Printer Friendly


Chronic Fatigue Syndrome

What Is Chronic Fatigue Syndrome?

We all get tired. Many of us at times have felt depressed. But the mystery known as chronic fatigue syndrome (CFS) is not like the normal al ups and downs we experience in everyday life. The early sign of this illness is a strong and noticeable fatigue that comes on suddenly and often comes and goes or never stops. You feel too tired to do normal activities or are easily exhausted with no apparent reason. Unlike the mind fog of a serious hangover, to which researchers have compared CFS, the profound weakness of CFS does not go away with a few good nights of sleep. Instead, it slyly steals your energy and vigor over months and sometimes years.

How CFS Begins and Its Symptoms

For many people, CFS begins after a bout with a cold, bronchitis, hepatitis, or an intestinal bug. For some, it follows a bout of infectious mononucleosis, or mono, which temporarily saps the energy of many teenagers and young adults. Often, people say that their illnesses started during a period of high stress. In others, CFS develops more gradually, with no clear illness or other event starting it.

Unlike flu symptoms, which usually go away in a few days or weeks, CFS symptoms either hang on or come and go frequently for more than six months. CFS symptoms include:

* Headache

* Tender lymph nodes

* Fatigue and weakness

* Muscle and joint aches

* Inability to concentrate

Who Gets CFS?

CFS was once stereotyped as a new "yuppie flu" because those who sought help for and caused scientific interest in CFS in the early 1980s were mainly well-educated, well-off women in their thirties and forties. Similar illnesses, known by different names, however, date back at least to the late 1800s. The modern stereotype arose. Since then, doctors have seen the syndrome in people of all ages, races, and social and economic classes from several countries around the world.

Still, CFS is diagnosed two to four times more often in women than in men, possibly because of biological, psychological, and social influences. For example,

* CFS may have a gender difference similar to diseases such as systemic lupus erythematosus and multiple sclerosis, which affect more women than men.

* Women may be more likely than men to talk with their doctors about CFS-like symptoms.

* Some members of the medical community and the public do not know about or are skeptical of the syndrome.

* An increasingly diverse patient group will likely emerge as more doctors see CFS as a real disorder.

How Many People Have It?

Because there is no specific laboratory test or clinical sign for CFS, no one knows how many people this illness affects. CDC estimates, however, that as many as 500,000 people in the United States have a CFS-like condition.

What Causes CFS?

While no one knows what causes CFS, for more than a century, doctors have reported seeing illnesses similar to it. In the 1860s, Dr. George Beard named the syndrome neurasthenia because he thought it was a nervous disorder with weakness and fatigue. Since then, health experts have suggested other explanations for this baffling illness:

* Iron-poor blood (anemia),

* Low blood sugar (hypoglycemia),

* Environmental allergy, or

* A body wide yeast infection (candidiasis).

In the mid-1980s, the illness became labeled "chronic EBV" when laboratory clues led scientists to wonder whether the Epstein-Barr virus (EBV) might be causing this group of symptoms. New evidence soon cast doubt on the theory that EBV could be the only thing causing CFS. High levels of EBV antibodies (disease-fighting proteins) have now been found in some healthy people as well as in some people with CFS. Likewise, some people who don't have EBV antibodies, and who thus have never been infected with the virus, can show CFS symptoms.

How Is CFS Diagnosed?

Doctors find it difficult to diagnose CFS because it has the same symptoms as many other diseases. When talking with and examining you, your doctor must first rule out diseases that look similar, such as multiple sclerosis and systemic lupus erythematosus in which symptoms can take years to develop. In follow-up visits, you and your doctor need to be alert to any new cues or symptoms that might show that the problem is something other than CFS.

When other diseases are ruled out and if your illness meets other criteria as well, your doctor can diagnose you with CFS (see The CFS Case Definition).

The CFS Case Definition

The EBV work sparked new interest in the syndrome among a small group of medical researchers. They realized they needed a standard way to describe CFS so that they could more easily compare research results.

In the late 1980s, CDC brought together a group of CFS experts to tackle this problem. Based on the best information available at the time, this group published in the March 1988 issue of the scientific journal, Annals of Internal Medicine, strict symptom and physical criteria - the first case definition - by which scientists could evaluate CFS study patients.

Not knowing the cause or a specific sign for the disease, the group agreed to call the illness "chronic fatigue syndrome" after its primary symptom. "Syndrome" means a group of symptoms that occur together but can result from different causes. (Today, CFS also is known as myalgic encephalomyelitis, postviral fatigue syndrome, and chronic fatigue and immune dysfunction syndrome.)

