Perception: "It's Just the Flu"
Facts:
- Influenza infects over 30 million people in the U.S. each year - that's 10-20% of the U.S. population.
- Over 150,000 people are hospitalized annually in the U.S. with complications from flu.
- Influenza and its complications are the sixth leading cause of death in the U.S., killing 20,000-40,000 people a year.
- 60% of those with influenza are misdiagnosed and begun on antibiotics.
- During the "flu season," emergency room wait-time commonly exceeds four hours and "true" emergencies have to be sent to other ER's.
- Business productivity drastically drops due to flu sick time.
- Total costs exceed $10,000,000,000 in the U.S.
Fact:Are we are overdue for another major epidemic?
- The influenza virus changes every year. Sometimes new strains come along and affect even the healthy.
- In some years, there are more drastic changes in the influenza virus - like the 1918 Spanish Flu that killed 500,000 people and the Asian Flu in 1957-58 that caused 70,000 deaths in the U.S. alone.
- Type A/Sidney, which was a new strain in the 1997-98 flu season, appears to have been responsible for almost double the average number deaths in the U.S. (average = 20,000).
- During these years, even healthy people are very sick.
Until the discovery of AIDS, influenza was the last uncontrolled pandemic
killer of humans. One historic measure of influenza's
potential lethality is that more people died in the 1918-19 pandemic than
in World War I. In the United States, influenza currently
causes more morbidity and mortality than AIDS. In non pandemic years, 10,000
to 20,000 people die of influenza related illness in
the U.S. In pandemic years, such deaths can exceed 100,000; the morbidity,
of course, far exceeds the mortality.
Influenza -- commonly shortened to "flu" -- is an extremely contagious viral disease that appears most frequently in winter and early spring. The infection spreads through the upper respiratory tract and sometimes goes into the lungs. The virus typically sweeps through large groups of people who share indoor space, such as schools, offices and nursing homes.
Influenza virus in humans is spread via respiratory secretions from infected persons, through coughing and sneezing. These aerosols of viruses contaminate the air, hands, and surfaces of our environment. The incubation period is very short (from 1 to 4 days), and attack rates range from 15-40% in a normal year. In nursing homes, 60 out of 100 patients can be affected, with up to 30 fatalities. A person over age 65 is at risk because the immune system is weakened and, over the years, "forgets" it has been exposed to influenza.Sick persons "shed" the virus and are contagious for about a week. Immunocompromised persons (e.g., those with cancer, AIDS, or who may be on immunosuppressants) easily contract influenza and shed virus for 2-3 weeks. School-age children are the first to become ill in each community and are the primary source of contagion since they shed virus for 7 to 10 days. Because they have little or no previous exposure to influenza, children have less immunity and can experience more severe forms of flu. Others at risk for serious influenza complications are patients with asthma, pulmonary disease, heart disease, diabetes, renal disease and anemia.
The simple, and surprising, answer is birds. Waterfowl to be exact. They are what virologists call the "reservoir" for influenza. They carry nearly all known types of influenza, with no ill effects, and willingly share them with the rest of the animal kingdom through their feces. All animals that get the flu - horses, ferrets, seals, pigs, among others -and human beings probably get it originally from birds.
Fortunately, we do not need to live in fear of all contact with water fowl. Viruses can only infect and take over a cell if the proper "receptor" is present, and as far as we know human beings do not have a receptor for avian flu. What's needed for human infection is another species that has both human and avian flu receptors. In other words, the pig.
Having both human and avian receptors sets the pig up for all sorts of wonderful influenza possibilities. The process can be as simple as a flu contaminated duck dropping feces into the dirt a pig is rolling around in, thus infecting the pig who, in turn, passes the virus on to a farmer. It can also be more complex. It is possible for a pig to be infected with one kind of flu, say a human flu, only to contract another avian flu. Now the poor pig has two different types of flues simultaneously. When it proceeds to reinfect a human being, it passes on a pig-bird-human influenza. Add to this the fact that a flu virus consists of eight loosely bundled and interchangeable gene segments and it really gets interesting. The Hong Kong Flu, for example, held seven genes from a human virus, and one gene from a duck virus, that met inside of a pig to produce an entirely new hybrid.
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- Fever -- usually between 101° F and 102° F, but occasionally as high as 106° F -- sometimes alternating with chills.
- Sore throat.
- Dry, hacking cough.
- Aching muscles.
- General fatigue and weakness.
- Nasal congestion, sneezing.
- Headache.
Signs and Tests:
General Treatment
- nasopharyngeal culture
- throat culture
- influenza complement fixation
- febrile/cold agglutinins
- blood differential
The goal of treatment is to alleviate the symptoms.
Antiviral Agents
- Give ONLY non-aspirin medicines such as acetaminophen (Tylenol) to children for fever, muscle aches and headaches.
- Ibuprofen-containing pain relievers (e.g., Advil or Motrin) can be used for fever and pain in older adolescents and adults.
- Drink plenty of fluids to prevent secretions from getting thick and increasing breathing problems.
- Rest to help your body fight the infection.
- Antiviral medicines can be used. See below.
- Antibiotics are of absolutely no use for influenza and are used only for bacterial complications after the acute phase is over.
The New Flu Drugs - Neuraminidase Inhibitors
Complications:
- An exciting new class of drugs is just now becoming available for the treatment of influenza. These drugs, called neuraminidase inhibitors, help stop influenza virus replication and are active against influenza types A and B.
- Zanamivir for inhalation (Relenza®, a trademark of GlaxoWellcome) is the first of these new drugs to be approved by the FDA.
- Relenza has been shown to shorten the duration of flu symptoms if given within 48 hours of symptom onset.
- Thus it is important to see your doctor at the first sign of flu symptoms to receive effective treatment.
Secondary bacterial infection Bronchitis Pneumonia
Call the health care provider if symptoms of the flu do not improve after 7 to 10 days, or if cough becomes productive of brown or green sputum, or if difficulty breathing develops.
The prevention mainstay of influenza is the yearly vaccine. This vaccine can reduce the number of illnesses and deaths. The influenza vaccine is specifically recommended for people who are at high risk for developing serious complications as a result of flu infection. Since the immunity provided by the vaccine wanes after several months, it is given at the beginning of the "flu season"--usually late October or early November in the U.S. People traveling to other countries should be aware that influenza occurs throughout the year in tropical countries and that the "flu season" for temperate countries in the Southern Hemisphere is April to September. Visit THIS web site for more comprehensive information on the vaccine.
There are several resources available to track the virus as it spreads during the flu season. Visit any of the following links for surveillance information in your area of interest.
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As mentioned in the title, the flu is the culprit of the worst health epidemic in the history of the U.S.
Mortality associated with pandemics:
For more information on the "Spanish Flu", visit the PBS American Experience web site.
- 1918-19 "Spanish flu" A(H1N1) -- Caused the highest known influenza related mortality: approximately 500,000 deaths occurred in the United States, 20 million worldwide.
- 1957-58 "Asian flu" A(H2N2) -- 70,000 deaths in the United States.
- 1968-69 "honking flu" A(H3N2) -- 34,000 deaths in the United States.
For a more recent account, read Time Magazines "Flue Hunters" edition, which describes an outbreak of the flu in Hong Kong that was compared to the 1918 "Spanish Flu".
I must to give credit where credit is due. Listed below are links to web site that contributed to the contents of this web page.
Table of contentsWTE - May 2000