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What is infectious mononucleosis (mono)?

Infectious mononucleosis (mono) is a disease caused by viruses.The most common cause is the Epstein-Barr virus (EBV). Mono is contagious, which means it can spread from person to person. It is common among teenagers and young adults, especially college students.

What causes infectious mononucleosis (mono)?

Mono can be caused by many different viruses. But it is most often caused by the Epstein-Barr virus (EBV). EBV is found all over the world. Most people get an EBV infection at some point in their lives, but only some of them will get the symptoms of mono. EBV infections often happen during childhood or when someone is a young adult. EBV infections in children usually do not cause symptoms. And when they do, it's hard to tell the difference between the symptoms of mono and the symptoms of other common childhood illnesses such as the flu. Teens and young adults who get EBV are more likely to have symptoms that are typical of mono.

EBV and the other viruses that cause mono are usually spread through body fluids, especially saliva (spit). This means that you can get it through kissing. That's why mono is sometimes called "the kissing disease." But you can also get these viruses if you share food, drinks, forks, spoons, or lip balm with someone who has mono. Other less common ways of getting an infection are through blood transfusions, organ transplants, and blood and semen during sexual contact.

What are the symptoms of infectious mononucleosis (mono)?

The symptoms of mono usually start four to six weeks after you get the infection. But they may start sooner in young children. The symptoms often develop slowly, and they may not all happen at the same time. They can include:

• Extreme fatigue
• Fever
• Sore throat
• Head and body aches
• Swollen lymph glands in your neck and armpits
• Rash
• Swollen liver, spleen, or both (these are less common symptoms)

Most people get better in two to four weeks. However, some people may feel fatigued for several more weeks. Occasionally, the symptoms can last for six months or longer.

How is infectious mononucleosis (mono) diagnosed?

Your healthcare provider may diagnose mono based on your symptoms and a physical exam. The exam will include checking to see if your lymph nodes, tonsils, liver, or spleen are swollen. In some cases, your provider might also order a mono test to confirm the diagnosis.

What are the treatments for infectious mononucleosis (mono)?

• Drinking plenty of fluids to avoid dehydration.
• Getting lots of rest.
• Taking over-the-counter medications for pain and fever. But don't give aspirin to children or teens because it may cause Reye syndrome. This syndrome is a rare, serious illness that can affect the brain and liver.

If you have severe symptoms, your provider may suggest additional treatment based on which organs in your body are affected by the mono.

Antibiotics don't treat viral infections, so they do not help with mono. Some people do get bacterial infections such as strep throat along with mono. In that case, you probably need antibiotics to treat the bacterial infection. But you should not take penicillin antibiotics like ampicillin or amoxicillin. Those antibiotics can cause a rash in people who have mono.

Mono can cause an enlarged spleen, which could rupture and cause a medical emergency. To try to protect the spleen, providers recommend avoiding intense exercise and contact sports until you fully recover (about a month).

Can infectious mononucleosis (mono) be prevented?

There is no vaccine to protect against mono. To lower your chance of getting or spreading mono:

• Don't share food, drinks, forks, spoons, or lip balm with anyone, especially if you or the other person has mono.
• Don't kiss someone if you or the other person has mono.
• Wash your hands often with soap and water.

Centers for Disease Control and Prevention

What is aplastic anemia?

Aplastic anemia is a rare but serious blood disorder. If you have it, your bone marrow doesn't make enough new blood cells. It happens when there is damage to stem cells inside your bone marrow. There are different types of aplastic anemia, including Fanconi anemia.

What causes aplastic anemia?

The causes of aplastic anemia can include:

• Autoimmune disorders, which are the most common cause
• Certain inherited gene changes, such as the one that can cause Fanconi anemia
• Toxic substances, such as pesticides, arsenic, and benzene
• Radiation therapy and chemotherapy for cancer
• Certain medicines
• Viral infections such as hepatitis, Epstein-Barr virus, or HIV
• Pregnancy

In many people, the cause is unknown. This is called idiopathic aplastic anemia.

What are the symptoms of aplastic anemia?

Aplastic anemia can develop suddenly or slowly. It can be mild or severe. The symptoms of aplastic anemia can include:

• Fatigue
• Weakness
• Dizziness
• Shortness of breath
• Easy bruising or bleeding

What other problems can aplastic anemia cause?

Aplastic anemia can cause other problems, including frequent infections and bleeding. It raises your risk of developing a serious blood disorder.

If not treated, aplastic anemia can also lead to heart problems such as an arrhythmia (a problem with the rate or rhythm of your heartbeat), an enlarged heart, or heart failure.

How is aplastic anemia diagnosed?

To find out if you have aplastic anemia, your doctor will:

• Take your medical and your family medical histories
• Do a physical exam
• Order tests, such as tests to check if you have low numbers of cells in your bone marrow and blood

What are the treatments for aplastic anemia?

If you have aplastic anemia, your doctor will create a treatment plan for you. The plan will be based on how severe the anemia is and what is causing it. Treatments can include:

• Blood transfusions
• Blood and marrow stem cell transplants
• Medicines to suppress your immune system

Because of the risk of blood disorders, your doctor will monitor your condition and screen you for blood disorders regularly.

NIH: National Heart, Lung, and Blood Institute

What is encephalitis?

Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.

What causes encephalitis?

There are different types of encephalitis, based on what the cause is. The two main types are infectious encephalitis and autoimmune encephalitis.

Infectious encephalitis is usually caused by a virus. In fact, viruses are the most common cause of encephalitis. Some of the different viruses that cause it include:

• Herpes viruses, including herpes simplex (HSV), the Epstein-Barr virus (which causes infectious mononucleosis) and the varicella-zoster virus (which causes chickenpox).
• Viruses you can get if you are bitten by an infected tick, such as tick-borne encephalitis (TBE virus) and Powassan virus.
• Viruses you can get if you are bitten by an infected mosquito, such as eastern equine encephalitis virus, West Nile virus, and La Crosse virus.
• Enteroviruses, which are a common group of viruses that mostly cause mild illness or respiratory infection. These infections usually happen in the summer and fall.

Bacteria, fungi, and parasites can also cause infectious encephalitis. But this is not common.

Autoimmune encephalitis happens when your immune system mistakenly attacks healthy brain cells. It can be triggered by conditions such as certain cancers, benign tumors, and infections. Sometimes the cause is not known.

Who is more likely to get encephalitis?

Anyone can get encephalitis, but you are more likely to get it if you:

• Have a weakened immune system, for example from having HIV or taking certain medicines. These could include medicines taken after an organ transplant, certain chemotherapy medicines, and specialized treatments for certain autoimmune diseases.
• Are a young child or older adult.
• Live in areas where there are ticks and mosquitoes that carry viruses that can cause encephalitis.

What are the symptoms of encephalitis?

The symptoms of encephalitis can vary a lot, depending on how severe it is. Many people do not have any symptoms. Others may have mild flu-like symptoms such as fever, fatigue, headache, or body aches. If encephalitis becomes more serious, it can cause:

• Severe headache
• Stiff neck
• Vomiting
• Seizures
• Behavior changes
• Drowsiness
• Muscle weakness
• Partial paralysis in your arms and legs
• Coma

Encephalitis can be dangerous in infants. Their symptoms may include:

• Fever
• Lethargy (weakness or drowsiness)
• Poor feeding
• Vomiting
• Body stiffness
• Unusual irritability or crying
• A full or bulging fontanel (the soft spot on the top of the head)

If you or your child is having symptoms of encephalitis, it's important to get medical care right away.

How is encephalitis diagnosed?

To find out if you have encephalitis, your health care provider:

• Will do a physical exam
• Will take your medical history, which includes asking about your symptoms
• May do a neurologic exam
• May order imaging tests, such as a brain CT scan or MRI
• May order an EEG (electroencephalography), which use small electric sensors to measure your brain activity
• May order blood and cerebrospinal fluid (CSF) tests

What are the treatments for encephalitis?

Most people with encephalitis will need treatment in the hospital. Depending on the cause, treatments may include antiviral medicines, antibiotics, corticosteroids, and other medicines.

For some types of encephalitis, there is no medicine to treat it. But rest, nutrition, and fluids can help your body fight the infection and relieve symptoms.

Some people may need physical, speech, and occupational therapy once the illness is under control.

Can encephalitis be prevented?

There are steps you can take to help prevent encephalitis that is caused by infections:

• Use good hygiene, including washing your hands often with soap and water.
• Don't share food, drinks, utensils, and glasses with other people.
• Get vaccines for viruses that can cause encephalitis.
• Avoid mosquito and tick bites, for example by:
  • Wearing insect repellent with DEET or another U.S. Environmental Protection Agency (EPA)-registered insect repellent. Make sure to follow the instructions for using the repellant.
  • Wearing clothes that cover your arms, legs and feet.
  • Treating your clothing and gear with products containing 0.5% permethrin before you go in grassy or woody areas.

NIH: National Institute of Neurological Disorders and Stroke

What is head and neck cancer?

Head and neck cancer is the name for cancers that develop in the mouth, nose and sinuses, salivary glands, and throat and voice box (larynx). Most head and neck cancers are squamous cell cancers. They begin in the moist tissues that line the head and neck. The cancer cells may spread into deeper tissue as the cancer grows.

There are other cancers that develop in the head and neck, such as brain cancer, eye cancer, and esophageal cancer. But they are usually not considered to be head and neck cancers, because those types of cancer and their treatments are different.

Who is more likely to develop head and neck cancer?

Anyone can get head and neck cancer, but you are more likely to develop it if you:

• Use tobacco or drink lots of alcohol. Your risk of developing head and neck cancer is even higher if you do both.
• Are male.
• Are over age 50.
• Have a history of head or neck cancer.
• Have HPV (for cancers in the tonsils and base of the tongue).
• Are exposed to wood dusts or certain other toxic substances at work (for upper throat, nose, and sinus cancers).
• Have had radiation exposure to the head and neck (for salivary gland cancer).
• Have Epstein-Barr virus (EBV) infection (for upper throat and salivary gland cancers).
• Are Asian (for upper throat cancer).

What are the symptoms of head and neck cancer?

The symptoms of head and neck cancer may include:

• A lump in the neck
• A sore in the mouth or the throat that does not heal and may be painful
• A sore throat that does not go away
• Trouble swallowing
• A change or hoarseness in the voice

Other possible symptoms can depend on the specific type of head and neck cancer.

How is head and neck cancer diagnosed?

Which exams and tests used to diagnose head and neck cancer can depend on the specific type of cancer. Possible exams and tests may include:

• A physical exam of the area that might have cancer.
• Blood and/or urine tests.
• An endoscopy.
• A biopsy or other procedure to collect cells from the area that might have cancer. The cells are viewed under a microscope to find out if they are abnormal.
• Imaging tests.

What are the treatments for head and neck cancer?

The treatment for head and neck cancer will depend on the specific type of cancer, the stage (how advanced the cancer is), your overall health, and other factors. The treatment options might include:

• Surgery
• Radiation therapy
• Chemotherapy
• Cancer immunotherapy
• Targeted therapy, which uses drugs or other substances that mainly attack specific cancer cells and cause less harm to normal cells

In some cases, you may need a combination of treatments. Sometimes surgery can affect how well you can chew, swallow, or talk. Rehabilitation, such as physical therapy, dietary counseling, and speech therapy, may help.

Can head and neck cancer be prevented?

There are steps you can take to help prevent head and neck cancer:

• Not smoking
• Limiting alcohol use or not drinking at all
• Getting regular dental exams
• Talking to your provider about HPV vaccination

NIH: National Cancer Institute

What is Hodgkin lymphoma?

Hodgkin lymphoma, also called Hodgkin disease, is a type of cancer that develops in the lymph system. Your lymph system is part of your immune system. It helps protect your body from infection and disease.

The lymph system is made up of tissues and organs that produce, store, and carry white blood cells. It includes your:

• Bone marrow
• Lymph nodes
• Lymphatic vessels
• Spleen
• Thymus
• Tonsils

Hodgkin lymphoma is one of the main types of lymphoma. The other is non-Hodgkin lymphoma. Each type starts in different types of white blood cells.

What causes Hodgkin lymphoma?

The cause of Hodgkin lymphoma is unknown. But there are certain people who are at higher risk of developing it.

Who is more likely to develop Hodgkin lymphoma?

Certain factors can make you more likely to develop Hodgkin lymphoma:

• Age. Hodgkin lymphoma is most common in early adulthood (age 20-39 years) and in late adulthood (age 65 years and older).
• Being male. The risk of adult Hodgkin lymphoma is slightly higher in males than in females.
• Past Epstein-Barr virus (EBV) infection. Having an infection with EBV as a young child or teenager increases your risk of Hodgkin lymphoma.
• A family history of Hodgkin lymphoma. Having a parent or sibling with Hodgkin lymphoma increases your risk of developing it.

What are the symptoms of Hodgkin lymphoma?

The signs and symptoms of Hodgkin lymphoma may include:

• Painless, swollen lymph nodes in the neck, underarm, or groin
• Fever for no known reason
• Drenching night sweats (very heavy sweating during sleep)
• Weight loss for no known reason in the past 6 months
• Itchy skin, especially after bathing or drinking alcohol
• Fatigue

How is Hodgkin lymphoma diagnosed?

To find out if you have Hodgkin lymphoma, your provider:

• Will ask about your symptoms and medical history. This will include checking for signs of disease, such as lumps or anything else that seems unusual.
• May order some lab tests, such as:
  • Complete blood count
  • Blood chemistry studies
  • Lactate dehydrogenase (LDH) test
  • Erythrocyte sedimentation rate (ESR) test
  • Blood tests to rule out other medical conditions
  • May do imaging tests such as a CT and PET (positron emission tomography) scans
  • May do a lymph node biopsy

What are the treatments for Hodgkin lymphoma?

Treatments for Hodgkin lymphoma include:

• Chemotherapy
• Radiation therapy
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells
• Cancer immunotherapy

Hodgkin lymphoma can usually be cured if it is found and treated early.

NIH: National Cancer Institute

What is the immune system?

Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.

When germs such as bacteria or viruses invade your body, they attack and multiply. This is called an infection. The infection causes the disease that makes you sick. Your immune system protects you from the disease by fighting off the germs.

What are the parts of the immune system?

The immune system has many different parts, including:

• Your skin, which can help prevent germs from getting into the body
• Mucous membranes, which are the moist, inner linings of some organs and body cavities. They make mucus and other substances which can trap and fight germs.
• White blood cells, which fight germs
• Organs and tissues of the lymph system, such as the thymus, spleen, tonsils, lymph nodes, lymph vessels, and bone marrow. They produce, store, and carry white blood cells.

How does the immune system work?

Your immune system defends your body against substances it sees as harmful or foreign. These substances are called antigens. They may be germs such as bacteria and viruses. They might be chemicals or toxins. They could also be cells that are damaged from things like cancer or sunburn.

When your immune system recognizes an antigen, it attacks it. This is called an immune response. Part of this response is to make antibodies. Antibodies are proteins that work to attack, weaken, and destroy antigens. Your body also makes other cells to fight the antigen.

Afterwards, your immune system remembers the antigen. If it sees the antigen again, it can recognize it. It will quickly send out the right antibodies, so in most cases, you don't get sick. This protection against a certain disease is called immunity.

What are the types of immunity?

There are three different types of immunity:

• Innate immunity is the protection that you are born with. It is your body's first line of defense. It includes barriers such as the skin and mucous membranes. They keep harmful substances from entering the body. It also includes some cells and chemicals which can attack foreign substances.
• Active immunity, also called adaptive immunity, develops when you are infected with or vaccinated against a foreign substance. Active immunity is usually long-lasting. For many diseases, it can last your entire life.
• Passive immunity happens when you receive antibodies to a disease instead of making them through your own immune system. For example, newborn babies have antibodies from their mothers. People can also get passive immunity through blood products that contain antibodies. This kind of immunity gives you protection right away. But it only lasts a few weeks or months.

What can go wrong with the immune system?

Sometimes a person may have an immune response even though there is no real threat. This can lead to problems such as allergies, asthma, and autoimmune diseases. If you have an autoimmune disease, your immune system attacks healthy cells in your body by mistake.

Other immune system problems happen when your immune system does not work correctly. These problems include immunodeficiency diseases. If you have an immunodeficiency disease, you get sick more often. Your infections may last longer and can be more serious and harder to treat. They are often genetic disorders.

There are other diseases that can affect your immune system. For example, HIV is a virus that harms your immune system by destroying your white blood cells. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). People with AIDS have badly damaged immune systems. They get an increasing number of severe illnesses.