After using this definition for several years, CFS researchers realized some criteria were unclear or redundant. An international group of CFS experts reviewed the criteria for CDC, which led to the first changes in the case definition. This new definition was published in the same journal in December 1994.

Besides revising the CFS case criteria - which reduced the required minimum number of symptoms to four out of a list of eight possible symptoms - the newer report also proposed a conceptual outline for studying the syndrome. This outline recognizes CFS as part of a range of illnesses that have fatigue as a major symptom. Although primarily intended for researchers, these guidelines should help doctors better diagnose CFS.

How Can I Cope With and Manage the Illness?

There is no effective treatment for CFS. Even though there is no specific treatment for CFS itself, you may find it quite helpful to treat your symptoms. Nonsteroidal anti-inflmnmatory drugs, such as ibuprofen, may help get rid of any body aches or fever, and nonsedating antihistamines may help relieve any prominent allergic symptoms, such as numy nose.

Learning how to manage your fatigue may help you improve the level at which you can function and your quality of life despite your symptoms. A rehabilitation medicine specialist can evaluate and teach you how to plan activities to take advantage of times when you usually feel better.

The lack of any proven effective treatment can be frustrating to both you and your doctors. If you have CFS, health experts recommend that you try to maintain good health by:

* Eating a balanced diet and getting adequate rest.

* Exercising regularly but without causing more fatigue.

* Pacing yourself - physically, emotionally, and intellectually - since too much stress can aggravate your symptoms.

The course of CFS varies from patient to patient. For most people, CFS symptoms plateau early in the course of illness and thereafter wax and wane. Some people get better completely, but it is not clear how frequently this happens. Emotional support and counseling can help you and your loved ones cope with the uncertain outlook and the ups and downs of this illness.

Although new studies seem to show that cognitive behavioral therapy and graduated exercise programs can greatly help many. Others are helped by antidepressants.

Because well-designed clinical studies have found that patients with fibromyalgia (an illness similar to CFS) benefit from low-dose tricyclic antidepressants, doctors often prescribe these drugs for people with CFS with generally positive results. Some researchers believe that these drugs improve the quality of sleep. Patients also have benefited from other kinds of antidepressants, including the newer serotonin reuptake inhibitors. Therapeutic doses of antidepressants often increase fatigue in CFS, so doctors may have to increase the dosage very slowly, or prescribe more active antidepressants. In addition, some people with CFS benefit from the benzodiazepines, a class of drugs used to treat acute anxiety and sleep problems. Patients often try more than one drug before finding one that works and can be tolerated.


CFS seems to involve interactions between the immune and central nervous systems, interactions about which scientists know relatively little. Scientists' concerted efforts to penetrate the complex nervous system and immune system events in CFS have created a challenging new concept of the pathology of this and other illnesses.

For More Information About CFS, Contact:

Centers for Disease Control and Prevention 1500 Clifton Road NE Atlanta, GA 30333 1-800-232-3228

NIAID is a component of the National Institutes of Health (NIH). NIAID supports basic and applied research to prevent, diagnose, and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, tuberculosis, malaria, autoimmune disorders, asthma and allergies.

Prepared by: Office of Communications and Public Liaison National Institute of Allergy and Infectious Diseases National Institutes of Health Bethesda, MD 20892

Public Health Service U.S. Department of Health and Human Services November 2000

Publications Home Centers for Disease Control and Prevention Chronic Fatigue Syndrome (CFS) Page


Influenza, or the flu, is a respiratory infection caused by a variety of flu viruses. The most familiar aspect of the flu is the way it can "knock you off your feet" as it sweeps through entire communities.

The flu differs in several ways from the common cold, a respiratory infection also caused by viruses. For example, people with colds rarely get fevers or headaches or suffer from the extreme exhaustion that flu viruses cause.

The U.S. Centers for Disease Control and Prevention (CDC) estimates that 35 to 50 million Americans come down with the flu during each flu season, which typically lasts from November to March. Children are two to three times more likely than adults to get sick with the flu, and children frequently spread the virus to others. Although most people recover from the illness, CDC estimates that in the United States more that 100,000 people are hospitalized and more than 20,000 people die from the flu and its complications every year.

When and Where Do People Usually Get the Flu?

Flu outbreaks usually begin suddenly and occur mainly in the late fall and winter. The disease spreads through communities creating an epidemic. During the epidemic, the number of cases peaks in about three weeks and subsides after another three or four weeks. Half of the population of a community may be affected. Because schools are an excellent place for flu viruses to attack and spread, families with school-age children have more infections than other families, with an average of one-third of the family members infected each year.

Is the Flu an Important Disease?

