38 HIV in Otolaryngology
This is an important subject, as about 80% of patients who are human immunodeficiency virus (HIV) positive will develop ear, nose and throat (ENT) manifestations. A patient with newly diagnosed HIV infection needs to be adequately counselled and staged and then managed according to the stage. Combination anti-retroviral therapy (ART) is offered to all individuals regardless of CD4+ count.
38.1 Aetiology
Acquired immunodeficiency syndrome (AIDS) is caused by two of four retroviruses that cause disease in humans, namely HIV-1 and HIV-2. The other two are human T-lymphotropic virus types I and II (HTLV-I and HTLV-II) and transmitted in the same way as HIV and associated with several types of lymphoma and leukaemia.
AIDS is defined as the development of a complication of immunosuppression, such as malignancy or opportunistic infection, in a HIV-positive individual or immunosuppression such that the CD4+ T-cell count is less than 200 cm3. Immunisation and prophylaxis should be discussed and initiated but the detail of this is beyond the scope of this chapter.
38.2 Pathology
HIV-1 is prevalent worldwide, while the less virulent HIV-2 is found mainly in West Africa. HIV infects cells bearing the CD4+ antigen, which acts as a virus receptor. Such cells are monocytes, macrophages and T-helper cells. In HIV-1, the glycoprotein, gp120, binds to CD4+ and allows the virus to enter the cell. Viral replication may occur in cells in which HIV-1 DNA has been integrated (productive infection), although in some cells containing integrated HIV-1 DNA, the virus does not replicate except when the cell is activated by antigenic stimulation (latent infection), for example, Epstein–Barr virus or cytomegalovirus infection. Ultimately, a functional impairment and depletion of T-helper cells occurs. The ultimate consequence is a compromise of the host immune system. Immunosuppression places the victim at risk of developing opportunistic infections and unusual malignancies, particularly B-cell lymphoma and Kaposi’s sarcoma.
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