Flu

What is the flu?

The flu, also called influenza, is a respiratory infection caused by viruses. Each year, millions of Americans get sick with the flu. Sometimes it causes mild illness. But it can also be serious or even deadly, especially for people over 65, newborn babies, and people with certain chronic illnesses.

What causes the flu?

The flu is caused by flu viruses that spread from person to person. When someone with the flu coughs, sneezes, or talks, they spray tiny droplets. These droplets can land in the mouths or noses of people who are nearby. Less often, a person may get flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose, or possibly their eyes.

What are the symptoms of the flu?

Symptoms of the flu come on suddenly and may include:

• Fever or feeling feverish/chills
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue (tiredness)

Some people may also have vomiting and diarrhea. This is more common in children.

Sometimes people have trouble figuring out whether they have a cold or the flu. There are differences between them:

Signs and SymptomsColdFluStart of symptomsSlowlySuddenlyFeverRarelyUsuallyAchesSometimes (slight)UsuallyFatigue, weaknessSometimesUsuallyHeadacheRarelyCommonStuffy nose, sneezing, or sore throatCommonSometimes

Sometimes people say that they have a "flu" when they really have something else. For example, "stomach flu" isn't the flu; it's gastroenteritis.

What other problems can the flu cause?

Some people who get the flu will develop complications. Some of these complications can be serious or even life-threatening. They include:

• Bronchitis
• Ear infection
• Sinus infection
• Pneumonia
• Inflammation of the heart (myocarditis), brain (encephalitis), or muscle tissues (myositis, rhabdomyolysis)

The flu also can make chronic health problems worse. For example, people with asthma may have asthma attacks while they have flu.

Certain people are more likely to have complications from the flu, including:

• Adults 65 and older
• Pregnant women
• Children younger than 5
• People with certain chronic health conditions, such as asthma, diabetes, and heart disease

How is the flu diagnosed?

To diagnose the flu, health care providers will first do a medical history and ask about your symptoms. There are several tests for the flu. For the tests, your provider will swipe the inside of your nose or the back of your throat with a swab. Then the swab will be tested for the flu virus.

Some tests are quick and give results in 15-20 minutes. But these tests are not as accurate as other flu tests. These other tests can give you the results in one hour or several hours.

What are the treatments for the flu?

Most people with the flu recover on their own without medical care. People with mild cases of the flu should stay home and avoid contact with others, except to get medical care.

But if you have symptoms of flu and are in a high risk group or are very sick or worried about your illness, contact your health care provider. You might need antiviral medicines to treat your flu. Antiviral medicines can make the illness milder and shorten the time you are sick. They also can prevent serious flu complications. They usually work best when you start taking them within 2 days of getting sick.

Can the flu be prevented?

The best way to prevent the flu is to get a flu vaccine every year. But it's also important to have good health habits like covering your cough and washing your hands often. This can help stop the spread of germs and prevent the flu.

Centers for Disease Control and Prevention

H1N1 Flu (Swine Flu)

Swine flu is an infection caused by a virus. It's named for a virus that pigs can get. People do not normally get swine flu, but human infections can and do happen. In 2009 a strain of swine flu called H1N1 infected many people around the world.

The virus is contagious and can spread from human to human. Symptoms of swine flu in people are similar to the symptoms of regular human flu and include fever, cough, sore throat, body aches, headache, chills and fatigue.

There are antiviral medicines you can take to prevent or treat swine flu. There is a vaccine available to protect against swine flu. You can help prevent the spread of germs that cause respiratory illnesses like influenza by:

• Covering your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Washing your hands often with soap and water, especially after you cough or sneeze. You can also use alcohol-based hand cleaners.
• Avoiding touching your eyes, nose or mouth. Germs spread this way.
• Trying to avoid close contact with sick people.
• Staying home from work or school if you are sick.

Centers for Disease Control and Prevention

Bird Flu

What is bird flu?

Birds, just like people, can get the flu. Another name for bird flu is avian influenza. The viruses that cause bird flu normally only infect birds, including chickens, other poultry, and wild birds such as ducks. But sometimes the viruses can infect other animals and, in rare cases, people.

A few types of these viruses have caused most of the infections in people. They are the H5N1, H7N9, and H5N6 viruses. These infections in people have mainly been in Asia, Africa, Europe, the Pacific, and the Near East. Although it's very rare, there have also been some infections in people in the United States.

How do you get bird flu?

