A blood disorder characterized by low levels of white blood cells (granular leukocytes) in the circulating blood. The condition is usually caused by certain drugs especially chemotherapy drugs....

The appendix is a small, worm-like appendage attached to the colon. Appendicitis occurs when bacteria invade and infect the wall of the appendix. The most common complications of appendicitis are rupture, abscess, and peritonitis....

Chikungunya is a rare viral infection transmitted by the bite of an infected mosquito. It is characterized by a rash, fever, and severe joint pain (arthralgias) that usually lasts for three to seven days. Because of its effect on the joints, Chiku...

Polymyalgia rheumatica is a rare inflammatory disease characterized by muscle pain (myalgia), stiffness, and additional generalized systemic symptoms such as fatigue, low-grade fever, and/or a general feeling of ill health (malaise). Polymyalgia r...

Like many people with chronic ailments, sufferers of chronic arthritis are potentially vulnerable to proponents of heavily marketed "cure-all" treatments. These "quick fix" treatments are promoted as having great benefits, but in reality have no r...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Bile duct cancer, also called cholangiocarcinoma, is when unusual cells grow out of control inside your bile ducts. Those are thin tubes about 4 to 5 inches long that move a fluid called bile from your liver to your gallbladder and small intestine...

Bile duct cancer, also called cholangiocarcinoma, is when unusual cells grow out of control inside your bile ducts. Those are thin tubes about 4 to 5 inches long that move a fluid called bile from your liver to your gallbladder and small intestine...

Kernicterus is a rare neurological disorder characterized by excessive levels of bilirubin in the blood (hyperbilirubinemia) during infancy. Bilirubin is an orange-yellow bile pigment that is a byproduct of the natural breakdown of hemoglobin in r...

Blue diaper syndrome is a rare, genetic metabolic disorder characterized by the incomplete intestinal breakdown of tryptophan, a dietary nutrient. Symptoms typically include digestive disturbances, fever, irritability and visual difficulties. Some...

Bocavirus is a virus that causes the common cold and other respiratory infections. Cold, fever, runny nose, and cough are the most common symptoms. It can also cause gastroenteritis, or stomach flu, which can cause severe stomach and intestine irr...

General DiscussionChagas Disease is a tropical infectious disease caused by the parasite Trypanosoma cruzi. It is transmitted by the bite of one of several species of blood-sucking insects or by blood transfusion. Acute Chagas Disease usu...

Dengue Fever is an acute viral infection characterized by fever. It is caused by a bite from mosquitoes carrying dengue virus. The primary form of Dengue Fever is characterized by a skin rash and a high fever with severe pain in the head and muscl...

Bronchitis is an infection that causes irritation and inflammation in the lungs' major airways (bronchi). Bronchitis is divided into two types: acute and chronic. Chronic bronchitis is a long-term condition that can reoccur. Long-term stress, such...

Bronchitis is an infection that affects the lungs' major airways (bronchi), causing irritation and inflammation. Bronchitis can be classified into two types: acute and long-term. Chronic bronchitis is a long-term problem that can come back. It is usu...

Campylobacteriosis is a bacterial infection caused by Campylobacter bacteria. It is one of the most common causes of foodborne illness in the world, typically contracted through the consumption of contaminated food or water. Symptoms of campylobac...

  Cellulitis is a spreading bacterial infection of the skin and tissues beneath the skin. Staphylococcus and Streptococcus are the types of bacteria that are usually responsible for cellulitis, although many types of ...

Chickenpox (varicella) is a viral infection that causes an itchy rash with small, fluid-filled blisters. Chickenpox is highly contagious to people who haven't had the disease or been vaccinated against it. Before routine chickenpox vaccination, vi...

Chickenpox, also known as varicella, is a highly contagious viral infection caused by the varicella-zoster virus. It is characterized by a red, itchy rash that usually starts on the face, chest, and back and then spreads to the rest of the body. O...

Chikungunya is a viral disease transmitted to humans by infected mosquitoes, specifically the Aedes aegypti and Aedes albopictus species. The most common symptoms of Chikungunya include fever, joint pain, headache, muscle pain, rash, and joint swe...

Childhood acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many immature lymphocytes (a type of white blood cell). Childhood acute lymphoblastic leukemia (also called acute lymphocytic leukemia or A...

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease ...

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. ...

Mixed connective tissue disease facts Connective tissues are the framework of the cells of the body. Mixed connective tissue disease is an "overlap" combination of connective tissue diseases. Diagnosis of mixed c...

