HIV / AIDS

Acquired immunodeficiency syndrome (AIDS) is an immunosuppressed state, caused by infection with the human immunodeficiency virus (HIV). It is characterised by opportunistic infections, neoplasms and neurological manifestations. 

Pathogenesis

AIDS is caused by the HIV retrovirus which infects the CD4+ T-cells and macrophages. Following a period of clinical latency, viral replication within these cells leads to lysis of the CD4+ cells, and macrophage driven transport of the virus into the central nervous system. This results in profound immunosuppression involving primarily the cell-mediated immunity, and in CNS disease, respectively ¹.

The main modes of transmission are sexual contact, via blood (e.g. intravenous drug use or blood transfusions) and vertical transmission from HIV infected mothers.

Epidemiology

According to the United Nations programme on HIV / AIDS (UNAIDS)², it is estimated that worldwide in 2008:

• 33.4 million people were living with HIV, of whom 2.1 million were children under 15 years.
• 2 million people died of AIDS-related conditions, of whom 430,000 million were children under 15 years.
• 2.7 million people became newly infected with HIV.

Clinical presentation

Following infection with the HIV virus, individuals experience a non-specific, flulike seroconversion illness, manifesting as fever, sore throat, lymphadeonopathy, skin rash and malaise. This is followed by an asymptomatic incubation period, lasting several years. 

The diagnosis of AIDS rests on the progression to clinical or serological evidence of immunodeficiency. According to the US CDC definition, one has AIDS if he/she is infected with HIV and presents with either:

• a CD4+ T-cell count below 200 cells/µl (or a CD4+ T-cell percentage of total lymphocytes of less than 14%).

• at least one of the AIDS defining illnesses ³.

Clinical and radiological manifestations

In every body system, there are numerous conditions associated with AIDS. The following articles will attempt to summarise the more common ones:

• CNS manifestations of AIDS
• pulmonary manifestations of AIDS
• cardiovascular manifestations of AIDS
• gastrointestinal manifestations of AIDS
• genitourinary manifestations of AIDS
• musculoskeletal manifestations of AIDS

See also

• HIV associated neoplasms
• AIDS embryopathy