No abstract

Human immunodeficiency virus (HIV) type 2 infection is characterized by slower disease progression to acquired immunodeficiency syndrome than results from HIV-1 infection. To better understand the biological factors underlying the different natural histories of infection with these 2 retroviruses, we examined the relationship between HIV RNA and DNA levels and the rate of CD4(+) T cell decline among 472 HIV-1- and 114 HIV-2-infected individuals from Senegal. The annual rate of CD4(+) T cell decline in the HIV-2 cohort was approximately one-fourth that seen in the HIV-1 cohort. However, when the analysis was adjusted for baseline plasma HIV RNA level, the rates of CD4(+) T cell decline per year for the HIV-1 and HIV-2 cohorts were similar (a rate increase of approximately 4% per year for each increase in viral load of 1 log(10) copies/mL). Therefore, plasma HIV load is predictive of the rate of CD4(+) T cell decline over time, and the correlation between viral load and the rate of decline appears to be similar among all HIV-infected individuals, regardless of whether they harbor HIV-1 or HIV-2.

Mobility appears to be a key factor for HIV spread in rural areas of West Africa, because population movement enables the virus to disseminate and also because of the particularly risky behaviours of those who are mobile. More prevention efforts should be directed at migrants from rural areas who travel to cities with substantial levels of HIV infection.

It is not possible to know what the course of the HIV epidemic in Senegal would have taken in the absence of efforts at prevention. Certainly, several factors that pre-dated the occurrence of AIDS in Senegal laid the groundwork for a positive response. However, data from a number of sources do reveal the successfulness of efforts in prevention. From available data, Senegal can rightfully claim to have contained the spread of HIV by intervening early and comprehensively to increase knowledge and awareness of HIV/AIDS and to promote safe sexual behaviour.