Getting a Grip on Influenza By Mark B. Levin, M.D. and Timothy J. Patrick-Miller, M.D.

What’s a flu?
Influenza, or "flu", is a specific disease caused by a specific virus. While we often refer to any virus as a "flu", this imprecision misleads people into believing that influenza has a more varied picture than it actually does and that it is prevalent over more of the year than it actually is (at least in most regions). It is far more appropriate to term other viral diseases by their specific designation (e.g., gastroenteritis or a cold). In some regions, influenza is referred to as "the grip". You will see why this is so two paragraphs hence.

Most outbreaks of influenza in the northern and southern hemispheres occur in the winter of those respective regions. In the tropics, influenza circulates year-round. Humans are the source of influenza B viruses for other humans. Horses, swine, chickens and ducks may share influenza A with humans and are believed to be responsible for "antigenic shift" (see below), particularly in the far east, where humans live in close contact with these animals. Influenza is transmitted from human to human via respiratory secretions. The two factors that make it so contagious are the prominent cough associated with the disease and the hardiness of the virus. As noted in commercial advertisements for cough medicines, a cough can spread respiratory droplets two or three yards in the air, broadcasting virus-laden secretions far and wide. Furthermore, whereas most viruses in respiratory droplets that land on surfaces, such as a kitchen countertop, become non-infectious after a few hours of exposure to the drying effects of air, influenza viruses remain viable for many hours. Hence, if you cough in the kitchen on Wednesday, someone else’s food placed on the countertop the next day can become contaminated with the virus. Now you know why your mother always admonished you to cover your mouth when you cough and wash your hands!

In the "Grip" of Flu
Symptoms of influenza are remarkably consistent from person to person and from year to year, enabling physicians to make a clinical diagnosis with reasonable certainty in an otherwise healthy individual. Pre-existing conditions, such as asthma, heart disease, or diabetes, can present a confounding picture that might necessitate laboratory testing or x-rays to sort out. Typically, a patient infected with influenza experiences an abrupt onset of headache, malaise, achiness and fever, perhaps after a few days of a mild runny nose (the symptoms make the victim feel caught in the "grip" of the illness, hence the name.. Within hours to a day or two, the patient complains of photophobia (eyes hurting when exposed to light) and compulsive, sometimes convulsive fits of non-productive coughing. Loss of appetite is common. Mild gastrointestinal upset sometimes accompanies the respiratory symptoms. At the height of the symptoms, a patient usually wants to be left alone in a quiet, dark room to sleep or to contemplate why life is so cruel as to inflict such an uncomfortable disease seems to drag on interminably! The symptoms fluctuate, being worse during the evening and night and when the fever rises. The three to five days during which these symptoms persist seem like a month to the ailing victim. The resolution of these symptoms for a day or two leads the patient to believe that the illness and contagion have passed. As nature would have it, the symptoms return for another two to four day’s encore performance. Only then do the acute symptoms end, but not without leaving influenza’s parting gift – a cough which lingers for a week or two!

How to Treat Influenza Well
Influenza often disrupts the protective mechanisms of the respiratory tract, which can then result in secondary bronchitis or pneumonia. Medical science has yet to discover an effective cure for influenza, so most of us employ home remedies: rest, fluids and pain relievers. Drinking plenty of fluids, both to maximize hydration and to thin respiratory secretions is critical. Bacteria that are trapped in respiratory secretions are more easily coughed up in less tenacious secretions, thereby preventing secondary infections. Small frequent doses of water, clear soup and sports drinks are the mainstays of fluid maintenance at home. Cough medicines are less effective at keeping secretions thin than water. Cough suppressants are sometimes helpful later in the course of influenza when the irritation in the healing trachea causes a constant reflex cough.

