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  1. How is HIV primarily transmitted?

  2. Which cells does the HIV virus primarily infect?

  3. What are the symptoms and signs of primary HIV infection?

  4. What is the preferred test for diagnosis of HIV, and how is AIDS defined?

  5. What is meant by the term “the window period”?

  6. How is HIV activity monitored?

  7. Below what CD4 count does the host begin to experience opportunistic infections?

  8. What are the indications for initiating antiretroviral therapy?

  9. What are the goals for therapy, and what are the factors that increase the risk of developing resistance?


Management of HIV is challenging and complex. The associated opportunistic infections are often difficult to diagnose and frequently life-threatening.


Having originated in Eastern Africa between 1910 and 1950, by transmission of a precursor virus from a chimpanzee, HIV infection has spread across the world. Sub-Saharan Africa remains the epicenter of the epidemic: More than 1 million new infections occur annually, 23 million Africans are living with HIV, and more than 10 million have already died. Uganda alone has lost close to 3 million people due to AIDS: a crashed jumbo jet’s worth of deaths daily, every day from 1985 to 2011, in a country with a population of 20 million. In the sub-Saharan countries, transmission occurs predominantly by heterosexual intercourse, with as many women as men being infected. On average, infected women are younger than infected men, but overall, the most productive age strata is where the infection predominates, contributing to the disastrous socioeconomic impact of the AIDS epidemic. There is, however, recent progress: Since their peak, the yearly number of new infections and of AIDS-related deaths have approximatively halved.

The problems of North America and Western Europe pale in comparison with those of Africa. Nonetheless, the number of HIV-infected people living in the United States has reached more than 1 million. Incidence figures are difficult to determine, because most newly acquired infections are not diagnosed. Judging from the number of first positive tests (which may be the result of an infection acquired years earlier), infection rates declined during the 1990s, reaching a plateau around 1998, and declined further from 2012 (13.1 new infections diagnosed per 100,000) to 2017 (11.8).

The influence of highly active antiretroviral therapy (HAART) on the HIV epidemic has been hotly debated. By lessening the fear of AIDS, HAART may indirectly encourage risky sex and increase transmission of HIV. However, by decreasing viremia, HAART also decreases transmission. This effect of HAART has become increasingly evident, particularly in cities, such as San Francisco, where the expansion of HAART was actively promoted.

The probability of acquiring an HIV infection varies depending on the type of exposure. Transfusion with a unit of HIV-infected blood is almost certain to infect the recipient. In the absence of treatment, the child of an HIV-positive mother has about a 30% chance of ...

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