onset of fever, chills, headache, malaise, sore throat and muscle aches.  Indeed, many patients describe the onset of their illness in terms such as, “I was fine at noon and sick as a dog by three o’clock,” or “I went to bed feeling normal and woke up at two o’clock in the morning feeling like I’d been run over by a truck.”  Fever typically lasts about 3 days, but may persist for 5-7 days.  Headache and muscle pain usually resolves along with the fever.  Cough and fatigue usually resolve over 2 weeks, but may last even longer.

     Many of the various symptoms of influenza are explained by our bodies’ response to the infection.  Fever is part of your immune response to the infection – it actually helps you, but makes you feel terrible.  Myalgias (diffuse muscle aches) are part of our inflammatory response to the infection.  Red eyes, runny nose, sore throat and cough are caused by damage to the cells that line the respiratory tract and outer layer of the eyes.  Cough is related to excessive mucus secretion within the bronchi and sloughing of the dead cells that line the respiratory tract (think of something like a peeling sunburn within the back of your nose and in your throat and bronchi – double yuk!!)  Even people without asthma may feel short of breath and have wheezing due to accumulated mucus and cellular debris within their bronchi.  Although influenza is a respiratory illness, nausea, vomiting and diarrhea may occur.  This is usually a more common feature of the illness in children than adults but, interestingly, the new H1N1 flu seems to have a higher frequency of GI complaints in adults than the ordinary seasonal influenza.

     There are some symptoms that may indicate complications of influenza and prompt urgent medical evaluation.  Shortness of breath, new onset wheezing, purulent (pus-like) sputum, bloody sputum, fever lasting longer than a week, brownish urine, severe muscle pain and true muscular weakness are examples of symptoms that may indicate severe complications and possible need for hospitalization.

     So ….  what can you do if you are slimed by someone shedding flu viruses?  Most of the symptomatic and supportive measures are things your grandmother would have advised.  Rest is important.  Fighting the infection takes a lot of energy, so it’s helpful to conserve your body’s resources – reduce exertion and sleep more.  Increase your fluid intake – if your urine is darker than just a tinge of yellow, increase your hydration.  Don’t get behind on food intake – even when you’re not sick, remember how bad you feel if you skip 2 meals in a row?  With the increased metabolism needs of fever, you need to maintain adequate calorie intake.  Acetaminophen can help reduce headache, fever and muscle pain.  Unless you have a reason not to take them, anti-inflammatory medications (such as naproxen or ibuprofen) may also help reduce discomfort.  Do everyone else a favor and stay home until you are better!  Viral shedding is greatest for the first 2 days after symptoms begin, but may persist for 5-10 days.

     There are now several antiviral drugs for the treatment of influenza: some work for influenza type A and some work for both influenza types A and B.  The cost and potential side effects are variable between the different drugs and the details of their choice and use are too lengthy for the purpose of this article.  In general, however, there are two features of antiviral drug therapy of which you should be aware: firstly, they are not a “cure” for the illness - they reduce fever and shorten the duration of illness by 1-2 days and may reduce viral shedding (infection potential to other people); and secondly, their benefits are most pronounced when started within 24-48 hours of onset of the illness (when virus replication is most active.)

     The best defense against influenza is prevention.  Unless you have a specific condition that makes immunization risky, get a flu shot!  This year, it seems you might need 3 shots: 1 for the “usual” seasonal influenza and 2 for the H1N1 strain.  Information regarding personal hygienic measures is widely distributed.  The Centers for Disease Control and Prevention (cdc.gov) has extensive information available for persons who wish to learn more about the “True Flu.”