Diseases & Conditions

Showing results filtered by:

Asthma is a chronic lung disease that intermittently inflames and narrows the airways. People with asthma may experience wheezing, breathlessness, chest tightness, and coughing when the airways narrow.

More than 80 diseases occur as a result of the immune system attacking the body’s own organs, tissues, and cells. Some of the more common autoimmune diseases include type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and inflammatory bowel disease.

Although the causes of many autoimmune diseases remain unknown, a person’s genes in combination with infections and other environmental exposures are likely to play a significant role in disease development. Treatments are available for many autoimmune diseases, but cures have yet to be discovered.

Autoimmune lymphoproliferative syndrome (ALPS) is a rare genetic disorder of the immune system that affects both children and adults. In ALPS, unusually high numbers of white blood cells called lymphocytes accumulate in the lymph nodes, liver, and spleen, which can lead to enlargement of these organs. ALPS can cause numerous autoimmune problems such as anemia (low count of red blood cells), thrombocytopenia (low count of platelets), and neutropenia (low count of neutrophils, the most common type of white blood cell in humans).

APS-1 is a genetic immune disorder that causes a diverse range of symptoms, including autoimmunity against different types of organs and an increased susceptibility to candidiasis, a fungal infection caused by Candida yeast.

APS-1 has other names, including autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED); autoimmune polyendocrinopathy, type 1; and polyglandular autoimmune (PGA) syndrome, type 1.

CARD9 deficiency is a genetic immune disorder that results in susceptibility to fungal infections like candidiasis, which is caused by the yeast fungus Candida. Typically, Candida and other fungi are present on the skin and mucosal surfaces, like the mouth, and do not cause severe problems in healthy people. However, people with deficient immune systems are more vulnerable to symptomatic infection.

Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. An estimated 3-5 million cases and over 100,000 deaths occur each year around the world. The infection is often mild or without symptoms, but can sometimes be severe. Approximately one in 10 (5 to 10 percent) infected persons will have severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these people, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Chronic granulomatous disease (CGD) is a genetic disorder in which white blood cells called phagocytes are unable to kill certain bacteria and fungi. People with CGD have increased susceptibility to infections caused by certain types of bacteria and fungi, such as Staphylococcus aureus, Serratia marcescens, Burkholderia cepacia, Nocardia species, and Aspergillus species.

Common variable immunodeficiency (CVID) is characterized by low levels of antibodies and an increased risk of infections. Although the disease usually is diagnosed in adults, it also can occur in children. CVID also is known as hypogammaglobulinemia, adult-onset agammaglobulinemia, late-onset hypogammaglobulinemia, and acquired agammaglobulinemia.

Congenital neutropenia syndromes are a group of disorders characterized by low levels of neutrophils—white blood cells necessary for combating infections—present from birth. Congenital neutropenia syndromes also may be called congenital agranulocytosis, severe congenital neutropenia, severe infantile genetic neutropenia, infantile genetic agranulocytosis or Kostmann disease.

CTLA4 deficiency impairs normal regulation of the immune system, resulting in excessive numbers of immune cells called lymphocytes, autoimmunity, low levels of antibodies, and recurrent infections.

Dengue fever is an infectious disease carried by mosquitoes and caused by any of four related dengue viruses. This disease used to be called "break-bone" fever because it sometimes causes severe joint and muscle pain that feels like bones are breaking. Health experts have known about dengue fever for more than 200 years. 

DOCK8 deficiency is a rare immune disorder named after the mutated gene responsible for the disease. The disorder causes decreased numbers and dysfunction of immune cells, as well as poor ability of immune cells to move across dense tissues like the skin. The abnormalities resulting from DOCK8 defects lead to recurrent infections.

Escherichia coli (E. coli) bacteria live in the intestines of people and animals, and are key to a healthy intestinal tract. Most E. coli strains are harmless, but some can cause diarrhea through contact with contaminated food or water while other strains can cause urinary tract infections, respiratory illness and pneumonia.

Ebola and Marburg hemorrhagic fevers are acute viral diseases that often lead to severe illness and death in humans and other primates. The infections typically affect multiple organs in the body and are often accompanied by hemorrhage (bleeding). Once the virus has been transmitted from an animal host to a human, it can then spread through person-to-person contact.

