Sex, not injections, drives HIV epidemic in Zimbabwe

In the last year, several researchers have challenged the view that the HIV epidemic in Southern Africa is the result of sexual transmission, arguing that poor medical practice – and especially the re-use of syringes for injections - plays a bigger role than previously recognised. This claim is now strongly challenged in the journal AIDS by researchers working in Zimbabwe, based on a study of hepatitis C virus (HCV) prevalence among people living with HIV.

Historically, and around the world, there are several populations where HIV has definitely been transmitted through needle-sharing or by medical practices. For example, among injecting drug users and also among people with haemophilia (before screening was introduced for blood products). In all of these cases there has been a strong correlation between HIV and hepatitis C virus (HCV) with higher levels of HCV than of HIV, due to the fact that HCV is predominantly transmitted through the intravenous route. Its transmission tends to be more efficient than the transmission of HIV, making it a more reliable marker of transmission of blood-borne viruses through injection routes. In Africa, there appears to be no relation between HCV and HIV. Countries with the highest levels of HIV have low levels of HCV, and vice versa.

New evidence to support this observation appears in a letter to the journal AIDS from a Danish/Zimbabwean research team that is studying the relationship between HIV and schistosomiasis in a rural area of Mashonaland where 31% of adults they have tested are HIV-positive.

The researchers were able to test stored blood samples from 269 individuals, of whom 145 were HIV-negative and 124 were HIV-positive. Only one of the 269 tested positive for HCV, which shows that although the virus is present in this population, it is not widespread.

Seventeen of the whole population had received blood transfusions, among whom none were HCV-positive. Zimbabwe has had a longstanding infant immunisation programme, which currently involves a total of ten injections and achieves population coverage estimated in 1998 to be between 79% and 88% for the individual vaccines.

It is very hard to prove a negative and it is always possible that in particular places, including in Africa, poor medical practice does transmit HIV and other viruses. However, this report does add to what is already very strong evidence from a number of countries that a fast-growing and massive sexually-transmitted HIV epidemic can occur, among heterosexuals as well as among gay men, in the absence of significant needle-based transmission.