艾滋病的进化史(英文)

Natural history of HIV/AIDS Penny Lewthwaite

Ed Wilkins

AIDS was first recognized in 1981 and is caused by HIV-1. HIV-2 causes a similar illness, but is less aggressive and restricted mainly to West Africa. Continuous high-level HIV replication leads to virus-mediated and immune-mediated destruction of the key immune effector cell, the CD4 lymphocyte. T wo decades of study of the pandemic have provided a wealth of information about the natural history of HIV, leading to the development of highly active antiretroviral therapy (HAART), which has radically improved the prognosis.

HIV-1 and HIV-2 – HIV-1 can be divided into different groups (M, O and N) and genetic subtypes. Group M strains account for the HIV epidemic and have 11 subtypes (A–K). Each of these tends to be associated with a particular geographical area, with less strong associations with transmission categories and resistance patterns. Subtype B is most prevalent in the Americas, Japan, Australia, the Caribbean and Europe. HIV-2 infection differs from HIV-1 in that patients have lower viral loads, slower CD4 decline, lower rates of vertical transmission and slower progression to AIDS (12-fold lower). It is important to distinguish between HIV-1 and HIV-2, because HIV-2 is inherently resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs).

Epidemiology

HIV affects 40 million individuals worldwide, with 4.9 million new cases and 3.1 million deaths estimated by the WHO in 2004. Sub-Saharan Africa has the greatest burden of disease, with an estimated 26 million infected individuals. In Southern African countries, 25–40% of adults are infected; the prevalence is 5–15% in most other Sub-Saharan countries. South Africa now accounts for one-third of deaths worldwide. In the UK, 6600 new cases were reported to the Health Protection Agency in 2003; the prevalence was estimated at 53,000, using population estimates and anonymous linked testing.

Worldwide, the major route of transmission (> 75%) is hetero-sexual. About 5–10% of new HIV infections are in children and Penny Lewthwaite is Specialist Registrar in Infectious Diseases, Tropical

Medicine and General Internal Medicine at North Manchester General

Hospital, Manchester, UK. Conflict of interests: none declared.

Ed Wilkins is Consultant in and Clinical Director of Infectious Diseases

at North Manchester General Hospital, Manchester, UK. His research interests include the toxicity of HIV antiretroviral drugs, hepatitis

co-infection, and the investigation of treatment strategies. Conflict of interests: none declared.