Atopic dermatitis, also known as eczema, is a non-contagious inflammatory skin condition. It is a chronic disease characterized by dry, itchy skin that can weep clear fluid when scratched. People with eczema also may be particularly susceptible to bacterial, viral, and fungal skin infections.

NIAID is the lead Institute at the National Institutes of Health conducting research on food allergy, a condition that affects approximately 5 percent of children and 4 percent of adults in the United States. In a person with food allergy, the immune system reacts abnormally to a component of a food—sometimes producing a life-threatening response.

GATA2 deficiency is a genetic disease that can manifest as five distinct syndromes: monocytopenia and mycobacterial infection syndrome; dendritic cell, monocyte, B, and natural killer lymphoid deficiency; familial myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML); Emberger syndrome; or natural killer (NK) cell deficiency.

Glycosylation refers to the attachment of sugars to proteins, a normal process required for the healthy function of cells. Defects in glycosylation can impair the growth or function of cells and tissues in the body, and in some cases, the immune system is disrupted, resulting in immunodeficiency.

Gonorrhea is a sexually transmitted disease that can infect both men and women. Caused by the Neisseria gonorrhoeae bacterium, gonorrhea can cause infections in the genitals, rectum and throat. Although treatable, drug-resistant forms of gonorrhea are increasing.

Group A streptococcal (GAS) infections can range from a mild skin infection or a sore throat to severe, life-threatening conditions. Most people are familiar with strep throat, which along with minor skin infections, is the most common form of the disease.

Hepatitis is an inflammation of the liver. Viruses are the most common cause of hepatitis, but the condition can also be caused by other infections, heavy alcohol use, toxins, certain medications, and autoimmune disease. There are five main virus types that cause hepatitis---type A, B, C, D and E. Hepatitis A and E are typically caused by ingesting contaminated food or water. Type B commonly occurs through contact with infected blood, semen or other bodily fluid through sex, sharing needles or other drug-injection equipment or from mother to baby at birth.

HIV, or human immunodeficiency virus, is the virus that causes AIDS (Acquired Immunodeficiency Syndrome). HIV attacks the immune system by destroying CD4 positive (CD4+) T cells, a type of white blood cell that is vital to fighting off infection. The destruction of these cells leaves people living with HIV vulnerable to other infections, diseases and other complications. As the leading U.S. government institute for HIV/AIDS research, NIAID is committed to conducting the research necessary to successfully end the fight against HIV/AIDS. 

People with hyper-immunoglobulin E syndrome, or HIES, have recurrent infections of the skin and lungs caused by bacteria. Patients with HIES typically also have eczema, very high levels of a type of antibody called immunoglobulin E (IgE), distinct facial features, and a tendency to experience bone fractures. HIES is also called Job’s Syndrome.

Hyper-IgM syndromes are conditions in which the immune system fails to produce normal levels of immunoglobulin A (IgA), IgG, and IgE antibodies but can produce normal or elevated levels of IgM. Various gene defects can cause hyper-IgM syndromes.

Influenza, or flu, is a contagious respiratory infection caused by several flu viruses that infect the nose, throat and lungs. People infected with the seasonal flu virus feel miserable with fever, chills, muscle aches, coughing, congestion, headache and fatigue for a week or so. Most people who get the flu get better within two weeks, but some people may develop serious complications, such as pneumonia. Pandemic influenza is when a new flu virus strain occurs that can spread easily from person-to-person and the virus is one for which most people have no immunity.

The immune system is a network of cells, tissues, and organs that work together to protect the body from infection. Immune cells communicate using a series of signals that can be secreted into the cell’s environment or expressed on the surface of the cell. Interferon gamma (IFN-γ), interleukin 12 (IL-12), and interleukin 23 (IL-23) are key signal molecules that raise an alert against bacteria and other infectious microbes.

Leishmaniasis is a parasitic disease transmitted by the bites of infected sand flies. It is found in nearly 88 countries, from rain forests in Central and South America to deserts in the Middle East and west Asia. Some cases of the disease have also appeared in Mexico and Texas. The disease takes several different forms, including the most common cutaneous leishmaniasis, which causes skin sores, and the more severe visceral leishmaniasis (also known as kala azar), which affects internal organs such as the spleen, liver, and bone marrow. 

Leprosy (Hansen's Disease) is a chronic infectious disease that primarily affects the peripheral nerves, skin, upper respiratory tract, eyes, and nasal mucosa (lining of the nose). The disease is caused by a bacillus (rod-shaped) bacterium known as Mycobacterium leprae.

