We are in the process of updating our AvaFlu website and have included information below about flu and colds from the National Institutes of Health  

• Information About The Flu

• Information About The Common Cold

Flu

OVERVIEW

Influenza, or 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 Centers for Disease Control and Prevention (CDC) estimates that 5 to 20 percent of 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 than 200,000 people are hospitalized and about 36,000 people die from the flu and its complications every year.

Flu outbreaks

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 3 weeks and subsides after another 3 or 4 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.

Importance of flu

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.

Types of flu viruses

The first flu virus was identified in the 1930s. Since then, scientists have classified influenza 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.

TRANSMISSION

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 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.

SYMPTOMS

If you get infected by the flu virus, you will usually feel symptoms 1 to 4 days later. You can spread the flu to others before your symptoms start and for another 3 to 4 days after your symptoms appear. The symptoms start very quickly and may include

• Body aches
• Chills
• Dry cough
• Fever
• Headache
• Sore throat
• Stuffy nose

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 call "stomach flu" is not influenza.

DIAGNOSIS

Usually, health care providers diagnose the flu on the basis of whether it is epidemic in the community and whether the person's complaints fit the current pattern of symptoms. Health care providers 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.

PREVENTION

Flu Vaccine

The main way to keep from getting 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 workplaces, 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 have been killed, they cannot cause infection. 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 doctor's offices 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 will still give you some protection.

Until recently, you could get the flu vaccine only as an injection (shot). In 2003, however, the Food and Drug Administration (FDA) approved a nasal spray flu vaccine called FluMist that you can get from your health care provider. The FDA approved it for use in healthy people aged 5 to 49 years.

You should not use FluMist if

• You have certain lung conditions, including asthma, or heart conditions
• You have metabolic disorders such as diabetes or kidney dysfunction
• You have an immunodeficiency disease or are on immunosuppressive treatment
• You have had Guillain-Barré syndrome
• You are pregnant
• You have a history of allergy or hypersensitivity, including anaphylaxis, to any of the parts of FluMist or to eggs

Children or teenagers who regularly take aspirin or products containing aspirin also should not take FluMist.

Your immune system takes time to respond to the flu vaccine. Therefore, you should get vaccinated 6 to 8 weeks before flu season begins in November to prevent getting infected or reduce the severity of flu if you do get it. Because the flu season usually lasts until March, however, it's not too late to get it after the season has begun. 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.

Possible side effects

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 12 hours after vaccination and may last for up to 2 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 health care provider before getting vaccinated.

Vaccine recommendations

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 form of anemia
• You will be more than 3 months pregnant during the flu season
• You live in a nursing home or other chronic-care housing facility
• You are in close contact with children 0 to 23 months of age

CDC recommends that children 6 months to 23 months of age get the flu vaccine.

Children and teenagers (6 months to 18 years of age) 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 providers and volunteers should get the flu vaccine if they work with people in any of the above groups.

Medicine for Prevention

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

• Tamiflu (oseltamivir)
• Flumadine (rimantadine)
• Symmetrel (amantadine)
• Relenza (zanamivir)

Tamiflu, Flumadine, and Symmetrel may be used by children who are 1 year of age and older and adults. For adults and children 5 years of age and older, Relenza is used for prevention of flu.

• These medicines help prevent the flu if you take them for at least 2 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 them immediately following flu vaccination during a flu epidemic to protect you during the 2- to 4-week period before antibodies develop or when a flu epidemic is caused by virus strains other than those covered by the vaccine. (Antibodies are proteins from your immune system that protect you from the flu virus.)

Your health care provider can help you decide which medicine is best for you. You should discuss the flu vaccine and medicines with your health care provider before the flu season begins.

TREATMENT

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

• Tamiflu (oseltamivir) is for treating influenza A and B virus infections in adults and children 1 year and older.
• Relenza (zanamivir) is for treating influenza A and B virus infections in children 7 years and older and adults who have an uncomplicated flu infection and who have had symptoms for no more than 2 days. Relenza is not used to prevent flu infection.
• Flumadine (rimantadine) is for treating adults who have influenza type A virus infections. It has no effect on influenza type B virus infections.
• Symmetrel (amantadine) is for treating adults and children who are 1 year of age and older to prevent and treat type A influenza virus infections but has no effect on influenza B virus infections. Symmetrel, however, is more likely to cause side effects such as lightheadedness and inability to sleep more often than is Flumadine.

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 more quickly return to your daily routine.

COMPLICATIONS

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

Complications usually appear after you start feeling better. After a brief period of improvement, you may suddenly get these symptoms

• 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 health care provider immediately to get the appropriate treatment.

Flu complications in children and teenagers

Reye's syndrome, a condition that affects the nerves, sometimes develops in children and teenagers 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 health care provider before giving aspirin or products that contain aspirin to children. Acetaminophen does not seem to be connected with Reye's syndrome.

Other complications of the flu that can 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.

