The HIV epidemic
We begin this study session by describing the current extent of the HIV epidemic. In order to do this, we first need to remind you of several terms, which you will need to know again here as we describe the epidemiology of HIV/AIDS. Epidemiology is the statistical study of the occurrence, distribution, potential causes and control of diseases, disabilities or other health problems in human populations.
In relation to disease epidemiology, can you recall the difference between prevalence and incidence?
Prevalence refers to the total number of cases of a particular disease or health condition existing in a population at a certain point in time, or during a given period (e.g. a particular month or year). Incidence refers only to the numbers of new cases of a disease or condition that are identified in a given period.
In the context of HIV/AIDS, you will also come across the term people living with HIV (abbreviated to PLHIV) when describing epidemic statistics, and indeed when we talk about other aspects of this disease. PLHIV refers to everyone who is infected with the virus, whether or not they remain in good health or have developed any HIV-associated diseases, including AIDS.
As of 2012, approximately 35.3 million people have HIV worldwide with the number of new infections that year being about 2.3 million. In Africa, there were an estimated 22.9 million PLHIV in 2012. Thus, the prevalence of HIV infection in Africa was estimated to be 5% of the general population. Here in contrast to other regions women compose nearly 60% of cases.
An important factor for you to consider in terms of the impact of HIV/AIDS in your community is geographical distribution. Indeed, the average prevalence of HIV infection in urban areas in Africa is higher than in rural areas.
Another epidemiological factor that you should consider in order to help target prevention programmes is the fact that the highest HIV prevalence occurs in the 15–24 years age group.