COVID-19 is a highly contagious respiratory illness caused by the novel coronavirus SARS-CoV-2. It was first identified in Wuhan, China in late 2019 and has since spread globally, leading to a pandemic. Symptoms of COVID-19 can range from mild to ...

Croup is a common childhood illness that causes swelling of the upper respiratory tract. This can be recognised by a change in tone of voice and a distinctive "croupy" cough that sounds like a seal or barking. Croup is caused by a variety of virus...

Mixed cryoglobulinemia is a rare disorder characterized by the presence of cryoglobulins in the blood. Cryoglobulins are abnormal proteins that thicken and clump together at cold temperatures, usually below 98.6 degrees Fahrenheit (the average hum...

Cryptococcus is a fungus that is found in soil all over the world, usually in association with bird droppings. Cryptococcus neoformans is the most common Cryptococcus species that causes illness in humans. Cryptococcus gattii, a less common specie...

Cryptosporidiosis is a diarrheal disease caused by microscopic parasites, Cryptosporidium, that can live in the intestine of humans and animals and is passed in the stool of an infected person or animal. Both the disease and the parasite are commo...

Cryptosporidiosis is a parasitic infection caused by the Cryptosporidium parasite. It is typically transmitted through contaminated water or food, or through contact with infected animals or people. Symptoms of cryptosporidiosis include diarrhea, ...

Cyclic neutropenia is a rare blood disorder characterized by recurrent episodes of abnormally low levels of certain white blood cells (neutrophils) in the body. Neutrophils are instrumental in fighting off infection by surrounding and destroying b...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Autosomal dominant interstitial kidney disease describes a group of diseases affecting solely the proper function of the kidney and having the following characteristics: They are inherited in an autosomal dominant manner; kidney disease develops, ...

Cytomegalovirus infection (CMV) is a viral infection that rarely causes obvious illness. The virus that causes CMV is part of the herpes virus family and, like other herpes viruses, may become dormant for a period of time and then be reactivated. ...

Cytomegalovirus (CMV) is a common virus that belongs to the herpesvirus family. It can infect people of all ages and is usually harmless to those with a healthy immune system. However, it can cause serious complications in individuals with weakene...

What is the difference between diabetes insipidus and diabetes mellitus Diabetes insipidus should not be confused with diabetes mellitus (DM), which results from insulin deficiency or resistance leading to high blood glucose, also called b...

What is the difference between diabetes insipidus and diabetes mellitus Diabetes insipidus should not be confused with diabetes mellitus (DM), which results from insulin deficiency or resistance leading to high blood glucose, also called b...

Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distin...

Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distin...

Diphtheria is a serious bacterial infection that usually affects the mucous membranes of the throat and nose. It is caused by the bacterium Corynebacterium diphtheriae and is spread through respiratory droplets or direct contact with an infected p...

Blue diaper syndrome is a rare, genetic metabolic disorder characterized by the incomplete intestinal breakdown of tryptophan, a dietary nutrient. Symptoms typically include digestive disturbances, fever, irritability and visual difficulties. Some...

E. coli infection is a type of bacterial infection caused by the bacterium Escherichia coli. E. coli bacteria are commonly found in the intestines of humans and animals, and most strains are harmless. However, some strains of E. coli can cause ill...

Encephalitis is an inflammation of the brain. Meningitis is an inflammation of the membranes (called meninges) that surround the brain and spinal cord. Both infections can be caused by bacteria or viruses and rarely a fungus. ...

Herpes simplex encephalitis (HSE) is a rare neurological disorder characterized by inflammation of the brain (encephalitis). Common symptoms include headaches, fevers, drowsiness, hyperactivity, and/or general weakness. The disorder may have some ...

Japanese Encephalitis is a severe inflammation of the brain caused by the Japanese B Encephalitis Virus that is transmitted by the bite of infected mosquitoes in certain areas of the world, particularly Asia. This disorder most commonly affects ch...

Endocarditis is a serious inflammation of one of the four heart valves....

Endocarditis is a serious inflammation of one of the four heart valves....

Epilepsy is a central nervous system (neurological) disorder in which brain activity becomes abnormal, causing seizures or periods of unusual behavior, sensations and sometimes loss of awareness. Anyone can develop epilepsy. Epilepsy affec...

Erythema multiforme (EM) is the name applied to a group of hypersensitivity disorders, affecting mostly children and young adults, and characterized by symmetric red, patchy lesions, primarily on the arms and legs. The cause is unknown, but EM fre...

Until recently the relationship of Stevens-Johnson syndrome to other severe blistering disorders was a matter of some debate. Now a consensus seems to be evolving that describes SJS as a rare disorder involving lesions of the mucous membranes alon...

Erythema nodosum is a type of skin inflammation that is located in a certain portion of the fatty layer of skin. Erythema nodosum (also called EN) results in reddish, painful, tender lumps most commonly located in the front of the legs below the k...

Cryptococcosis is caused by a fungus known as Cryptococcosis neoformans. The infection may be spread to humans through contact with pigeon droppings or unwashed raw fruit. Contact with an infected individual may also spread the infection. Individu...

Extrinsic Allergic Pneumonia, also known as Allergic Interstitial Pneumonitis and Hypersensitivity Pneumonitis, is an inflammatory syndrome that affects the lungs. Extrinsic: the origin is an external matter - an antigen. Allergic: The cau...

Fabry disease is caused by the lack of or faulty enzyme needed to metabolize lipids, fat-like substances that include oils, waxes, and fatty acids. The enzyme is known as ceramide trihexosidase, also called alpha-galactosidase-A. A mutation in the...

General DiscussionWeil syndrome, a rare infectious disorder, is a severe form of the bacterial infection caused by Leptospira bacteria known as leptospirosis. Weil syndrome is characterized by dysfunction of the kidneys and liver, abnorma...

Fitz-Hugh-Curtis syndrome is a rare disorder that occurs almost exclusively in women. It is characterized by inflammation of the membrane lining the stomach (peritoneum) and the tissues surrounding the liver (perihepatitis). The muscle that separa...

Influenza, a viral infection, causes an illness that can range from mild to life-threatening. Influenza, more commonly known as the flu, is a viral infection of the respiratory tract that affects the nose, throat, and sometimes lungs. ...

Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency (G6PDD) is an inherited, sex-linked, metabolic disorder characterized by an enzyme defect that leads to the breakdown of red blood cells (hemolysis) upon exposure to stresses associated with some...

Krabbe's Leukodystrophy is a rare inherited lipid storage disorder caused by a deficiency of the enzyme galactocerebrosidase (GALC), which is necessary for the breakdown (metabolism) of the sphingolipids galactosylceremide and psychosine. Failure ...

Krabbe's Leukodystrophy is a rare inherited lipid storage disorder caused by a deficiency of the enzyme galactocerebrosidase (GALC), which is necessary for the breakdown (metabolism) of the sphingolipids galactosylceremide and psychosine. Failure ...

Krabbe's Leukodystrophy is a rare inherited lipid storage disorder caused by a deficiency of the enzyme galactocerebrosidase (GALC), which is necessary for the breakdown (metabolism) of the sphingolipids galactosylceremide and psychosine. Failure ...

Schindler disease is a rare inherited metabolic disorder characterized by the deficient activity of the lysosomal enzyme alpha-N-acetylgalactosaminidase (alpha-NAGA or alpha-galactosidase B). The enzyme defect leads to the abnormal accumulation of...

Definition of gastroenteritis Gastroenteritis (often referred to as the "stomach flu," however, it is not related to the influenza virus. Gastroenteritis is a nonspecific term for various inflammatory problems in the gastrointestinal tract...

Genital herpes is a sexually transmitted disease caused by herpes simplex virus (HSV). HSV causes genital herpes by entering the skin or mucous membranes through microscopic breaks in the skin and mucous membranes. Genital...

Krabbe's Leukodystrophy is a rare inherited lipid storage disorder caused by a deficiency of the enzyme galactocerebrosidase (GALC), which is necessary for the breakdown (metabolism) of the sphingolipids galactosylceremide and psychosine. Failure ...

Fabry disease is a rare genetic disorder of fat (lipid) metabolism characterized by a deficiency of the enzyme alpha-galactosidase A (previously known as ceramide trihexosidase). The disorder belongs to a group of diseases known as lysosomal stora...

Acquired agranulocytosis is a rare, drug-induced blood disorder that is characterized by a severe reduction in the number of white blood cells (granulocytes) in the circulating blood. The name granulocyte refers to grain-like bodies within the cel...

Group B strep facts Group B strep are bacteria found normally in the intestine, vagina, and rectal area in about 25% of all healthy women. Group B strep infections can affect neonates and adults. Most pregnant wo...

Group B Strejsonococcus (GBS) is a type of bacteria that is commonly found in the gastrointestinal tract, vagina, and rectum of healthy individuals. While GBS is usually harmless in healthy adults, it can cause serious infections in newborn babies...

Haemophilus influenzae type b (Hib) is a type of bacteria that can cause serious infections, particularly in young children. It can lead to illnesses such as meningitis, pneumonia, and epiglottitis. The Hib vaccine is highly effective in preventin...