Besides the rapid start of the outbreaks and the large numbers of people affected, the flu is an important disease because it can cause serious complications. Most people who get the flu get better within a week (although they may have a lingering cough and tire easily for a while longer). For elderly people, newborn babies, and people with certain chronic illnesses, however, the flu and its complications can be life-threatening.

How is the Flu Transmitted?

You can get the flu if someone around you who has the flu coughs or sneezes. You can get the flu simply by touching a surface like a telephone or door knob that has been contaminated by a touch from someone who has the flu. The viruses can pass through the air and can enter your body through your nose or mouth. If you've touched a contaminated surface, they can pass from your hand to your nose or mouth.

You are at greatest risk of getting infected in highly populated areas, such as in crowded living conditions and in schools.

What are Flu Symptoms?

If you get infected by the flu virus, you will usually feel symptoms one to four days later. You can spread the flu to others before your symptoms start and for another three to four days after your symptoms appear. The symptoms start very quickly and are

* Headache

* Chills

* Dry cough

* Body aches

* Fever

* Stuffy nose

* Sore throat

Typically, the fever begins to decline on the second or third day of the illness. The flu almost never causes symptoms in the stomach and intestines. The illness that some people often call "stomach flu" is not influenza.

How Does a Doctor Diagnose the Flu?

Usually, doctors or other health care workers diagnose the flu on the basis of whether flu is epidemic in the community and whether the patient's complaints fit the current pattern of symptoms. Doctors rarely use laboratory tests to identify the virus during an epidemic. Health officials, however, monitor certain U.S. health clinics and do laboratory tests to determine which type of flu virus is responsible for the epidemic.

How Can I Keep from Getting the Flu?

Flu Vaccine

The main way to keep from getting the flu is to get a yearly flu vaccine. You can get the vaccine at your doctor's office or a local clinic, and in many communities at work places, supermarkets, and drugstores. You must get the vaccine every year because it changes.

Scientists make a different vaccine every year because the strains of flu viruses change from year to year. Nine to 10 months before the flu season begins, they prepare a new vaccine made from inactivated (killed) flu viruses. Because the viruses are killed, they cannot cause infections. The vaccine preparation is based on the strains of the flu viruses that are in circulation at the time. It includes those A and B viruses (see section below on types of flu viruses) expected to circulate the following winter.

Sometimes, an unpredicted new strain may appear after the vaccine has been made and distributed to doctors and clinics. Because of this, even if you do get the flu vaccine, you still may get infected. If you do get infected, however, the disease usually is milder because the vaccine still will give you some protection.

Your immune system takes time to respond to the flu vaccine. Therefore, you should get vaccinated six to eight weeks before flu season begins to prevent getting infected or reduce the severity of flu if you do get it. The vaccine itself cannot cause the flu, but you could become exposed to the virus by someone else and get infected soon after you are vaccinated.

Are there possible side effects from the flu vaccine?

You should be aware that the flu vaccine can cause side effects. The most common side effect in children and adults is soreness at the site of the vaccination. Other side effects, especially in children who previously have not been exposed to the flu virus, include fever, tiredness, and sore muscles. These side effects may begin 6 to 1.2 hours after vaccination and may last for up to two days.

Viruses for producing the vaccine are grown in chicken eggs and then killed with a chemical so that they can no longer cause an infection. The flu vaccine may contain some egg protein, which can cause an allergic reaction. Therefore, if you are allergic to eggs or have ever had a serious allergic reaction to the flu vaccine, CDC recommends that you consult with your doctor before getting vaccinated.

Who should get the flu vaccine?

If you are in any of the following groups or live in a household with someone who is, CDC recommends that you get the flu vaccine.

* You are 50 years of age or older.

* You have chronic diseases of your heart, lungs, or kidneys.

* You have diabetes.

* Your immune system does not function properly.

* You have a severe from of anemia.

* You will be more than three months pregnant during the flu season.

* You live in a nursing home or other chronic-care housing facility.

Children should get the flu vaccine if they are taking long-term aspirin treatment as they may be at risk of developing Reye's syndrome following a flu infection (see section on complications in children). They should also get the flu vaccine if they live in a household with someone in the above groups.

Health care workers and volunteers should get the flu vaccine if they work with patients in any of the above groups.

Medicine for Prevention

Although the flu vaccine is the best way to prevent getting the flu, three antiviral medicines also are available by prescription that will help prevent flu infection:

* Tamiflu[R] (oseltamivir)

* Flumadine[R] (rimantadine)

* Symmetrel[R] (amantadine)

The Food and Drug Administration (FDA) has approved Tamiflu[R] for use in adults and adolescents 13 years and older. Rimantadine and amantadine have been approved for use by adults and children who are 1 year of age and older.