Analgesics, medications that alleviate pain, are often used during the course of influenza because the headache and body aches are so bothersome. While these medications have a secondary effect of lowering fever in many conditions, their effect on the fever of influenza is marginal. Although many parents are haunted by tales of brain damage caused by "high" fever, having a fever is actually helpful. As a normal part of the human immunologic response to infections, fever causes a series of physiologic events that actually helps fight off the infection. Unless there is some compelling medical reason to lower the temperature, current recommendations are to administer analgesics based only the need to relieve discomfort. If the patient is warm, but comfortable, analgesics are not necessary. In fact, they may even be undesirable. In one study in children, regular administration of analgesic medication during the course of influenza appeared to prolong the disease. This makes sense in light of our current understanding of how fever works to help us. The opposite extreme is undesirable, as well. Bundling a child during a fever, as was done in prior generations to make him or her "sweat out" the illness, can drive temperatures up to dangerous levels that would otherwise not be achieved by nature alone. This practice should not be employed. Among the available analgesics, acetaminophen and non-steroidal anti-inflammatory drugs, such as ibuprofen, are acceptable, but aspirin is not. Although often used until the mid to late twentieth century, aspirin must never be used to treat influenza. Medical researchers discovered in the 1970s that aspirin use in influenza may trigger a serious, often fatal, condition called Reye Syndrome. Since aspirin use in fever-associated diseases and chicken pox has been discontinued, Reye Syndrome is now a rarity.

Another inadvisable practice employed by some parents is alternating acetaminophen and ibuprofen at two-to-four hourly intervals in an effort to abate fever. As is clear from the preceding discussion, this approach is unnecessary and has the potential to cause liver damage. If fever is a true concern for a particular child, a tepid sponge bath coupled with administration of adequate doses of one analgesic/antipyretic will usually keep the fever within an acceptable range. Check with your child’s physician regarding the optimal dose for these medications, as the dosage printed on the label of the medication bottle or box may not be adequate for children of all weights in a given age range.

There are two sub-types of influenza which cause epidemics, called "A" and "B". Most of the influenza in the USA is caused by different strains of "A" (i.e., H1N2, Hong Kong, Fujian, etc.). Of course, when you have the flu, you don’t much care which strain you have – flu is flu; you just want it to go away! The distinction is important, however, for a few reasons. Generally, influenza "B" causes more severe and prolonged symptoms, lasting about ten days as compared to the five to seven day course of influenza "A". Antiviral medications and injectible vaccines are currently available for treatment and prevention of influenza "A" are ineffective against influenza "B". Your doctor can order a simple test at a medical laboratory to determine if you have influenza and which type is present.

Medications available for treatment and prevention of influenza act to inhibit viral replication in the hope that the patient’s immune system will then have an easier time eliminating the virus from the body. Tamiflu® (oseltamivir), Relenza® (zanamivir), Flumadine® (rimantidine), and Symmetrel® (amantadine), each have their own constraints for use (age, dose and timing restrictions). If taken as a preventative when another person in the household acquires influenza, it can be very effective. For any of them to offer a benefit once sypmtoms develop, they must be administered with 48 hours of onset of symptoms. They may confer a foreshortening of the illness by up to two days – not much overall benefit. But for those with time constraints in their daily life or those with complicated underlying conditions, these medications can be instrumental. Your doctor can advise you as to whether you are a candidate for one of these prescriptions and can describe the potential side effects of treatment in detail.

Prevention is the Best Approach
The more conventional medical intervention to prevent influenza is immunization. The menu of influenza immunizations includes several varieties of killed injectible vaccines and a new live-attenuated nasally inhaled vaccine. The killed injectible vaccine is manufactured in a whole virus version and a disrupted virus version (termed split-virus). The split virus version is the only one that is approved for use in children, and only some of the brands of these are suitable for children under four years of age. Most of the brands intended for young children no longer contain thimersol, a mercury-containg preservative. You health care provider can tell you which brand s/he uses and describe its characteristics.

Killed influenza vaccine is manufactured from virus particles that are harvested from an area of infection, purified and distributed to manufacturers for production. Unfortunately, influenza virus has a nasty habit of changing its genetic characteristics (called "mutation" or "antigenic drift") as it circles the globe. Since the purification and manufacturing process takes six to eight months, it starts in advance of the time that experts predict influenza outbreaks will occur. Manufacturers estimate how much vaccine will be needed for a particular winter and produce only that amount. If there is a shortfall for any reason, some of the population will not be immunized. For economic reasons, manufacturers prefer not to make more than is needed. Left over vaccine can not be used in subsequent years. About every ten years, strains of influenza A virus mutate so much (called "antigenic shift") during the time it takes to make the vaccine, that the vaccine is of limited value.