Hand, Foot, and Mouth Disease (HFMD) is a common viral illness that usually affects infants and children under the age of 5, although it can also occur in older children and adults. It is caused by several different viruses, most commonly the coxs...

Hemolytic uremic syndrome (HUS) is a condition caused by the abnormal destruction of red blood cells. The damaged red blood cells clog the filtering system in the kidneys, which can lead to life-threatening kidney failure. HUS usually deve...

Hereditary spherocytic hemolytic anemia is a rare blood disorder characterized by defects within red blood cells (intracorpuscular) that result in a shortened survival time for these cells. Red blood cells (erythrocytes) normally circulate for a f...

Herpangina facts Herpangina is a self-limited infection primarily caused by coxsackieviruses. Herpangina most often affects young children. Herpangina is associated with fever, sore throat, and blisters in the ba...

Herpes Simplex Virus (HSV) is a common viral infection that causes sores or blisters on the skin or mucous membranes. There are two types of HSV: HSV-1, which typically causes cold sores or fever blisters around the mouth, and HSV-2, which typical...

Kikuchi's disease, also known as histiocytic necrotizing lymphadenopathy, is a rare, benign, (noncancerous, nonmalignant) disorder of the lymph nodes of young adults, predominantly in young women. This disorder is often mistaken for malignant lymp...

Histoplasmosis is an infection caused by the fungus Histoplasma. The fungus can be found in the environment, particularly in soil with a high concentration of bird or bat droppings. Histoplasma is mostly found in the central and eastern United Sta...

Cowpox is a viral disease that normally affects the udders and teats of cows. On rare occasions, it may be transmitted to humans and produce a characteristic red skin rash and abnormally enlarged lymph nodes (lymphadenopathy). Cowpox is caused by ...

Human Immunodeficiency Virus (HIV) is a virus that attacks the immune system, specifically targeting CD4 cells (T cells), which help the body fight off infections. If left untreated, HIV can lead to the disease known as Acquired Immunodeficiency S...

Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder characterized by growth delays before and after birth (prenatal and postnatal growth retardation), short stature, a varying degree of mental deficiency, and dist...

If you’ve got a nagging pain on the outer part of your knee, especially if you’re a runner, it could be a symptom of iliotibial band (IT band) syndrome. It’s an injury often caused by activities where you bend your knee repeatedl...

Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness and can sometimes lead to hospitalization or even death. Symptoms of the flu include fever, cough, sore thro...

Japanese enenchephalitis is a viral infection that is transmitted through the bite of infected mosquitoes. It is a type of encephalitis, which is inflammation of the brain. Symptoms of Japanese encephalitis can include fever, headache, vomiting, c...

Until recently the relationship of Stevens-Johnson syndrome to other severe blistering disorders was a matter of some debate. Now a consensus seems to be evolving that describes SJS as a rare disorder involving lesions of the mucous membranes alon...

Kawasaki's disease facts Kawasaki's disease is a syndrome of unknown cause that mainly strikes young children. Signs of the disease include fever and redness of the eyes, hands, feet, mouth, and tongue. The disea...

Kikuchi's disease, also known as histiocytic necrotizing lymphadenopathy, is a rare, benign, (noncancerous, nonmalignant) disorder of the lymph nodes of young adults, predominantly in young women. This disorder is often mistaken for malignant lymp...

Madelung's disease is a disorder of fat metabolism (lipid storage) that results in an unusual accumulation of fat deposits around the neck and shoulder areas. Adult alcoholic males are most often affected, although women and those who do not drink...

Childhood acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many immature lymphocytes (a type of white blood cell). Childhood acute lymphoblastic leukemia (also called acute lymphocytic leukemia or A...

Papular urticaria, usually called hives, is characterized by large numbers of very itchy red bumps (papules) that come and go every few days over a period of a month or so. The bumps are usually between 0.2 and 2 cm. in size and some may develop i...

Von Hippel-Lindau syndrome (VHL) is an autosomal dominant genetic disorder characterized by the abnormal growth of blood vessels in certain parts of the body (angiomatosis). Very small blood vessels (capillaries) "knot" together to form benign gro...

Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes. It primarily affects pregnant women, newborns, the elderly, and individuals with weakened immune systems. Symptoms may include...

Listeriosis is an infection caused by a gram-positive motile bacterium named Listeria monocytogenes. The infection produces fever, muscle aches, and, in many people, diarrhea. Severe infections can cause headaches, meningitis, convulsions, and dea...