Rimantadine and amantadine have unpleasant side effects. Your doctor can help you decide which medicine is best for you.

* These medicines help prevent the flu if you take them for at least two weeks during the outbreak of flu in your community.

* You may use these medicines if you are in close contact with family members or others who have the flu.

* You may use them if you are in close contact with people who have been vaccinated but whom you want to give added protection from getting the flu.

* You may use either medicine immediately following flu vaccination during a flu epidemic to protect you during the two- to four-week period before antibodies (proteins from your immune system that protect you from the flu virus) develop or when a flu epidemic is caused by virus strains other than those covered by the vaccine.

You should discuss the flu vaccine and the medicines with your doctor before the flu season begins.

What is the Treatment for the Flu?

Many people treat their flu infections by simply

* Resting in bed

* Drinking plenty of fluids

* Taking over-the-counter medicine such as aspirin or acetaminophen (Tylenol[R], for example)

You should not give aspirin to children and adolescents who have the flu.

You should not take antibiotics to treat the flu because they do not work on viruses. Antibiotics only work against some infections caused by bacteria.

Medicine for Treatment

If you do get the flu and want to take medicine to treat it, your doctor may prescribe one of four available antiviral medicines:

* Tamiflu[R] (oseltamivir) helps adults 18 years and older and Relenza[R] (zanamivir) helps adults and children 7 years and older who have an uncomplicated flu infection and who have had symptoms for no more than two days. FDA recently approved Tamiflu[R] for use in children 1 year of age and older who have had symptoms for no more than two days. Both treat influenza type A and type B infections.

* Flumadine[R] (rimantadine) helps adults who have influenza type A virus infections. It has no effect on influenza type B virus infections.

* Symmetrel[R] (amantadine) can be taken by adults and children who are 1 year of age and older to prevent and treat type A or type B influenza virus infections. Amantadine, however, is more likely to cause side effects such as lightheadedness and inability to sleep more often than is rimantadine.

To work well, you must take these medicines within 48 hours after the flu begins. They reduce the length or time fever and other symptoms last and allow you to return to your daily routine quicker. What are Possible Complications from the Flu?

You can have flu complications if you get a bacterial infection, which causes pneumonia in your weakened lungs. Pneumonia also can be caused by the flu virus itself.

Symptoms of complications will usually appear after you start feeling better. After a brief period of improvement, you may suddenly get

* High fever

* Shaking chills

* Chest pain with each breath

* Coughing that produces thick, yellow-greenish-colored mucus

Pneumonia can be a very serious and sometimes life-threatening condition. If you have any of these symptoms, you should contact your doctor irmnediately so that you can get the appropriate treatment.

Are There Other Flu Complications that Only Affect Children?

Reye's syndrome, a condition that affects the nerves, sometimes develops in children and adolescents who are recovering from the flu. Reye's syndrome begins with nausea and vomiting, but the progressive mental changes (such as confusion or delirium) cause the greatest concern.

The syndrome often begins in young people after they take aspirin to get rid of fever or pain. Although very few children develop Reye's syndrome, you should consult a doctor before giving aspirin or products that contain aspirin to children. Acetaminophen does not seem to be associated with Reye's syndrome.

Other complications of the flu that affect children are

* Convulsions caused by fever

* Croup

* Ear infections, such as otitis media

Newborn babies recently out of intensive care units are particularly vulnerable to suffering from flu complications.

Are There Different Types of Flu Viruses?

The first flu virus was identified in the 1930's. Since then, scientists have classified flu viruses into types A, B, and C.

Type A is the most common and usually causes the most serious epidemics. Type B outbreaks also can cause epidemics, but the disease it produces generally is milder than that caused by type A. Type C viruses, on the other hand, never have been connected with a large epidemic.

Flu Pandemics in the 20th Century

If a flu virus emerges that is either new or that has not circulated in many years, and if it is able to spread easily from person to person, it could quickly travel around the world and cause serious illness and death for millions of people. This is called a flu pandemic.

The 1918 Spanish flu pandemic is the catastrophe against which all modern pandemics are measured. More than 20 million people were killed worldwide; 500,000 died in the United States alone. This virus was especially quick to kill. So far, the world has not seen a virus that severe again.

In 1957 and 1968, the Asian flu and Hong Kong flu, respectively, invaded the United States. Although hundreds of thousands of people in the United States died, the death toll for each pandemic was not as high as that for the Spanish flu.