IMPORTANT FLU OUTBREAKS SINCE 1918

If a flu virus emerges that is either new or 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 influenza virus called H5N1. 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.

In 1999, two children in Hong Kong were infected with an influenza virus called H9N2 that usually infects birds. They were the first confirmed human infections by this virus, and both children recovered. Although other infections from this virus were reported from China, there have been no cases since April 1999.

In 2003, one flu strain, labeled H5N1, caused two Hong Kong family members to be hospitalized after a visit to China, killing one of them, a 33-year-old man. (A third family member died while in China of an undiagnosed respiratory illness.)

As of November 29, 2005, H5N1 has caused illness in 133 people, 68 of whom have died. H5N1 infections have been confirmed in Thailand, Vietnam, Indonesia, Cambodia, and China. Researchers are especially concerned because this flu strain, which is transmitted by birds and is quite deadly, is becoming endemic in Asia and has infected humans in an unprecedented number of countries.

In addition, from 2003 to the present, several other strains of bird flu have caused illness in Egypt, Canada, and the Netherlands.

RESEARCH

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

Although flu epidemics pop up in the fall and winter seasons in communities throughout the world every year, there has not been a pandemic since 1968. Scientists are worried that a new flu virus will emerge in this 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.

The Common Cold

OVERVIEW

Sneezing, scratchy throat, runny nose-everyone knows the first signs of a cold, probably the most common illness known. Although the common cold is usually mild, with symptoms lasting 1 to 2 weeks, it is a leading cause of doctor visits and missed days from school and work. According to the Centers for Disease Control and Prevention, 22 million school days are lost annually in the United States due to the common cold.

In the course of a year, people in the United States suffer 1 billion colds, according to some estimates.

Children have about 6 to 10 colds a year. One important reason why colds are so common in children is because they are often in close contact with each other in daycare centers and schools. In families with children in school, the number of colds per child can be as high as 12 a year. Adults average about 2 to 4 colds a year, although the range varies widely. Women, especially those aged 20 to 30 years, have more colds than men, possibly because of their closer contact with children. On average, people older than 60 have fewer than one cold a year.

CAUSES

The Viruses

More than 200 different viruses are known to cause the symptoms of the common cold. Some, such as the rhinoviruses, seldom produce serious illnesses. Others, such as parainfluenza and respiratory syncytial virus, produce mild infections in adults but can precipitate severe lower respiratory infections in young children.

Rhinoviruses (from the Greek rhin, meaning "nose") cause an estimated 30 to 35 percent of all adult colds, and are most active in early fall, spring, and summer. More than 110 distinct rhinovirus types have been identified. These agents grow best at temperatures of about 91 degrees Fahrenheit, the temperature inside the human nose.

Scientists think coronaviruses cause a large percentage of all adult colds. They bring on colds primarily in the winter and early spring. Of the more than 30 kinds, three or four infect humans. The importance of coronaviruses as a cause of colds is hard to assess because, unlike rhinoviruses, they are difficult to grow in the laboratory.

Approximately 10 to 15 percent of adult colds are caused by viruses also responsible for other, more severe illnesses: adenoviruses, coxsackieviruses, echoviruses, orthomyxoviruses (including influenza A and B viruses, which cause flu), paramyxoviruses (including several parainfluenza viruses), respiratory syncytial virus, and enteroviruses.

The causes of 30 to 50 percent of adult colds, presumed to be viral, remain unidentified. The same viruses that produce colds in adults appear to cause colds in children. The relative importance of various viruses in pediatric colds, however, is unclear because it's difficult to isolate the precise cause of symptoms in studies of children with colds.

The weather

There is no evidence that you can get a cold from exposure to cold weather or from getting chilled or overheated.

Other factors

There is also no evidence that your chances of getting a cold are related to factors such as exercise, diet, or enlarged tonsils or adenoids. On the other hand, research suggests that psychological stress and allergic diseases affecting your nose or throat may have an impact on your chances of getting infected by cold viruses.

THE COLD SEASON

In the United States, most colds occur during the fall and winter. Beginning in late August or early September, the rate of colds increases slowly for a few weeks and remains high until March or April, when it declines. The seasonal variation may relate to the opening of schools and to cold weather, which prompt people to spend more time indoors and increase the chances that viruses will spread to you from someone else.

Seasonal changes in relative humidity also may affect the prevalence of colds. The most common cold-causing viruses survive better when humidity is low-the colder months of the year. Cold weather also may make the inside lining of your nose drier and more vulnerable to viral infection.

SYMPTOMS

Symptoms of the common cold usually begin 2 to 3 days after infection and often include

• Mucus buildup in your nose
• Difficulty breathing through your nose
• Swelling of your sinuses
• Sneezing
• Sore throat
• Cough
• Headache

Fever is usually slight but can climb to 102 degrees Fahrenheit in infants and young children. Cold symptoms can last from 2 to 14 days, but like most people, you'll probably recover in a week. If symptoms occur often or last much longer than 2 weeks, you might have an allergy rather than a cold.

