Definitions beginning with the
Word H

• Hepatitis A
  Hepatitis A (formerly known as infectious hepatitis) is an acute infectious disease of the liver caused by the hepatitis A virus (HAV), which is most commonly transmitted by the fecal-oral route via contaminated food or drinking water. Every year, approximately 10 million people worldwide are infected with the virus. The time between infection and the appearance of the symptoms, (the incubation period), is between two and six weeks and the average incubation period is 28 days. In developing countries, and in regions with poor hygiene standards, the incidence of infection with this virus is high and the illness is usually contracted in early childhood. HAV has also been found in samples taken to study ocean water quality. Hepatitis A infection causes no clinical signs and symptoms in over 90% of infected children and since the infection confers lifelong immunity, the disease is of no special significance to the indigenous population. In Europe, the United States and other industrialized countries, on the other hand, the infection is contracted primarily by susceptible young adults, most of whom are infected with the virus during trips to countries with a high incidence of the disease.
• Hepatitis B
  Hepatitis B is a disease caused by hepatitis B virus (HBV) which infects the liver of hominoidae, including humans, and causes an inflammation called hepatitis. Originally known as "serum hepatitis", the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China. About a third of the world population, more than 2 billion people, have been infected with the hepatitis B virus. This includes 350 million chronic carriers of the virus. Transmission of hepatitis B virus results from exposure to infectious blood or body fluids containing blood. The acute illness causes liver inflammation, vomiting, jaundice and—rarely—death. Chronic hepatitis B may eventually cause liver cirrhosis and liver cancer—a fatal disease with very poor response to current chemotherapy. The infection is preventable by vaccination.
• Hepatitis C
  Hepatitis C is an infectious disease affecting the liver, caused by the hepatitis C virus (HCV). The infection is often asymptomatic, but once established, chronic infection can progress to scarring of the liver (fibrosis), and advanced scarring (cirrhosis) which is generally apparent after many years. In some cases, those with cirrhosis will go on to develop liver failure or other complications of cirrhosis, including liver cancer. The hepatitis C virus (HCV) is spread by blood-to-blood contact. Most people have few, if any symptoms after the initial infection, yet the virus persists in the liver in about 85% of those infected. Persistent infection can be treated with medication, peginterferon and ribavirin being the standard-of-care therapy. 51% are cured overall. Those who develop cirrhosis or liver cancer may require a liver transplant, and the virus universally recurs after transplantation.
• Homeopathy
  Homeopathy (also spelled Homoeopathy or Homœopathy) is a form of alternative medicine, first proposed by German physician Samuel Hahnemann in 1796, that treats patients with heavily diluted preparations which are thought to cause effects similar to the symptoms presented. Homeopathic remedies are prepared by serial dilution with shaking by forceful striking, which homeopaths term succussion, after each dilution under the assumption that this increases the effect of the treatment. Homeopaths call this process potentization. Dilution often continues until none of the original substance remains. Apart from the symptoms of the disease, homeopaths use aspects of the patient physical and psychological state in recommending remedies. Homeopathic reference books known as repertories are then consulted, and a remedy is selected based on the totality of symptoms. Homeopathic remedies are considered safe, with rare exceptions. Some homeopaths have, however, been criticized for putting patients at risk with advice to avoid conventional medicine such as vaccinations, anti-malarial drugs, and antibiotics. In many countries, the laws that govern the regulation and testing of conventional drugs do not apply to homeopathic remedies.
• Humoral Immune Response
  The Humoral Immune Response (HIR) is the aspect of immunity that is mediated by secreted antibodies (as opposed to cell-mediated immunity, which involves T lymphocytes) produced in the cells of the B lymphocyte lineage (B cell). B Cells (with co-stimulation) transform into plasma cells which secrete antibodies. The co-stimulation of the B cell can come from another antigen presenting cell, like a dendritic cell. This entire process is aided by a CD 4 T-helper 2 cell. Secreted antibodies bind to antigens on the surfaces of invading microbes (such as viruses or bacteria), which flags them for destruction. Humoral immunity is so named because it involves substances found in the humours, or body fluids.