The most common ways you can get bird flu are from:

• Touching your eyes, nose, or mouth after handling infected live or dead birds
• Touching surfaces or handling items contaminated by bird flu viruses and then touching your eyes, nose, or mouth
• Breathing in droplets or dust contaminated with the virus

It's also possible (but very rare) to get bird flu from:

• Another type of animal who has bird flu. Bird flu can also infect many other animals, including some dogs, cats, certain wild and zoo animals, and livestock such as cattle. These animals can then spread the flu to people.
• Another person.
• Eating poultry, eggs, and beef that were not properly handled and cooked.
• Drinking raw milk.

Who is more likely to get bird flu?

Certain people may be more likely to get bird flu, including:

• Poultry workers
• Animal handlers
• Wildlife biologists
• Disease control workers
• Research laboratory workers
• Veterinarians
• People who travel to countries where bird flu is present

What are the symptoms of bird flu in humans?

Sometimes bird flu doesn't cause any symptoms. But if you do feel sick, your symptoms can range from mild to severe. Often, the symptoms are similar to the (seasonal) flu, such as:

• Fever (but not everyone has a fever)
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Fatigue
• Headaches
• Eye redness (conjunctivitis)
• Trouble breathing
• Diarrhea

People with severe illness from bird flu may have pneumonia and might need to be hospitalized.

How is bird flu diagnosed?

Laboratory testing is used to diagnose bird flu. It's usually done with a nasal or throat swab. This testing is more accurate when the swab is collected during the first few days of illness.

For people who are severely ill, health care providers may do testing of a different sample, such as fluid taken during a bronchoalveolar lavage or other procedure.

What are the treatments for bird flu?

Bird flu is treated with antiviral medicines. It's important to get them as soon as possible. The medicines may make your illness less severe.

You may also be given antiviral medicines if you were exposed to a person or animal who has the virus. This may help prevent you from getting sick.

Can bird flu be prevented?

There is currently no vaccine available to the public. The government has developed a virus that is similar to some H5N1 viruses. The virus could be used to produce a vaccine for people, if needed.

It's important to take precautions to prevent bird flu:

• If you have a job or pastime that puts you in contact with birds or other animals, make sure to use proper protective equipment.
• Otherwise try to avoid direct contact with wild birds and other animals.
• Wash your hands with soap and water after touching birds or other animals.
• Since it's possible to get bird flu through some foods, make sure to handle and cook your food safely and avoid raw milk.

Centers for Disease Control and Prevention

Flu Shot

What is the flu?

The flu (influenza) is a respiratory infection. It is caused by influenza viruses that infect your nose, throat, and lungs. These viruses can spread from person to person.

Most people with the flu get better on their own, without medical care. But for some people, the flu is serious. It can cause complications and sometimes even death. People who are 65 and older, under age 5, pregnant, or have certain health conditions are at higher risk of flu complications.

Getting vaccinated against the flu each year is best way to lower your risk of the flu and its complications.

What are the benefits of getting a flu shot?

There are many reasons to get a flu shot each year:

• It may keep you from getting sick with the flu.
• If you do get the flu, it may be less severe. You may also be less likely to have complications or need to be hospitalized with the flu.
• If you have certain chronic health conditions, getting a flu shot may help prevent the flu from making your condition worse. For example, if you have COPD or diabetes, the flu can worsen your condition so much that you might need to be hospitalized. Getting a flu shot can lower this risk.
• Getting the vaccine during pregnancy not only helps protect you from the flu during and after pregnancy. It also helps protect your baby from flu during their first few months of life.
• It has been shown to lower the risk of severe life-threatening flu in children.
• It may also protect the people around you, including those who are at higher risk of complications.

How do flu shots work?

The flu vaccine causes your immune system to make antibodies about two weeks after you get the shot. These antibodies provide protection against infection with the flu viruses that are in the vaccine.

Who needs a flu shot?

The U.S Centers for Disease Control and Prevention (CDC) recommends annual flu shots for everyone 6 months and older, with a few rare exceptions.

Flu shots are especially important for people who are at high risk of developing serious complications from the flu.

There are different types of flu vaccines. There are injectable vaccines (shots) and nasal spray vaccines. There are also some vaccines especially for people 65 and older. Ask your health care provider which one is right for you.

Who should not get a flu shot?

There are some people who should not get a flu shot:

• Children younger than 6 months of age.
• Have severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine. This might include gelatin, antibiotics, or other ingredients.

Some people need to talk to their provider before they get a flu shot. They include people who:

• Have an allergy to any of the ingredients in the vaccine.
• Have ever had Guillain-Barre syndrome(GBS). Some people with a history of GBS should not get a flu vaccine.

If you are moderately or severely ill, you usually need to wait until you recover before getting a flu shot.

Why do I need a flu shot every year?

