HIV Epidemiology

HIV, the Human Immunodeficiency Virus, is a disease that merits international concern, study, and research. The disease infects individuals of populations worldwide, causing these individuals to lose the functionality of their immune system and finally succumb to one or more opportunistic diseases. The disease is mainly spread via sexual intercourse or IV drug use (activities which result in body fluid exchange like blood and semen). HIV can also be passed from mother to child and can also be acquired during blood transfusions. The latter is now a rare form of transmission because extra precautions have been taken to screen blood for HIV.

There are two strains of HIV, HIV-1 and HIV-2. HIV-1 is the more prevalent form and also the one that causes the greater pathology. HIV-2 is a lesser found strain that is endemic to countries in West Africa. Presently, the majority of those infected with HIV are infected with the HIV-1 strain. When the infection progresses, the patient is diagnosed with acquired immunodeficiency syndrome (AIDS) . The CDC has associated this stage of infection with a patient's CD4 count of 200 or less per microliter.

It is interesting to note that when HIV first started appearing in the US, it was thought to be only isolated to the homosexual male population. However, after further studies in Africa, the ratio of male-to-female HIV infection was found to be 1:1. This affirmed that HIV can be transmitted by heterosexuals and infection is dependent on the past history of your partner and the contraceptives used during intercourse.

Below is a world map of estimated AIDS cases in adults up until the end of 1996. The regions of largest infection are sub-Saharan Africa, North America, and Southern & Southeastern Asia.

The figure below (Figure 1) represents the total number of AIDS cases in adults and children recorded from later 1970s until later 1995. The large number of reported cases from the USA reflects the intensity of research and the growing general awareness of HIV. However, Africa has the largest estimated number of AIDS cases.





While the WHO has predicted that new adult HIV infections per year will decrease in North America and Africa, Asia is headed for a large epidemic. Currently, southeast Asia has an extensive sex market which contributes to the rise in HIV infection. Current plans to try and curtail this rapid HIV expansion are to increase general awareness and to promote safe sex through the use of contraceptives.