Human immunodeficiency virus (HIV) is a virus infecting humans, and is responsible for acquired immunodeficiency syndrome (AIDS).1 HIV belongs to the retrovirus family and possesses the ability to reverse-transcribe its single-strand RNA genome to form double-strand DNA, which can then integrate into the genome of the host cell.1 There are two types of HIV; HIV-1 and HIV-2. HIV-1 is the most common type, affecting the majority of people living with HIV around the world.1
The transmission of HIV requires contact with a body fluid that contains the virus or infected cells. This can occur through; sexual contact, blood transfusion, sharing of contaminated equipment (syringe), through the placenta during childbirth and through breastfeeding.1 The viral particles present in these body fluids recognise specific receptors (mainly CD4+ lymphocytes) on the surface of cells destined to be infected.1
The HIV infection is characterised by progressive loss of CD4+ lymphocytes, leading to severe immunodeficiency after a varying period of time.2 The average time between initial infection and the onset of the clinical signs of AIDS is to about 8-10 years, but the time is variable between individuals, and depends on a complex interaction between virus and host.2
AIDS is now one of the largest pandemics and has become a global health problem because the disease remains incurable.3 AIDS was identified in 1981, and the virus that causes HIV was isolated for the first time in 1983.3 Since then, the disease has spread in waves in different parts of the world.4 In 2009, according to the World Health Organisation data, more than 33 million people were living with the HIV virus.5
AIDS continues to take a heavy toll around the world, particularly in sub-Saharan Africa, and its incidence is increasing in some countries such as; China, India and parts of Eastern Europe.4 Information campaigns on sexual risk behaviours, and awareness campaigns on use of condoms, remain the best prevention against STIs such as AIDS.6
1. Beers M.H. et al. The Merck manual of medical information. Merck research laboratories. Second home edition. 2003, 1168-1184.
2. de Oliveira Silva M. et al. Acute HIV infection with rapid progression to AIDS. Brazilian Journal of Infectious Diseases. May-June 2010 ; 14 (3) : 291-293.
3. Levin B.R et al. Epidemiology, Evolution, and Future of the HIV/AIDS Pandemic. Emerging Infectious Diseases. June 2001 ; 7 (3) : 505-511.
4. Fauci A.S. HIV and AIDS: 20 years of science. Nature Medicine. July 2003 ; 9 (7) : 839-843.
5. World Health Organization. Global summary of the HIV/AIDS epidemic. WHO and UNAIDS. December 2009 : available online.
6. Genuis S.J. et al. Managing the sexually transmitted disease pandemic: A time for reevaluation. American Journal of Obstetrics and Gynecology. October 2004 ; 191 (4) : 1103-1112.
Hepatitis can be caused by many different things including viral infections, parasites, bacteria, chemicals, autoimmunity, drugs or alcohol. Of these, viral infection is the most common cause of chronic (long-term) hepatitis, which can lead to severe liver damage including cirrhosis and liver cancer.
Hepatitis B and C viruses (HBV and HCV) are among the world’s most common infectious pathogens. It is estimated that 500 million people – 1 in 12 of the global population – are chronically infected with one or both of these viruses.1,2 The majority of these people live in the developing world and many of them are unaware that they are infected. Chronically infected patients are at increased risk of developing cirrhosis, hepatic decompensation and hepatocellular carcinoma (HCC), which together account for more than 1 million deaths annually.3
The hepatitis B virus is a resilient virus present in all bodily fluids of infected individuals. It is resistant to breakdown and able to survive outside the body. It can be transmitted effectively through contact with infected bodily fluids in the same way as HIV. However, HBV is 50–100 times more infectious than HIV.
Screening for HBV and HCV infection is crucial, not only to detect patients who may require treatment to reduce the risk of progression to severe sequelae, but also to reduce transmission rates.
The primary objective of therapy for chronic HBV is to achieve control of viral replication and halt disease progression/improve liver histology. This will decrease pathogenicity and infectivity and thereby stop or reduce hepatic necroinflammation.
Chronic hepatitis C infection may result in severe liver damage leading to liver failure, HCC and death. As a consequence, therapeutic intervention can arrest, and perhaps even reverse, the disease before irreversible liver damage occurs.
Enter the Hepatitis B and C Knowledge Centre
What’s in the Hepatitis B and C Knowledge Centre?
References
1. World Health Organization. World Health Organization Hepatitis B Fact Sheet. 1998.
2. World Hepatitis Alliance. www.aminumber12.org
3. Lai CL, Ratziu V, Yuen MF, Poynard T. Viral hepatitis B. Lancet 2003;362:2089–94
An Animations Explaining the Mechanism by which the HIV Virus works
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