You need to get a flu shot every year because:

• Your immune protection from the vaccine declines over time. You need to get the shot every year to boost that protection.
• Flu viruses are constantly changing, so every year, the flu vaccine is updated. The flu vaccine will include protection against the viruses that will most likely be common during the upcoming flu season.

When should I get the flu shot?

For most people who need only one dose of the flu vaccine for the season, September and October are usually good times to get it. It's best to be vaccinated by the end of October.

Some children need two doses of the flu vaccine. They should get their first dose as soon as the vaccine is available. They need to get the second dose at least four weeks after the first.

If you are pregnant, talk to your provider about when to get the vaccine. When you should get it can vary, based on how far along you are in your pregnancy.

Do flu shots cause side effects?

Flu vaccines have been shown to be safe. But like any medical product, they can cause side effects. If you have any side effects, they are usually mild and go away on their own within a few days. Common side effects include:

• Soreness, redness, and/or swelling from the shot
• Headache
• Fever
• Nausea
• Muscle aches

The flu shot, like other injections, can occasionally cause fainting. In rare cases, some people have a serious allergic reaction.

Centers for Disease Control and Prevention

Gastroenteritis

What is gastroenteritis?

Gastroenteritis is an inflammation of the lining of the stomach and intestines. The main symptoms include vomiting and diarrhea. It is usually not serious in healthy people, but it can sometimes lead to dehydration or cause severe symptoms.

What causes gastroenteritis?

There can be many different causes of gastroenteritis:

• Viruses
• Bacteria
• Parasites
• Chemicals
• Reactions to certain medicines and food

Viral gastroenteritis is the most common type. It can be caused by many different viruses, including noroviruses and rotaviruses. Some people call viral gastroenteritis the "stomach flu." But this name is not medically correct. It is not caused by flu viruses. The flu is a respiratory infection that affects your nose, throat and lungs.

When gastroenteritis is caused by consuming foods or drinks contaminated with viruses, bacteria, parasites, or chemicals, this is called food poisoning.

The viruses, bacteria, and parasites that cause gastroenteritis can also spread from person to person. You could be infected when you touch something that has the germs on it and then touch your eyes, mouth, or nose.

What are the symptoms of gastroenteritis?

The symptoms of gastroenteritis include:

• Diarrhea
• Pain or cramping in your abdomen (belly)
• Nausea
• Vomiting
• Sometimes fever

Gastroenteritis is usually not serious. But it can sometimes cause lead to dehydration or cause severe symptoms. Certain people are at higher risk for these problems. They include:

• Pregnant women
• Older adults
• People with weakened immune systems or other serious health conditions
• Infants
• Babies who were born prematurely or have other health conditions

If you or a family member are at higher risk and have symptoms of gastroenteritis, contact a health care provider right away. Even if you are not at high risk, it is possible to become dehydrated or have more serious symptoms. There are some warning signs to watch for. It's important to contact a provider right away if you or your child have any of them:

• For adults, they include:
  • Change in mental state, such as irritability or lack of energy
  • Diarrhea lasting more than 2 days
  • High fever
  • Vomiting often
  • Six or more loose stools in a day
  • Severe pain in the abdomen (belly) or rectum
  • Stools that are black and tarry or contain blood or pus
  • Symptoms of dehydration, such as thirst, dry mouth, headache, dark-colored urine, and urinating less than normal
• For infants and children, they include:
  • Change in the child's mental state, such as irritability or lack of energy
  • Diarrhea lasting more than a day
  • Any fever in infants
  • High fever in older children
  • Frequent loose stools
  • Vomiting often
  • Severe pain in the abdomen (belly) or rectum
  • Signs or symptoms of dehydration, such as thirst, dry mouth, urinating less than usual or no wet diapers for 3 hours or more, and no tears when crying
  • Stools that are black and tarry or contain blood or pus

How is gastroenteritis diagnosed?

To find out if you have gastroenteritis, your provider:

• Will do a physical exam
• Will ask about your symptoms
• May do tests of your stool

What are the treatments for gastroenteritis?

Usually, people with gastroenteritis get better on their own, with rest and plenty of fluids and electrolytes. Your provider may suggest that you take a probiotic. Studies suggest that some probiotics may help shorten a case of diarrhea.

People with more severe symptoms may need medicines to control nausea or vomiting. Providers may also give other medicines for certain types of gastroenteritis, such as antibiotics for some bacterial types and antiparasitic medicines for some parasitic types.

Can gastroenteritis be prevented?

Gastroenteritis cannot always be prevented. But proper hand washing, cleaning surfaces that may be infected with germs, and safe food preparation may help prevent some of the infections that can cause gastroenteritis. There are vaccines for infants to protect against rotavirus infections.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases