There is new evidence that adult HIV infection rates have decreased in certain countries and changes in behavior to prevent infection, such as increased use of condoms, delay of first sexual experience and fewer sexual partners, have played a key role in these declines.

The annual report by the Joint United Nations Program on HIV/AIDS (UNAIDS) and the World Health Organization WHO indicates, that overall trends in HIV transmission are still increasing, and that far greater HIV prevention efforts are needed to slow the epidemic.

Kenya, Zimbabwe and some countries in the Caribbean region all show declines in HIV prevalence over the past few years, with overall adult infection rates decreasing.

Several recent developments in the Caribbean give cause for guarded optimism, with some HIV declines evident among pregnant women, signs of increased condom use among sex workers, and expansion of voluntary HIV testing and counseling.

''We are encouraged by the gains that have been made in some countries and by the fact that sustained HIV prevention programs have played a key part in bringing down infections. But the reality is that the AIDS epidemic continues to outstrip global and national efforts to contain it,'' said UNAIDS Executive Director Dr Peter Piot.

The report recognizes that access to HIV treatment has improved markedly over the past two years. More than one million people in low-and middle- income countries are now living longer and better lives because they are on antiretroviral treatment.