Leukocyte adhesion deficiency (LAD) is an immune deficiency in which immune cells called phagocytes are unable to move to the site of an infection to fight off invading germs. This inability to fight germs results in recurrent, life-threatening infections and poor wound healing.

Lyme disease, or borreliosis, is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of an infected blacklegged deer tick. It is the most common tickborne infectious disease in the United States.  

Malaria is a mosquito-borne disease that can cause infected people to become very sick with high fever, chills, and flu-like illness. It can also cause death. Substantial progress has been made globally to control and eliminate malaria, but it continues to be a significant public health problem with roughly 3.2 billion people worldwide at risk for the disease.

Middle East Respiratory Syndrome (MERS-CoV) is a viral respiratory illness that was first reported in Saudi Arabia in 2012 and has since spread to several other countries. Most people infected with MERS-CoV developed severe acute respiratory illness, including fever, cough, and shortness of breath; many of them died. Severe acute respiratory syndrome (SARS-CoV), also a severe viral respiratory illness, was first reported in Asia in February 2003 and spread to dozens of countries before being contained. Since 2004, there have been no known SARS cases.

Pertussis, also known as whooping cough, is a highly contagious respiratory disease. It is caused by the bacterium Bordetella pertussis. Pertussis is known for uncontrollable, violent coughing that often makes it hard to breathe. After fits of many coughs, someone with pertussis often needs to take deep breaths, which result in a “whooping” sound.

Discovered by NIH scientists in 2013, PI3 kinase (PI3K) disease is named after the genetic mutations that cause the disorder and its symptoms. People with PI3K disease have a weakened immune system and experience frequent bacterial and viral infections. PI3K disease also increases a person’s risk of lymphoma, a type of immune cell cancer.

The disease also is called PI3K-p110δ activating mutation causing senescent T cells, lymphadenopathy, and immunodeficiency (PASLI) or activating PI3K delta syndrome (APDS).

Plague, caused by the bacterium Yersinia pestis, is a disease that affects humans and other mammals. People typically get infected after being bitten by a rodent flea that is carrying the bacterium or by handling a plague-infected animal. Although the disease killed millions in Europe during the Middle Ages, antibiotics effectively treat plague today. Without prompt treatment, plague can cause serious illness or death. Human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia.

PLAID and PLAID-like diseases are rare immune disorders with overlapping features, and an allergic response to cold, called cold urticaria, is the most distinct symptom.

Primary immune deficiency diseases (PIDDs) are rare, genetic disorders that impair the immune system. Without a functional immune response, people with PIDDs may be subject to chronic, debilitating infections, such as Epstein-Barr virus (EBV), which can increase the risk of developing cancer. Some PIDDs can be fatal. PIDDs may be diagnosed in infancy, childhood, or adulthood, depending on disease severity.

Prion diseases are a related group of rare, fatal brain diseases that affect animals and humans. Also known as transmissible spongiform encephalopathies (TSE), they include bovine spongiform encephalopathy ("mad cow" disease) in cattle; Creutzfeldt-Jakob disease in humans; scrapie in sheep; and chronic wasting disease in deer and elk.

Respiratory syncytial virus, or RSV, is a respiratory virus that infects the lungs and breathing passages. Healthy people typically experience mild, cold-like symptoms and recover in a week or two. However, RSV can be serious, particularly for infants and the elderly. RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia in children younger than 1 year of age in the United States.

Rocky Mountain spotted fever is a tickborne disease first recognized in 1896 in the Snake River Valley of Idaho. It was originally called “black measles” because of the look of its rash in the late stages of the illness, when the skin turns black. It was a dreaded, often fatal disease, affecting hundreds of people in Idaho. By the early 1900s, the disease could be found in Washington, Montana, California, Arizona, and New Mexico.

Schistosomiasis, also known as bilharzia, is a neglected tropical disease caused by parasitic worms. It is second only to malaria as the most devastating parasitic disease. The parasites that cause schistosomiasis live in certain types of freshwater snails. The infectious form of the parasite emerge from the snail and then contaminate the water. People become infected when their skin comes into contact with the contaminated freshwater. Most human infections are caused by Schistosoma mansoni, S. haematobium, or S. japonicum.