Because of this uncertainty, traditional medical recommendations for immunization have included only people who are at risk either for complications or a more severe case of influenza due to their basic medical status or because of their living conditions. High risk groups include people with pulmonary diseases (such as asthma or reactive airway disease, emphysema, chronic bronchitis or cystic fibrosis), metabolic diseases (such as diabetes), neurologic disease (such as a seizure disorder), heart disease (such as coronary disease, congenital malformations, cardiomyopathy, dysrhythmias, congestive heart failure), chronic diseases of an organ (such as chronic renal failure) or those in certain age groups (over fifty years and between six months and two years). Children in day care, children living in a dormitory or like group setting and people who live in a home with someone else who has an immunologic susceptibility to infections are included in the recommendations. No influenza vaccine has yet been approved in infants under six months of age. If you are unsure if you or a family member fall into a high risk group, you should consult your physician. Killed injectible influenza vaccine is usually available for use in October or November of each year.

A live-attenuated (made milder in the manufacturing process, but stimulating immunity because it actually causes infection) influenza vaccine was approved by the FDA in October of 2002 and released for sale in January of 2003. Is differs from the killed vaccines in that it is approved for use only in otherwise healthy individuals between the ages of five and forty-nine years old. It is available throughout the year. It, too, is updated yearly to include newly mutated strains. It is administered by a physician by nasal inhalation. Because it may exacerbate respiratory conditions, such as asthma, it is not to be given to people in high risk groups. Infectious disease experts theorize that if the healthy population is protected, there will be fewer sources of infection for those at high risk. The recommendations made by government officials for the entire population to be immunized are based on this theory and their charge to formulate policies that minimize health care expenditures, rather than on considerations of any individual’s medical condition. In pre-marketing data submitted to the FDA covering thousands of doses, the vaccine seems safe if administered according to the official guidelines. Caution is appropriate, however, as sometimes unsuspected complications are discovered when millions of doses are administered in the post-marketing situation. Your physician can tell you whether you or a family member fit a specific situation wherein the live attenuated vaccine is appropriate.

The Hype is Hyper
The media has made a publicity issue of complications and deaths from the 2003-2004 yearly influenza outbreak in this country. Our intent is certainly not to minimize the suffering of these unfortunate souls and their families, but rather to point out that the statistical incidence of complications and deaths from influenza is following a similar trend to that which has been found regularly in past years. That, by itself, is good cause for us all to consider influenza immunization, but with the same level of concern that we have had in previous years. The predominant cause of demise from influenza is pneumonia caused by a staphylococcal bacterium that is resistant to many antibiotics. This germ is primarily found (and acquired) in hospitals (where antibiotic use is far in excess of what is found in the community). The goal for all of us, then, should be to keep ourselves well enough to avoid hospitalization. That means immunizing high risk individuals and encouraging others who may acquire influenza to drink lots of fluids, thereby lessening the chance that respiratory secretions will stagnate in the lungs. A secondary infection with a community-acquired germ is far more likely to respond to simpler antibiotic treatment than the hospital-acquired type. This differs markedly from the 1918 influenza epidemic wherein many people died from community-acquired pneumonia because antibiotics and aggressive modes of supportive care had not yet been discovered.

If you or a family member are unlucky enough to acquire influenza and the course is different than that described above, there is a pre-existing medical condition or you simply want to check on what to expect, call your doctor. As always, during influenza outbreaks, as well as at other times, good hygienic practices will serve you well. So, cover your mouth, wash your hands and put up a pot of chicken soup!

Updated information on influenza can be found on the Internet at www.cdc.gov/flu/. Expert opinion on various topics in Infectious Disease, including influenza, can be found at www.isid.org.

Dr. Levin has been a member of the staff at The Pediatric Group since 1977. Currently an attending Pediatrician at the Medical Center at Princeton, he has been Chairman, Department of Pediatrics, Medical Center at Princeton, 1984 to 1986, 1989 to 1992, and past President, Medical and Dental Staff, Medical Center at Princeton, 1987 to 1988. Dr. Levin has served on numerous Departmental and hospital committees. He has published original articles both while at Upstate Medical Center in Syracuse and at The Pediatric Group. He has a wife and three children. Dr. Levin enjoys alpine skiing, jogging, hiking and camping, travel, computers and racquetball.

Dr. Patrick-Miller has been a member of the staff at The Pediatric Group since 1985. Dr. Patrick-Miller has served on several Departmental and hospital committees. He has published original work while at The Pediatric Group. He and his wife enjoy travel. He also likes hiking, biking, gardening and reading.

© The Pediatric Group, P.A. 2004. All rights reserved.