It is called a syndrome because AIDS consists of the appearance of one or several diseases. These diseases develop because the virus slowly, continually and progressively destroys the body’s self-defence system –the immune system.
Acquired Immunodeficiency Syndrome, or AIDS, is the severest form of the infection caused by the Human Immunodeficiency Virus, or HIV.
The immune system
The immune system is a set of defence mechanisms which the human body uses to protect against infection. HIV brings about the slow, continuous and progressive destruction of part of the immune system, which in turn triggers its failure and eventually produces the illness known as AIDS. Treatment prevents this destruction and furthermore, when administered in early stages of the disease, can help restore the body’s defences in the majority of patients.
The virus and how it affects the body
HIV belongs to the retrovirus family (Retroviridae). They are given this name because they are able to convert their genetic material, their RNA (ribonucleic acid), into DNA (deoxyribonucleic acid). HIV targets the CD4 lymphocyte, which is responsible for coordinating the body’s defences. This means HIV is a very aggressive virus and if left untreated it will leave the body vulnerable to different pathological agents.
It is very common?
According to UNAIDS, 37 million people were infected with HIV at the end of 2014. Since the year 2000, 38 million people have been infected with HIV and 25 million have died from AIDS.
Despite these data, the situation has improved in recent years. The number of new infections reported went from 3 million in 2000 down to 2 million by 2014, and in the same period the number of AIDS-related deaths dropped from 2 million to 1.2 million. The improvement is due to the increase in the number of patients receiving treatment in Africa, rising from 500,000 in 2002 up to 16 million in 2015. This equates to 41% of adults, 32% of children and 70% of pregnant women who are currently receiving treatment for their condition.
In Western society, there are currently 2.5 million people infected with HIV and 80,000 new infections are reported each year, of which over 3,000 are in Spain. Therefore, despite new treatments being available, the epidemic is not under control and in the last 10 years the number of new infections has not shown any significant variation, suggesting that new measures need to be adopted in order to control its spread.
How is the virus transmitted?
HIV cannot live for very long outside a host body and therefore it requires direct physical contact with the infected person in order for it to be transmitted. The most typical means of infection are:
Blood transmission. Blood (including menstrual blood) from an infected person will carry the virus. Thus the infection can be acquired when the blood of an affected person comes into contact with the bloodstream of a healthy one.
Sexual transmission. The virus is present in semen, vaginal fluid and in the mucus of the anus and vagina. These fluids can enter the body via open wounds or through genital mucous membranes. Therefore, all activities involving these fluids imply the risk of transmission. Male and female condoms prevent the transmission of HIV and the majority of sexually transmitted infections.
Vertical transmission. Pregnant women who are infected with HIV can transmit the virus to their child at different stages: while the foetus is in the uterus, during birth or during breastfeeding.
The initial infection with HIV does not usually present any specific symptoms. However in some cases it can cause flu-like symptoms such as fever, swollen neck glands, general discomfort and/or skin rash. Most patients do not present any symptoms at all in the chronic or latency stage. The final stage is characterised by a progressive deterioration of the patient’s general condition, appetite loss, weight loss, fever and diarrhoea, and subsequently opportunistic infections, malignant tumours and neurological disorders appear.