Drug-induced liver diseases are diseases of the liver that are caused by physician-prescribed medications, over-the-counter medications, vitamins, hormones, herbs, illicit ("recreational") drugs, and environmental toxins. What is the liver...

Loeffler's disease is a transient respiratory illness associated with the higher production of a type of disease-fighting white blood cell usually called eosinophils in the lungs.  Loeffler's disease or syndrome is also re...

Congenital syphilis is a chronic infectious disease caused by a spirochete (treponema pallidum) acquired by the fetus in the uterus before birth. Symptoms of this disease may not become apparent until several weeks or months after birth and, in so...

Systemic lupus erythematosus (SLE) is an autoimmune disease. SLE is characterized by the production of unusual antibodies in the blood. SLE is eight times more common in women than men. The cause(s) of SLE is (ar...

Measles is a highly contagious viral infection that primarily affects children. It is characterized by a red, blotchy rash that typically starts on the face and spreads to the rest of the body. Other symptoms of measles include fever, cough, runny...

Encephalitis is an inflammation of the brain. Meningitis is an inflammation of the membranes (called meninges) that surround the brain and spinal cord. Both infections can be caused by bacteria or viruses and rarely a fung...

Meningococcal disease is a serious bacterial infection caused by the bacterium Neisseria meningitidis. It can lead to meningitis (inflammation of the membranes surrounding the brain and spinal cord) and septicemia (blood poisoning). Meningococcal ...

Megalocornea-mental retardation (MMR) syndrome, otherwise known as Neuhauser syndrome, is an extremely rare genetic disorder characterized by distinctive abnormalities of the eye, several degrees of cognitive impairment, and a wide variety of addi...

Mononucleosis, commonly known as mono, is a viral infection caused by the Epstein-Barr virus (EBV). It is most commonly seen in teenagers and young adults, but can affect people of any age. Mono is typically spread through saliva, which is why it ...

Colorado Tick Fever is a rare viral disease transmitted by ticks that commonly inhabit the western United States. Major symptoms may include fever, headaches, muscle aches, and/or generalized discomfort (myalgia). The symptoms usually last for abo...

Mucha-Habermann disease, also known as pityriasis lichenoides et varioliformis acuta or PLEVA, is a rare skin disorder. The lesions most often appear on the trunk and the arms and legs. Lesions tend to develop in small groups. Mucha-Habermann dise...

Mumps is a contagious viral infection that primarily affects the salivary glands, causing swelling and pain in the cheeks and jaw. It is spread through respiratory droplets, such as coughing or sneezing, and can also be transmitted through close p...

Flesh-eating bacteria (necrotizing fasciitis) is a rare infection of the skin and tissues below it. It can be deadly if not treated quickly. Necrotizing fasciitis spreads quickly and aggressively in an infected person. It causes tissue dea...

Necrotizing Sarcoid Granulomatosis (NSG) is a rare granulomatous illness that primarily affects the lungs and manifests as nodular masses of confluent sarcoid-like granulomas with severe necrosis and vasculitis. It was first described in 1973, as ...

Listeriosis is a rare but serious infectious disease caused by the bacterium Listeria monocytogenes, which is predominantly transmitted to humans through the consumption of contaminated food. Clinical syndromes associated with listeriosis include ...

General DiscussionNeonatal lupus is a rare autoimmune disorder that is present at birth (congenital). Affected infants often develop a characteristic red rash or skin eruption. In addition, infants with neonatal lupus may develop liver di...

Renal cell carcinoma is a form of kidney cancer. Some patients with renal cell carcinoma do not have symptoms (asymptomatic). When symptoms are present, they may include blood in the urine; urine that is brown or rusty-colored; abdominal pain; wei...

Henoch-Schonlein purpura is a rare inflammatory disease of the small blood vessels (capillaries) and is usually a self-limited disease. It is the most common form of childhood vascular inflammation (vasculitis) and results in inflammatory changes ...

Norovirus is a highly contagious virus that causes gastroenteritis, which is inflammation of the stomach and intestines. It is commonly referred to as the "stomach flu" or "winter vomiting bug" because it often causes symptoms such as vomiting, di...

Osgood-Schlatter disease facts Osgood-Schlatter disease is a painful inflammation in the front of the bony leg below the knee. Osgood-Schlatter disease can cause local pain, inflammation, swelling, and calcification. ...

Hyperoxaluria occurs when you have too much oxalate in your urine. Oxalate is a natural chemical in your body, and it's also found in certain types of food. But too much oxalate in your urine can cause serious problems. Hyperoxaluria can b...

