AIDS is the abbreviation for acquired immune deficiency syndrome, a deficiency of the immune system due to infection with the human immunodeficiency virus (HIV). The interval between infection and development of AIDS is highly variable. Without treatment, around half of those individuals infected will develop AIDS within eight to nine years. In about one in ten cases, however, progression to AIDS is very slow, taking up to 20 years or longer. Illness and death from AIDS is a major health problem worldwide, and there is, as yet, no cure or vaccine.

AIDS METHODS OF TRANSMISSION

HIV is transmitted in body fluids such as semen, blood, vaginal secretions, and breast milk. Major methods of transmission are sexual contact (vaginal, anal or oral), blood-to-blood (via transfusions, or needle-sharing in drug users), and mother-to-fetus. HIV has also been transmitted through blood products given to treat haemophilia, kidney transplant, and artificial insemination by donated semen; but improved screening has greatly reduced these risks. HIV is not spread by everyday contact, such as hugging or sharing crockery.

EFFECTS OF THE VIRUS

The virus enters the bloodstream and infects cells with a particular receptor, called the CD4 receptor, on their surface. These cells include a type of white blood cell called a CD4 lymphocyte (a T-lymphocyte with a CD4 receptor), that is responsible for fighting infection, and cells in other tissues such as the brain. The virus reproduces with the infected cells, which then die, releasing more virus particles into the blood. If the infection is left untreated, the number of CD4 lymphocytes falls, resulting in greater susceptibility to certain infections and some types of cancer.

AIDS SYMPTOMS AND SIGNS

Some people experience a short-lived illness similar to infectious mononucleosis when they are first infected with HIV. Many individuals have no obvious symptoms but are, nevertheless, infectious. After the initial illness, many people remain well. Some may suffer from enlarged lymph nodes, muscle pain, and excessive swating.  Severe bacterial infections, such as pneumonia, are common. Later, vague complaints, such as weight loss, fevers, sweats, or unexplained diarrhoea (known as AIDS-related complex) may herald the development of AIDS.

Other features of infection with HIV include skin disorders such as seborrhoeic dermatitis, and a variety of viral, fungal and bacterial infections, such as persistent herpes simplex infections, oral candidiasis (thrush), tubercolosis, and shigellosis. HIV may also affect the brain, causing a variety of neurological disorders, including dementia.

Certain conditions, known as AIDS-defining illnesses, mark the development of full-blown AIDS. These include cancers (Kaposi’s sarcoma and lymphoma of the brain), and various infections (pneumocystis pneumonia, tubercolosis, human papillomavirus, cytomegalovirus infection, toxoplasmosis, diarrhoea due to Criptosporidium or Isospora, candidiasis, disseminated strongyloidiasis, and cryptococcosis), many of which are described as opportunistic infections.

AIDS DIAGNOSIS

Confirmation of HIV infection involves testing a blood sample for the presence of antibodies to HIV (HIV test), which may not develop for three months after initial infection. The condition is monitored using blood tests that measure the number of CD4 lymphocytes in the blood or by measuring viral load (the amount of virus detectable in the blood). Diagnosis of full-blown AIDS is based on a positive HIV test along with the presence of an AIDS-defining illness. Sometimes people only become aware that they have HIV when they develop an AIDS-defining illness and then have an HIV test.

AIDS TREATMENT AND OUTLOOK

The treatment of HIV infection can be divided into treatment for the HIV infection itself and treatment of the conditions and complications that are associated with HIV/AIDS.

Treatment of the infection with a combination of antiretroviral drugs can slow progress of the disease and may prevent the development of full-blown AIDS by reducing the amount of viruses in the bloodstream. The two main types of antiretroviral drugs are reverse transcriptase inhibitors, such as zidovudine, and protease inhibitors, such as indinavir. Both groups of drugs work by disrupting replication of HIV inside cells. Several drugs are usually used in combination in a regimen known as highly active antiretroviral therapy, or HAART. The emergence of resistant strains of HIV has led to  the development of a new group of drugs called fusion inhibitors (such as enfuvirtide), which work by interfering with the entry of the virus into cells. The mainstay of treatment for HIV/AIDS-related illnesses consists of antibiotics, antifungals, and other anti-microbial drugs to treat specific infections as they develop.

Since the introduction of combination drug therapy, deaths from AIDS in the developed world have fallen dramatically. However, such therapy is not a cure and HIV-infected people are still infectious even when the infection is being controlled successfully with drug treatment. Therefore, the most effective strategy for defeating HIV/AIDS remains prevention of infection.

PREVENTION OF INFECTION

The risk of infection can be reduced by practicing safer sex and by intravenous drug users not sharing needles. There is a small risk to health workers handling infected needles (needlestick injury) or blood products, but this can be minimized by the adoption of safe practices in the workplace.

Source: A-Z family medical encyclopedia by BMA

Popularity: 5% [?]