Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus. The virus is one of several types of hepatitis viruses that cause inflammation and affect your liver's ability to function. You're most likely to contract hepatitis A from contaminated food or water or from close contact with someone who's infected. Mild cases of hepatitis A don't require treatment, and most people who are infected recover completely with no permanent liver damage. Practicing good hygiene, including washing hands frequently, is one of the best ways to protect against hepatitis A. Vaccines are available for people most at risk.

An abscess is a collection of pus. Pus is a thick fluid that usually contains white blood cells, dead tissue and germs (bacteria). The usual cause of an abscess is an infection with bacteria. Certain bacteria are more likely to be 'pus-forming' as they make chemicals (toxins) that can damage the body's tissues.

The hepatitis E virus, responsible for major epidemics of viral hepatitis in subtropical and tropical countries, was cloned only 7 years ago.1 Hepatitis E was found to belong to the family of Caliciviridae, which includes the Norwalk virus—a common cause of gastroenteritis in humans—and consists of a single, plus-strand RNA genome of approximately 7.2 kb without an envelope (Fig. 1). The virus contains at least three open reading frames encoding viral proteins against which antibodies are made on exposure. These antibodies, especially those against the capsid protein derived from the second open reading frame2 and a protein of unknown function derived from the third open reading frame, are detected by currently available serologic assays. Retrospective studies on stored sera of past epidemics of viral hepatitis in Mexico, Africa, Afghanistan, Pakistan, India, Bangladesh, Burma, Nepal, and Borneo have revealed that all were caused by strains of hepatitis E. In addition, hepatitis E was found to be responsible for the hepatitis epidemic in the southern part of Xinjiang, China, in which 120,000 persons became infected between September 1986 and April 1988.3 Hepatitis E predominantly affects young adults (15 to 40 years old). The symptoms of hepatitis E are similar to those of hepatitis A. Frequently, a prodrome consisting of anorexia, nausea, low-grade fever, and right upper abdominal pain is present 3 to 7 days before jaundice develops. Aminotransferase levels peak (usually between 1,000 and 2,000 U/L) near the onset of symptoms; bilirubin levels (10 to 20 mg/dL) peak later. Jaundice usually resolves after 1 to 2 weeks. In about 10% of cases, the disease is fulminant—especially in pregnant women, among whom mortality rates as high as 20% due to hemorrhagic and thrombotic complications have been reported. No evidence has suggested that hepatitis E can cause chronic infection. Transmission is by the fecal-oral route, predominantly through fecally contaminated drinking water supplies. In addition, however, preliminary reports have suggested transmission of the hepatitis E virus through blood transfusions. Volunteer studies confirmed the presence of the virus in serum and feces before and during clinical disease.4 The virus is shed into feces approximately 1 week before symptoms develop. The incubation period varies from 2 to 9 weeks (mean duration, approximately 45 days). Until now, a few reports had described symptomatic hepatitis E acquired in Europe;5, 6 all patients with symptomatic hepatitis E in the United States were travelers returning from Mexico, Africa, or the Far East, in whom hepatitis E developed after their return home.7 In this issue of the Mayo Clinic Proceedings (pages 1133 to 1136), Kwo and associates describe a case of hepatitis E in a man who had not left the United States during the previous 10 years. Specific serologic tests for hepatitis E virus IgG (enzyme immunoassays and a fluorescent antibody blocking assay) and IgM8 (US strain-specific enzyme-linked immunosorbent assay with use of synthetic polypeptides deduced from the viral genome, as shown in Figure 1), developed at Abbott Laboratories (IgG and IgM) as well as at the Centers for Disease Control and Prevention (IgG), were used to prove that the patient indeed had acute hepatitis E. Researchers at Abbott Laboratories have prepared a report that describes most of the viral genome in this patient (Fig. I).8 Their results are interesting because this strain from the United States differs considerably from hepatitis E strains isolated in Mexico, Burma, Pakistan, or China. Furthermore, the sequence of the US strain is highly homologous (98% and 94% homology at the amino acid level to the second and third open reading frames, respectively) to a recently isolated hepatitis E strain from American swine.9 This finding suggests that, in the United States, hepatitis E is a zoonosis with the swine population as one of its hosts. This relationship would confirm earlier studies in Asia, where swine were also found to carry variants of the hepatitis E virus.10 Why are these two recent discoveries important for medicine in the United States? First, other sporadic, locally acquired cases of acute hepatitis may be caused by hepatitis E. Second, these back-to-back discoveries strongly suggest that a common natural host for hepatitis E is present in countries with more moderate climates. Because swine do not seem to experience any symptoms associated with infection and because symptoms in humans can be minor or absent, we now may also have an explanation for the 1 to 2% of positive hepatitis E serologic results in blood donors in the United States,11 Netherlands,12 and Italy,6 countries with large swine staples. Clearly, more research needs to be done to confirm this hypothesis. Third, in countries with more moderate climates, hepatitis E may often result in a subclinical infection. Is this variation in manifestation due to less virulent strains, and do sequence variations determine virulence? Fourth, swine may be used as an animal model for study of the disease as well as vaccine development.

Urinary incontinence — the loss of bladder control — is a common and often embarrassing problem. The severity ranges from occasionally leaking urine when you cough or sneeze to having an urge to urinate that's so sudden and strong you don't get to a toilet in time. If urinary incontinence affects your daily activities, don't hesitate to see your doctor. For most people, simple lifestyle changes or medical treatment can ease discomfort or stop urinary incontinence

Chronic Renal Failure

Keratectomy with Amniotic Membrane Graft Eye

Gastrointestinal GI Drug Delivery

Pancreatic cysts are saclike pockets of fluid on or in your pancreas, a large organ behind the stomach that produces hormones and enzymes that help digest food. Most pancreatic cysts aren't cancerous, and many don't cause symptoms. They're typically found during imaging testing for another problem. Some are actually noncancerous (benign) pockets of fluids lined with scar or inflammatory tissue, not the type of cells found in true cysts (pseudocysts). But some pancreatic cysts can be or can become cancerous. Your doctor might take a sample of the pancreatic cyst fluid to determine if cancer cells are present. Or your doctor might recommend monitoring a cyst over time for changes that indicate cancer.

Congestive Heart Failure 3D Animation

Understanding the adrenergic receptors is fundamental to a solid grasp of adrenergic pharmacology!

Signs and symptoms of colon cancer include: A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool, that lasts longer than four weeks Rectal bleeding or blood in your stool Persistent abdominal discomfort, such as cramps, gas or pain A feeling that your bowel doesn't empty completely Weakness or fatigue Unexplained weight loss Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they'll likely vary, depending on the cancer's size and location in your large intestine.

Laparoscopic Suture Repair of Bowel

Demonstration of vertical mattress suturing technique for laceration repair or wound closure in the operating room.

Demonstration of simple interrupted suturing technique for laceration repair.

How female-to-male gender reassignment surgery works

Nose cautery can help prevent nosebleeds. The doctor uses a chemical swab or an electric current to cauterize the inside of the nose. This seals the blood vessels and builds scar tissue to help prevent more bleeding. For this procedure, your doctor made the inside of your nose numb.

Pediatric Neurological Examination Introduction