Idiopathic nodular panniculitis is a rare spectrum of skin disorders characterized by single or multiple, tender or painful bumps below the surface of the skin (subcutaneous nodules) that usually lead to inflammation of the subcutaneous layer of f...

Idiopathic nodular panniculitis is a rare spectrum of skin disorders characterized by single or multiple, tender or painful bumps below the surface of the skin (subcutaneous nodules) that usually lead to inflammation of the subcutaneous layer of f...

Pelvic Inflammatory Disease (PID) is an infection of the female reproductive organs, including the uterus, fallopian tubes, and ovaries. It is usually caused by sexually transmitted infections such as chlamydia and gonorrhea, but can also be cause...

What is pericarditis? The heart muscle has a tight covering that surrounds it, a lining sac called the pericardium (peri=around +cardium=heart). This sac actually has two layers. The visceral pericardium is only one cell layer thick and fi...

Pertussis, also known as whooping cough, is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis. It is characterized by severe coughing fits that can be followed by a "whooping" sound when the person tries to tak...

Phlebitis refers to inflammation of a vein and it can be caused by any insult to the blood vessel wall, impaired venous flow, or coagulation abnormality. Pain, swelling, redness, and tenderness are some common symptoms of phlebitis....

Phlebitis refers to inflammation of a vein and it can be caused by any insult to the blood vessel wall, impaired venous flow, or coagulation abnormality. Pain, swelling, redness, and tenderness are some common symptoms of phlebitis....

Pleurisy (pleuritis) is a health condition that occurs when the pleura, the thin layer of tissue that covers the lungs, becomes inflamed. Pleurisy (pleuritis) can be caused by a variety of things, including viruses, bacteria, and even lung cancer....

Pneumonia is an inflammatory infection that develops in the lungs. This disease fills up air sacs with fluid or pus that leads to cough with phlegm, fever, and difficulty in breathing. We inhale air from the nose or mouth that reach...

Pneumonia is a lung infection that can be caused by bacteria, viruses, or fungi. It causes inflammation in the air sacs in the lungs, leading to symptoms such as cough, fever, difficulty breathing, and chest pain. Pneumonia can range from mild to ...

Polio, short for poliomyelitis, is a highly contagious viral infection that can lead to paralysis, muscle weakness, and in severe cases, death. It primarily affects children under the age of 5. The virus is spread through contaminated food and wat...

Polymyalgia rheumatica and giant cell arteritis facts Polymyalgia rheumatica causes pain and stiffness in muscles and joints. Polymyalgia rheumatica is diagnosed by characteristic symptoms associated with abnormal blood te...

Pulmonary alveolar proteinosis is a lung disorder characterized by a build-up of proteins, lipids, and other substances (together known as surfactants) in the lungs' air sacs, or alveoli. The alveoli are the air-holding cells in the lungs. The exc...

Pulmonary angiitis is a term used to describe a collection of disorders with both a vascular (angiitis) and granulomatous components. It means inflammation of blood vessels in the lungs.  There are five unique clinical syndromes that ...

Lymphomatoid granulomatosis is a rare disorder characterized by overproduction (proliferation) of white blood cells called lymphocytes (lymphoproliferative disorder). The abnormal cells infiltrate and accumulate (form lesions or nodules) within ti...

Thrombotic thrombocytopenia purpura (TTP) is a rare, serious blood disease. Major symptoms may include a severe decrease in the number of blood platelets (thrombocytopenia), abnormal destruction of red blood cells (hemolytic anemia), and disturban...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Infectious arthritis is an inflammation of one or more joints that occurs as a result of infection by bacteria, viruses or, less frequently, fungi or parasites. The symptoms of Infectious arthritis depend upon which agent has caused the infection ...

Rabies is a viral disease that affects the central nervous system of mammals, including humans. It is usually transmitted through the bite of an infected animal, such as a dog, bat, raccoon, or fox. Rabies is a serious and often fatal disease if n...

Radiation sickness describes the harmful effects--acute, delayed, or chronic--produced by exposure to ionizing radiation. An observable effect due to radiation exposure becomes quite certain after a single dose of several hundred rads. As a rule, ...

Radiation sickness describes the harmful effects--acute, delayed, or chronic--produced by exposure to ionizing radiation. An observable effect due to radiation exposure becomes quite certain after a single dose of several hundred rads. As a rule, ...

Radiation sickness is damage to your body caused by a large dose of radiation often received over a short period of time (acute). The amount of radiation absorbed by the body — the absorbed dose — determines how sick you'll be. ...

Radiation sickness describes the harmful effects--acute, delayed, or chronic--produced by exposure to ionizing radiation. An observable effect due to radiation exposure becomes quite certain after a single dose of several hundred rads. As a rule, ...

Respiratory Syncytial Virus (RSV) is a common respiratory virus that can cause mild, cold-like symptoms in adults and older children, but can be more serious in infants and young children. RSV is highly contagious and spreads through respiratory d...

Respiratory syncytial virus (RSV) infection is a common respiratory virus that causes cold-like symptoms. It commonly affects infants by the time they reach the age of two.  Respiratory syncytial virus (RSV) infection symptoms ...

Toxic epidermal necrolysis (TEN) is a rare, sometimes life-threatening unless properly treated, immunological disorder of the skin. It is characterized by blisters that meld into one another to cover a substantial portion of the body (30% and more...

Rosai-Dorfman disease is a rare disorder characterized by overproduction (proliferation) and accumulation of a specific type of white blood cell (histiocyte) in the lymph nodes of the body (lymphadenopathy), most often those of the neck (cervical ...

Roseola facts Roseola is a mild illness caused by a virus infection most commonly involving, young children. A sudden high fever that lasts for three to five days is an early feature of roseola. Mild nasal congestion and l...

Rotavirus is a highly contagious virus that causes inflammation of the stomach and intestines, leading to symptoms such as severe diarrhea, vomiting, fever, and abdominal pain. It is a common cause of gastroenteritis in infants and young children,...

Rubella, also known as German measles, is a contagious viral infection that causes a mild fever and a red rash on the skin. It is typically a mild illness, but can be more serious for pregnant women, as it can cause birth defects in the developing...

Japanese Encephalitis is a severe inflammation of the brain caused by the Japanese B Encephalitis Virus that is transmitted by the bite of infected mosquitoes in certain areas of the world, particularly Asia. This disorder most commonly affects ch...

Typhoid fever is a bacterial infection that is rare in the United States. However, it is not rare in many other countries. Major symptoms may include unusually high fever, headache, loss of appetite, fatigue, abdominal pain and diarrhea....

Salmonellosis is a type of food poisoning caused by the Salmonella bacteria. It is typically contracted by consuming contaminated food or water. Symptoms of salmonellosis include diarrhea, fever, abdominal cramps, and vomiting. In most cases, the ...

Toxic epidermal necrolysis (TEN) is a rare, sometimes life-threatening unless properly treated, immunological disorder of the skin. It is characterized by blisters that meld into one another to cover a substantial portion of the body (30% and more...

Shigellosis is an infectious disease caused by a group of bacteria called Shigella. It is typically spread through contaminated food or water, or through close contact with an infected person. Symptoms of shigellosis can include diarrhea, fever, s...

Mucopolysaccharidoses, which are also known as mucopolysaccharide storage (MPS) diseases, are a group of rare genetic disorders caused by the deficiency of one of ten specific lysosomal enzymes. The lysosomes are particles bound in membranes withi...

Smallpox facts Smallpox is a contagious disease caused by the variola virus. Smallpox was the first disease to be eliminated from the world through public-health efforts and vaccination. Smallpox still poses a th...

Felty syndrome is usually described as associated with or a complication of rheumatoid arthritis. This disorder is generally defined by the presence of three conditions: rheumatoid arthritis (RA), an enlarged spleen (spenomelgaly) and a low white ...

Sweet syndrome is a rare skin disorder characterized by fever, inflammation of the joints (arthritis), and the sudden onset of a rash. The rash consists of bluish-red, tender papules that usually occur on the arms, legs, face or neck, most often o...

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It can be transmitted through sexual contact, including vaginal, anal, and oral sex. Syphilis can also be passed from mother to baby during pregnancy or...

Congenital syphilis is a chronic infectious disease caused by a spirochete (treponema pallidum) acquired by the fetus in the uterus before birth. Symptoms of this disease may not become apparent until several weeks or months after birth and, in so...

Tetanus, also known as lockjaw, is a serious bacterial infection caused by the bacterium Clostridium tetani. The bacteria usually enter the body through a wound or cut, where they produce a toxin that affects the nervous system, leading to muscle ...

TORCH Syndrome refers to infection of a developing fetus or newborn by any of a group of infectious agents. "TORCH" is an acronym meaning (T)oxoplasmosis, (O)ther Agents, (R)ubella (also known as German Measles), (C)ytomegalovirus, and (H)erpes Si...

Cryptococcosis is caused by a fungus known as Cryptococcosis neoformans. The infection may be spread to humans through contact with pigeon droppings or unwashed raw fruit. Contact with an infected individual may also spread the infection. Individu...

