HEPATITIS B ANTIGEN: REGIONAL VARIATION IN INCIDENCE AND SUBTYPE RATIO IN THE AMERICAN RED CROSS DONOR POPULATION1
R. Y. DODD, P. V. HOLLAND, LOUISA Y. NI, HOLLY M. SMITH and T. J. GREENWALT
Address for reprint requests: Mr. R. Y. Dodd, American Red Cross, Blood Research Laboratory, 9312 Old Georgetown Road, Bethesda, Maryland 20014
Dodd, R. Y. (Amer. Nat. Red Cross, Blood Research Lab., 9312 Old Georgetown Rd., Bethesda, Md. 20014) P. V. Holland, L. Y. Ni, H. M. Smith, and T. J. Greenwalt. Hepatitis B antigen: Regional variation in incidence and subtype ratio in the American Red Cross donor population. Am J Epidemiol 97: 111–115, 1973.—A study of 2,596,118 Red Cross blood donations taken between April and December 1971 has established 0.104% as the national incidence of hepatitis B antigen (HBAg) antigenemia among volunteer blood donors. Considerable and significant variations in incidence have been demonstrated both locally and on a broad regional basis. In addition, the national value for the ratio of the HBAg subtype ad to HBAg subtype ay was found to be 5.8:1; again with considerable regional variation. In general, northern regions demonstrated a low incidence of HBAg whereas high incidences were found in the southeast, or in densely populated urban areas. Low ad: ay ratios were noted in two northeastern states and in the northwestern region of the U.S. In the absence of detailed information on the geographic variation of donor populations detailed analysis of the basis for these variations is not possible.
Australian antigen; blood donors; hepatitis associated antigen; hepatitis B
An antigen is a substance that prompts the generation of antibodies and can cause an immune response. The word originated from the notion that they can stimulate antibody generation. We now know that the immune system does not consist of only antibodies. The modern definition encompasses all substances that can be recognized by the adaptive immune system. In the strict sense, immunogens are those substances that elicit a response from the immune system, whereas antigens are defined as substances that bind to specific antibodies. Not all antigens produce an immunogenic response, but all immunogens are antigens (Immunobiology, Janeway and Travers, 1994).
Antigens are usually proteins or polysaccharides. This includes parts (coats, capsules, cell walls, flagella, fimbrae, and toxins) of bacteria, viruses, and other microorganisms. Lipids and nucleic acids are antigenic only when combined with proteins and polysaccharides. Non-microbial exogenous (non-self) antigens can include pollen, egg white, and proteins from transplanted tissues and organs or on the surface of transfused blood cells.
Hepatitis B is a disease caused by HBV hepatitis B virus 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's 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 B virus is an hepadnavirus—hepa from hepatotrophic and dna because it is a DNA virus—and it has a circular genome composed of partially double-stranded DNA. The viruses replicate through an RNA intermediate form by reverse transcription, and in this respect they are similar to retroviruses. Although replication takes place in the liver, the virus spreads to the blood where virus-specific proteins and their corresponding antibodies are found in infected people. Blood tests for these proteins and antibodies are used to diagnose the infection.
Influenza A virus subtype H1N1, also known as A(H1N1), is a subtype of influenzavirus A and the most common cause of influenza (flu) in humans. Some strains of H1N1 are endemic in humans, including the strain(s) responsible for the 1918 flu pandemic which killed 50-100 million people worldwide. Less virulent H1N1 strains still exist in the wild today, worldwide, causing a small fraction of all influenza-like illness and a large fraction of all seasonal influenza. H1N1 strains caused roughly half of all flu infections in 2006. Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).
In March to June of 2009, thousands of laboratory-confirmed infections and a number of deaths were caused by an outbreak of a new strain of H1N1.