Colds occasionally can lead to bacterial infections of your middle ear or sinuses, requiring treatment with antibiotics. High fever, significantly swollen glands, severe sinus pain, and a cough that produces mucus, may indicate a complication or more serious illness requiring a visit to your healthcare provider.

TRANSMISSION

You can get infected by cold viruses by either of these methods.

• Touching your skin or environmental surfaces, such as telephones and stair rails, that have cold germs on them and then touching your eyes or nose
• Inhaling drops of mucus full of cold germs from the air

TREATMENT

There is no cure for the common cold, but you can get relief from your cold symptoms by

• Resting in bed
• Drinking plenty of fluids
• Gargling with warm salt water or using throat sprays or lozenges for a scratchy or sore throat
• Using petroleum jelly for a raw nose
• Taking aspirin or acetaminophen, Tylenol, for example, for headache or fever

A word of caution: Several studies have linked aspirin use to the development of Reye's syndrome in children recovering from flu or chickenpox. Reye's syndrome is a rare but serious illness that usually occurs in children between the ages of 3 and 12 years. It can affect all organs of the body but most often the brain and liver. While most children who survive an episode of Reye's syndrome do not suffer any lasting consequences, the illness can lead to permanent brain damage or death. The American Academy of Pediatrics recommends children and teenagers not be given aspirin or medicine containing aspirin when they have any viral illness such as the common cold.

Over-the-counter cold medicines

Nonprescription cold remedies, including decongestants and cough suppressants, may relieve some of your cold symptoms but will not prevent or even shorten the length of your cold. Moreover, because most of these medicines have some side effects, such as drowsiness, dizziness, insomnia, or upset stomach, you should take them with care.

Over-the counter-antihistamines

Nonprescription antihistamines may give you some relief from symptoms such as runny nose and watery eyes which are commonly associated with colds.

Antibiotics

Never take antibiotics to treat a cold because antibiotics do not kill viruses. You should use these prescription medicines only if you have a rare bacterial complication, such as sinusitis or ear infections. In addition, you should not use antibiotics "just in case" because they will not prevent bacterial infections.

Steam

Although inhaling steam may temporarily relieve symptoms of congestion, health experts have found that this approach is not an effective treatment.

PREVENTION

There are several ways you can keep yourself from getting a cold or passing one on to others.

• Because cold germs on your hands can easily enter through your eyes and nose, keep your hands away from those areas of your body
• If possible, avoid being close to people who have colds
• If you have a cold, avoid being close to people
• If you sneeze or cough, cover your nose or mouth.

Handwashing

Handwashing with soap and water is the simplest and one of the most effective ways to keep from getting colds or giving them to others. During cold season, you should wash your hands often and teach your children to do the same. When water isn't available, CDC recommends using alcohol-based products made for washing hands.

Disinfecting

Rhinoviruses can live up to 3 hours on your skin. They also can survive up to 3 hours on objects such as telephones and stair railings. Cleaning environmental surfaces with a virus-killing disinfectant might help prevent spread of infection.

Vaccine

Because so many different viruses can cause the common cold, the outlook for developing a vaccine that will prevent transmission of all of them is dim. Scientists, however, continue to search for a solution to this problem.

Unproven prevention methods

Echinacea

Echinacea is a dietary herbal supplement that some people use to treat their colds. Researchers, however, have found that while the herb may help treat your colds if taken in the early stages, it will not help prevent them.

One research study funded by the National Center for Complementary and Alternative Medicine, a part of the National Institutes of Health, found that echinacea is not affective at all in treating children aged 2 to 11.

Vitamin C

Many people are convinced that taking large quantities of vitamin C will prevent colds or relieve symptoms. To test this theory, several large-scale, controlled studies involving children and adults have been conducted. To date, no conclusive data has shown that large doses of vitamin C prevent colds. The vitamin may reduce the severity or duration of symptoms, but there is no clear evidence.

Taking vitamin C over long periods of time in large amounts may be harmful. Too much vitamin C can cause severe diarrhea, a particular danger for elderly people and small children.

RESEARCH

Thanks to basic research, scientists know more about the rhinovirus than almost any other virus, and have powerful new tools for developing antiviral drugs. Although the common cold may never be uncommon, further investigations offer the hope of reducing the huge burden of this universal problem.

Research on rhinovirus transmission

Much of the research on the transmission of the common cold has been done with rhinoviruses, which are shed in the highest concentration in nasal secretions. Studies suggest a person is most likely to transmit rhinoviruses in the second to fourth day of infection, when the amount of virus in nasal secretions is highest.

Researchers also have shown that using aspirin to treat colds increases the amount of virus in nasal secretions, possibly making the cold sufferer more of a hazard to others.

Statements made on this site have not been evaluated by the United States Food and Drug Administration and are for informational purposes only and is not intended as a substitute for advice from your physician or other health care professional. This product is not intended to diagnose, treat, cure or prevent disease. AvaFlu is a trademark of Boulder Natural Labs, LLC.