Torulosis is an airborne disease. It is more famously referred to as cryptococcosis. When you inhale infected dust, torulosis slowly spreads throughout your lungs, presenting as pneumonia. It could potentially be fatal. Sometimes, i...

Toxoplasmosis is a disease caused by the Toxoplasma gondii parasite. It is commonly found in cat feces and can also be present in contaminated soil, water, and raw or undercooked meat. In healthy individuals, toxoplasmosis may cause mild flu-like ...

Travelers' diarrhea is defined by most experts as three or more unformed stools in a 24 hour time period, passed by a person who is traveling. Travelers' diarrhea is commonly accompanied by abdominal cramps, nausea, and bloating. Travelers' diarrh...

Tuberculosis (TB) is a contagious bacterial infection that primarily affects the lungs, but can also affect other parts of the body such as the kidneys, spine, and brain. It is caused by the bacterium Mycobacterium tuberculosis and is spread throu...

What is typhoid fever? What is the history of typhoid fever? Typhoid fever is an acute illness associated with fever that is most often caused by the Salmonella typhi bacteria. It can also be caused by Salmonella paratyphi, a related bacte...

Typhoid fever is a bacterial infection caused by Salmonella typhi bacteria. It is a serious illness that can be life-threatening if not treated promptly. Symptoms of typhoid fever include high fever, weakness, stomach pain, headache, and loss of a...

Tyrosinemia type I is a rare autosomal recessive genetic metabolic disorder characterized by lack of the enzyme fumarylacetoacetate hydrolase (FAH), which is needed for the final break down of the amino acid tyrosine. Failure to properly break dow...

Gilbert syndrome is a mild genetic liver disorder in which the body cannot properly process bilirubin, a yellowish waste product that is formed when old or worn out red blood cells are broken down (hemolysis). Individuals with Gilbert syndrome hav...

Reactive arthritis is a general term for a form of joint inflammation (arthritis) that develops as a "reaction" to an infection in another area of the body (i.e., outside of the joints). Joint inflammation is characterized by redness, swelling, pa...

Urinary tract infections are a fairly common problem in childhood and may have either a benign course responding to simple antibiotic therapy or be associated with significant disruption in either the anatomy or function of a child's urinary syste...

General DiscussionVACTERL association is a nonrandom association of birth defects that affects multiple median and para-median structures. The term VACTERL is an acronym with each letter representing the first letter of one of the more co...

General DiscussionVACTERL association is a nonrandom association of birth defects that affects multiple median and para-median structures. The term VACTERL is an acronym with each letter representing the first letter of one of the more co...

Varicella, commonly known as chickenpox, is a highly contagious viral infection caused by the varicella-zoster virus. It is characterized by an itchy rash with red spots and fluid-filled blisters that typically appear on the face, chest, back, and...

Cutaneous necrotizing vasculitis (CNV) is characterized by inflammation and tissue damage (necrosis) of blood vessel walls (lumen) and associated skin (cutaneous) lesions. CNV may be a primary disease process or occur as a result of, or in associa...

Nephrogenic diabetes insipidus (NDI) is a rare kidney disorder that may be inherited or acquired. NDI is not related to the more common diabetes mellitus (sugar diabetes), in which the body does not produce or properly use insulin. NDI is a distin...

Weber-Christian disease facts Weber-Christian disease is an uncommon inflammatory condition of the fatty tissues of the body. It's a disease of unknown cause. It most commonly affects the thighs and legs of women...

Weil syndrome, a rare infectious disorder, is a severe form of the bacterial infection caused by Leptospira bacteria known as leptospirosis. Weil syndrome is characterized by dysfunction of the kidneys and liver, abnormal enlargement of the liver ...

Familial eosinophilic cellulitis is a rare skin disorder. It is characterized by raised, red, swollen, and warm areas of skin, in a flame-shaped pattern with associated pain. The exact cause of the disease is unknown. However, bites of spiders, be...

Yellow fever is a viral infection that is transmitted through the bite of infected mosquitoes. The virus is primarily found in tropical and subtropical areas of Africa and South America. Symptoms of yellow fever can include fever, headache, muscle...

Takayasu arteritis is a rare disorder characterized by the progressive inflammation of one or more of the larger arteries leading from the heart. The main artery of the heart (aorta) and the pulmonary (lung) artery, among others, may be affected. ...

Zika virus is a mosquito-borne virus that is primarily transmitted to humans through the bite of an infected Aedes species mosquito. It can also be transmitted through sexual contact, blood transfusions, and from mother to fetus during pregnancy. ...