An infectious disease: HIV/AIDS

What is it?
HIV is the human immunodeficiency virus which causes the illness AIDS. HIV is a slow retrovirus, which means that it takes years to show symptoms and that it invades white cells in the blood by literally writing the structure of itself backwards (retro) into them and reproducing itself inside the cells. White cells produce antibodies that are the body’s main defence against disease and without them the body becomes the target of everyday infections and cell changes that cause cancers. This is what happens to someone suffering from AIDS.
There is some controversy over the source of the disease. Some people believe that it is manmade and was produced by a chemical weapons laboratory or be medical research gone wrong. However, the generally accepted view is that it evolved in sub-Saharan Africa, crossing over from the chimpanzee population in contaminated meat or be a bite from a pet, possibly in the 1930s. Some scientists have suggested that the virus was present in the human population of central Africa fo a long time but on a local scale. Developments in the 20th century such as international travel, blood trnsfusions and intravenous drug use brought it onto the world stage and produced a pandemic.
The spread of HIV
Today the virus is spread through the following ways:
· Exchange of bodily fluids during sexual intercourse
· Contaminated needles in intravenous drug use (IDU)
· Contaminated blood transfusions
· From mother to child during pregnancy
Evidence shows that the disease started in small high-risk groups such as gay men, drug users and prostitutes, and then spread into the population as a whole. this meant that in the early stages of the disease in developed countries, AIDS was regarded by many as a ‘gay plague’. The heterosexual community took little notice of it and education about safe sex was diregarded. In developing countries, mainly in Africa, the transfer of the virus was more commonly through heterosexual sex, but this was not known in most of the developed world.
Three distinct patterns of spread developed:
Pattern 1: covers areas which began to see a spread of HIV in the late 1970s, first among the homosexual, bisexual and drug-using communities and later in the general opulation. This includes North America, western Europe, Australia and some parts of Latin America.
Pattern 2: covers those countries where the spread has been essentially through heterosexual contact. this includes the bulk of sub-Saharan Africa, where more women than men are infected ( in the proportion of (60:40). In 2005 over 0.5 million children were infected as a result of mother-to-child transmission.
Pattern 3: coveres those regions where the disease appeared later (in the 1980s) and was bought in by travellers and sometimes by blood imported for transfusions. This includes eastern Europe (including the former USSR), Asia, the middle East and north Africa.

By 2006, it was estimated that over 39 million people worldwide were living with HIV or full-blown AIDS. In every global region the number of poeple living with HIV is rising. The steepest rises have been in east Asia, central Asia and eastern Europe, but the situation is most serious in sub-Saharan Africa. Over 62% of people living with HIV/AIDs (24.7 million people) in 2006 were in the countries of sub-Saharan Africa. It has been estimated that 6% of the adult poplulation of sub-Saharan Africa is HIV-positive. The area has over 13 million infected women, which represents 76% of all women in the world living with HIV. Ten countries have 10% or more of their adult population infected@ Swaziland (33%), Botswana (24%), Lesotho (23%), Malawi, Mozambque, Namibia, South Africa, Zambia, Central African Republic and Zimbabwe. The United Nations (UN) has estimated that by 2020, 70 million people in the wolrd will have died from AIDS.