SCID is a group of rare disorders caused by mutations in different genes involved in the development and function of infection-fighting T, B, and natural killer cells. Infants with SCID appear healthy at birth but are highly susceptible to severe infections. The condition is fatal, usually within the first year or two of life, unless infants receive immune-restoring treatments, such as transplants of blood-forming stem cells, gene therapy, or enzyme therapy. More than 80 percent of SCID infants do not have a family history of the condition.

Sexually transmitted diseases (STDs) are infections transmitted from an infected person to an uninfected person through sexual contact. STDs can be caused by bacteria, viruses, or parasites. Examples include gonorrhea, genital herpes, human papillomavirus infection, HIV/AIDS, chlamydia, and syphilis.

Shigellosis is an infectious, diarrheal disease caused by a group of bacteria called Shigella. It is transmitted via contact with contaminated food, water, surfaces or an infected person. The disease typically resolves in 5 to 7 days. Shigella causes roughly 500,000 cases of diarrhea in the United States each year.

Smallpox, caused by the variola virus, was a highly contagious infectious disease that caused infected individuals to develop a fever and a progressive, disfiguring skin rash. Three of out 10 individuals infected with smallpox died. Many survivors have permanent scars, often on their faces, or were left blind. Through vaccination, the disease was eradicated in 1980.  However, research for effective vaccines, drugs and diagnostics for smallpox continues in the event it is used as a bioterror weapon.

Syphilis is a sexually transmitted disease caused by the bacterium Treponema pallidum. It is transmitted from person to person via direct contact with a syphilitic sore, known as a chancre. These sores can be found on the genitals, vagina, anus, rectum, lips and mouth. Pregnant women can transmit the disease to their unborn child.  Syphilis can cause long-term health complications if left untreated.

Tickborne diseases are becoming a serious problem in the United States as people increasingly build homes in formerly uninhabited wilderness areas where ticks and their animal hosts live. Tickborne diseases can be caused by viruses, bacteria, or parasites. Most people become infected through tick bites during the spring and summer months.

Tuberculosis (TB) is a contagious and often severe airborne disease caused by infection with Mycobacterium tuberculosis (Mtb) bacteria. TB typically affects the lungs, but it also can affect any other organ of the body. It is usually treated with a regimen of drugs taken for six months to two years depending on whether the infecting organisms are drug resistant.

WHIM syndrome is a rare immune disorder named after its symptoms: warts, hypogammaglobulinemia (low antibody levels), infections, and myelokathexis (inability of white blood cells to move from the bone marrow into the bloodstream). People with WHIM syndrome have low levels of infection-fighting white blood cells, especially neutrophils, in their bloodstream. This deficiency predisposes them to frequent infections and persistent warts.

West Nile virus (WNV), a mosquito-borne illness, first emerged in the Western Hemisphere in 1999 in the New York City area and has since spread across the United States. Most people infected with WNV will have no symptoms. About 1 in 5 people infected will develop a fever with other symptoms. Less than 1 percent of those infected will develop a serious, sometimes fatal, neurologic illness.

People with WAS have problems with their B cells, T cells, and platelets (blood components that aid in clotting). This can result in prolonged episodes of bleeding, recurrent bacterial and fungal infections, and increased risk of cancers and autoimmune diseases.

LA is an inherited immune disorder caused by an inability to produce B cells or the immunoglobulins (antibodies) that the B cells make. The mutated gene responsible for XLA (Bruton tyrosine kinase or BTK) is located on the X chromosome. XLA is also called Bruton type agammaglobulinemia, X-linked infantile agammaglobulinemia, and congenital agammaglobulinemia.

XLP primarily affects boys and is characterized by a life-long vulnerability to Epstein-Barr virus (EBV), a common type of herpesvirus that usually does not cause symptoms other than a brief infection or mononucleosis. Boys with XLP, however, can have severe reactions to EBV infections.

Discovered in the Zika forest, Uganda, in 1947, Zika virus is a member of the flavivirus family. Other flaviviruses include those that cause dengue, yellow fever, and West Nile fever. Like its relatives, Zika virus is primarily transmitted to humans through the bite of infected Aedes aegypti mosquitoes. Zika virus can be transmitted from an infected pregnant woman to her baby during pregnancy and can result in serious birth defects, including microcephaly. Less commonly, the virus can be spread through intercourse or blood transfusion.