AIDS

QUICK OVERVIEW

What is AIDS?
• AIDS (Acquired Immune Deficiency Syndrome) results from an infection by the HIV, a retrovirus which attacks the immune system. AIDS itself is the final stage of the infection.
• In 2007, the UN estimated that 33,2 million persons around the world were HIV-positive, and that the disease had caused 2,1 million deaths during the year.
• Although the outbreak is present globally, it is particularly virulent in Russia, Sub-Saharan Africa, South-East Asia and Latin America.



Immunity
• Immunity mechanisms remain widely unknown for the time being. As of today, there is no known acquired immunity against AIDS.

TRANSMISSION

Vector
• HIV is transmitted through the contact with infected blood (injection or transfusion of infected blood, sharing of unsterilized equipment, e.g. needles, etc.), through unprotected intercourse with an HIV-positive partner, and between mother and child during pregnancy, at birth or through breastfeeding.



Incubation period
• The incubation period varies from three weeks to six months on average. Symptoms often appear much later, several years or even decades after the initial infection.



High-risk populations
• Certain high-risk behaviors (drug abuse, sharing of needles, unprotected intercourse, multiple partners, etc.) favor the transmission of the HIV; health professionals may also be more exposed to the virus.

PREVENTION

• Prevention rests upon the systematic use of condoms during sex and the refusal of any transfusion or injection made in non-sterile conditions. When travelling, it is also recommended to avoid any practice implying the use of sharp instruments, such as tattoos.
• Mosquitoes are not a vector of the virus, neither are saliva, sweat, tears or urine. The skin constitutes a barrier to the virus.
• There is no immunization against HIV. Immediately after a possible contamination (unprotected intercourse, condom breakage, wound due to a bloody object...), it is possible to take antiretroviral post-exposure prophylaxis to reduce the risk of infection. This treatment can be obtained in hospitals or testing sites, within 48 hours after the posible infection. However, it is not efficient in 100% of the cases and may not be available in developing countries.

SYMPTOMS

• There are three main phases in the propagation of the virus.
• The primary infection, or sero-conversion phase, occurs four to eight weeks after the contamination and is generally asymptomatic. 30 to 60% of the people develop a flu-like syndrome (sore throat, headache, mild fever, muscle and joint pain...). Symptoms usually last one to four weeks.
• The asymptomatic latent phase, or "silent phase", may last several years. In that phase, infected persons usually display no symptoms and may not be aware that they are carrying the virus. The silent phase is characterized by a progressive deterioration of immune defenses, which may lead to occasional fever, shingles, swelling of the lymph nodes, infections and moderate weight loss.
• The final phase, or AIDS phase, usually occurs after a decade and is characterized by the apparition of opportunistic diseases which may affect the nervous system (memory loss, confusion, toxoplasmosis...), the respiratory tract (pneumonia, tuberculosis...), the digestive system (Candida, diarrhea, nausea), etc. The patient usually suffers from an important weight loss, feels persistently tired and his lymph nodes are severely swollen. Skin lesions, notably Kaposi's sarcomas, are frequent.
• Tuberculosis remains a leading cause of death among people living with HIV, who are also twice as likely to have multidrug-resistant tuberculosis as people who are HIV-negative.

TREATMENT

• The use of antiretroviral therapy slows down the progression of the virus but does not allow for a complete recovery. This treatment involves a number of side effects and constraints that may prove hard to manage on a daily basis; it remains however necessary and somehow effective.