In 1976, the United States experienced a swine flu scare. When a new flu virus was first identified at Fort Dix, New Jersey, it was labeled the "killer flu," and health experts were afraid that it would infect people around the world. In fact, swine flu never left the Fort Dix area. Research on the virus later showed that if it had spread, it would probably have been much less deadly than the Spanish flu.

In 1997, another "near miss" pandemic occurred when 18 people in Hong Kong became ill from a new flu virus. Six of the infected people subsequently died. Usually, flu viruses move first from chickens to pigs, and then from pigs to humans. This virus was different because it moved directly from chickens to people. The avian flu never became a pandemic, however, because it didn't easily spread from person to person. In addition, public health authorities ordered the slaughter of all live chickens in Hong Kong.

What Research is Going On?

Although flu epidemics pop up in the fall and winter seasons in communities throughout the world every year, including the United States, there has not been a pandemic since 1968. Scientists are worried that a new flu virus will emerge in the 21st century and cause a severe pandemic again. For this reason, research institutions and health departments around the world are cooperating to track flu outbreaks in humans and animals, and to determine what types and strains of flu viruses are the causes.

To prevent another flu pandemic and reduce the numbers of flu epidemics, the National Institute of Allergy and Infectious Diseases (NIAID) supports research to find out how influenza viruses work, and to develop better vaccines to prevent and treat influenza virus infections.

For the first time, NIAID-supported researchers have built a flu virus from scratch. They made copies of a live influenza A virus by starting with its individual nucleic acid building blocks. Nucleic acids contain the virus's genetic blueprint. By allowing researchers to manipulate influenza viruses and produce mutations at will, the virus can be engineered to match exactly the strains that may be circulating in the coming season. This research has far-ranging implications for preventing flu and other infectious diseases, for gene therapy, and for understanding the ways flu strains mutate, spread, and cause widespread sickness and death.

Researchers supported by NIAID discovered why some influenza viruses are more deadly than others. They found an unusual molecular mechanism that amplifies the disease-causing power of influenza A virus. This mechanism could be a new marker for scientists to examine when attempting to predict the potential for a newly emergent influenza A virus to cause a pandemic.

In another research study, scientists supported by NIAID found that an investigational flu vaccine sprayed as a fine mist into children's nostrils is highly effective in preventing both the flu and otitis media, a common flu-related ear infection. If doctors give this vaccine to children routinely, the number of flu cases in children could decrease substantially. In addition, if the cases of ear infection with fever are reduced, children would have to take antibiotics less often.

A new NIAID program encourages private companies to get involved in influenza research. Through its Challenge Grants Program, NIAID gave matching funds to companies who were willing to commit their own dollars and resources toward developing new vaccines against several infectious diseases, including the flu.

In one of these studies, Aviron will try to develop a weakened live influenza virus vaccine and will study new ways to produce vaccines against future worldwide outbreaks (pandemics) of the flu. They will also work on a vaccine that can be given as a nasal mist instead of a shot, making it a promising option for widespread use.

Scientists at Aventis Pasteur hope to produce four new vaccines that will shorten the response time needed to produce vaccines against pandemic influenza viruses.

Currently, influenza vaccines are produced by growing the virus in chicken eggs. Egg proteins, however, cause allergic reactions in some people. Moreover, eggs may be in short supply during a pandemic. For these reasons, Novavax is studying ways to produce several influenza vaccines without growing them in eggs.

Where Can I Get More Information About the Flu?

* National Institute on Aging Information Center 1-800-222-2225

* (Centers for Disease Control and Prevention (CDC) National Immunization Information Program 1-800-232-2522

* Food and Drug Administration (FDA) HFI-40 Rockville, MD 20857 1-888-INFO-FDA (1-888-463-6332)

NIAID is a component of the National Institutes of Health (NIH). NIAID supports basic and applied research to prevent, diagnose, and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, tuberculosis, malaria, autoimmune disorders, asthma and allergies.

Prepared by: Office of Communications and Public Liaison National Institute of Allergy and Infectious Diseases National Institutes of Health Bethesda, MD 20892

Public Health Service U.S. Department of Health and Human Services December 2000
COPYRIGHT 2000 National Institute of Allergy and Infectious Diseases
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2000, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Chronic Fatigue Syndrome
Publication:Pamphlet by: National Institute of Allergy and Infectious Diseases
Article Type:Pamphlet
Date:Dec 1, 2000
Previous Article:Tuberculosis.
Next Article:Other Important STDS.

Related Articles
Chronic Fatigue Syndrome.
Questions and Answers About Fibromyalgia.
Recognizing and Understanding Chronic Fatigue Syndrome: Implications for Rehabilitation Counselors.
A vexing enigma: new insights confront chronic fatigue syndrome.

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters