AIDS

Human Immunodeficiency Virus (HIV)
HIV (the human immunodeficiency virus) infects the immune system and causes severe immune deficit. HIV is a lentivirus (family of retroviruses) that mainly targets the white blood cells (CD4 lymphocytes). If no antiretroviral treatment is administered, the destruction of the patient's immune system typically occurs in several phases: rapid and transient decline in the number of CD4 lymphocytes over the first year; slow decrease of these lymphocytes taking place over anywhere from a few months to more than 10 years; onset of full-blown AIDS, followed by the destruction of all CD4 lymphocytes. The clinical symptoms that accompany AIDS primarily include infectious complications and cancers brought on by the deficit in the immune system.

Impact on public health

Since the epidemic began (at the end of the 1970s or in the early 1980s, depending on the country), the number of persons living with HIV has increased in a manner that is both alarming and very uneven. In 2003, 40 million people were carriers of the virus; 27 million of them were living in sub-Saharan Africa and 6 million in Southern and Southeast Asia. In 2003, five million people were newly infected, the equivalent of 14,000 each day. Three and one half million children under age 15 are living with HIV. AIDS is the leading cause of death among the 15-59 age group worldwide. Nearly 80% of the three million AIDS-related deaths in 2003 occurred in sub-Saharan Africa, where AIDS kills nearly 5,000 men and women and 1,000 children each day.
In terms of treatment, combinations of antiretroviral drugs (triple drug therapy) have changed the course of the disease, but they remain largely inaccessible, primarily for economic reasons, in the countries most affected by the epidemic. In an effort to reduce the cost of some of their products in developing countries, companies in the pharmaceutical and diagnostics industries have recently entered into agreements such as the one developed by the William J. Clinton Foundation (press release), to which bioMérieux will contribute.

Strategies to prevent HIV infection are often difficult to implement but nonetheless represent a decisive factor in efforts to stop the spread of the AIDS pandemic.

Diagnosis

Clinical signs: Primo-infection is asymptomatic or gives rise to non-specific signs of infection. As the disease evolves, patients may develop infectious complications and tumors. When a patient's immune system becomes very weakened, specific infections known as opportunistic infections (tuberculosis, CMV, toxoplasmosis, etc.) are likely to develop, as well as certain kinds of tumor (in particular, Kaposi's sarcoma).

Biological analyses: The detection of HIV antibodies confirms of HIV infection (seropositivity). For many years, the only biological means to monitor the evolution of infection was to count CD4 lymphocytes. Today, in countries where the medical infrastructure is sufficiently sophisticated, it is possible to measure a patient's viral load, a test that is essential to evaluate the efficacy of an antiretroviral treatment and adjust it if the virus develops resistance to the molecules that are being used.