Human Immunodeficiency Virus
Infection by the Human Immunodeficiency Virus (HIV) first appears as a transient flu-like illness. There then follows a variable period of good health which may last many years. The HIV virus has tropism for lymphocytes expressing CD4 antigen (T helper cells).
As the disease progresses there is a steady decline in the number of CD4+ lymphocytes in the peripheral blood.
Patients frequently develop chronic lymphadenopathy and at a later stage typically develop the signs and symptoms of chronic infections often with atypical organisms such as fungi, mycobacteria, and Pneumocystis carinii.
- A proportion of patients with HIV infection develop malignancies, particularly Kaposi’s sarcoma, aggressive non-Hodgkin’s lymphoma and Hodgkin’s disease. The lymphomas frequently contain the EBV virus.
- Patients with acquired immunodeficiency syndrome (AIDS) are often anemic and this can be exacerbated by treatment and cotrimoxazole (Septrin) used in prophylaxis for pneumocystis.
- The neutrophil count may be reduced and in some cases this deficiency is autoimmune in origin. Immune thrombocytopenia is more common and may necessitate splenectomy.
- The bone marrow in AIDS patients displays non-specific abnormalities including hypercellularity, megaloblastoid erythropoiesis, myeloid dysplasia, lymphoid aggregates, eosinophilia, plasmacytosis and increased reticulin.
Screening for human immunodeficiency virus (HIV) infection is paramount since infected individuals may remain asymptomatic for years while the infection progresses.
- HIV infection is diagnosed by a standard serological test, and progression can be monitored by regular measurement of CD4+ cells in the blood.
- Secondary testing that may be performed to assist with diagnosis or staging includes Viral culture, Lymph node biopsy, Proviral DNA polymerase chain reaction (PCR) and Genotyping of viral DNA/RNA.
- In the presence of fever, thorough clinical examination and detailed investigations must be carried out to find the cause.
- A bone marrow examination may occasionally be the most direct way to detect mycobacterial infections and lymphomas.
The treatment of human immunodeficiency virus (HIV) disease depends on the stage of the disease and any concomitant opportunistic infections. In general, the goal of treatment is to prevent the immune system from deteriorating to the point that opportunistic infections become more likely.
Standard antiretroviral therapy (ART) is the principal method for preventing immune deterioration. In addition, prophylaxis for specific opportunistic infections is indicated in particular cases.
ART consists of the combination of antiretroviral (ARV) drugs to maximally suppress the HIV virus and stop the progression of HIV disease. ART also prevents onward transmission of HIV. Huge reductions have been seen in rates of death and infections when use is made of a potent ARV regimen, particularly in early stages of the disease.
WHO recommends ART for all people with HIV as soon as possible after diagnosis without any restrictions of CD4 counts. It also recommends pre-exposure prophylaxis to people at substantial risk of HIV infection as an additional prevention choice as part of comprehensive prevention. Countries are now following to adapt and implement these recommendations within own epidemiological settings.
Successful long-term ART results in a gradual recovery of CD4 T-cell numbers and an improvement of immune responses.
U.S. Preventive Services Task Force. Screening for HIV. Available at http://www.uspreventiveservicestaskforce.org/uspstf/uspshivi.htm. Accessed: June 16, 2011.
Sharp PM, Hahn BH; Origins of HIV and the AIDS pandemic. Cold Spring Harb Perspect Med. 2011 Sep 1(1):a006841. doi: 10.1101/cshperspect.a006841.
Branson BM, Handsfield HH, Lampe MA, et al. Revised recommendations for HIV testing of adults, adolescents, and pregnant women in health-care settings. MMWR Recomm Rep. 2006 Sep 22. 55:1-17; quiz CE1-4.