As part of a special collection of articles on HIV, this week's issue contains a Feature by Linqi Zhang of Tsinghua University in Beijing and his colleagues on the status of HIV in southern China (see page 609). Their conclusions are alarming: HIV prevalence is no longer confined to high-risk groups such as those who inject themselves with drugs, but is now seeping into the general population. Some of the most rapid increases are among men in same-sex relationships. Moreover, the findings confirm what veteran outside-observers of China and those concerned with HIV globally have long suspected: patterns of infection in southern China are similar to those in other developing countries — especially those experiencing large-scale migration from rural areas to cities, which provides men and women with more opportunities for sex.

Giving outsiders access to sensitive public health information would have been unthinkable in China even a few years ago.

The good news, however, is that China is doing more to make its AIDS statistics available. Traditionally, China has controlled access to such information very tightly. After the first AIDS cases were reported in the 1980s, for example, it took the Chinese government more than a decade to acknowledge publicly that the epidemic even existed. But during the SARS epidemic of 2002–03, the government's secrecy drew the outrage of Chinese journalists and non-governmental organizations alike; the resulting outcry led to a change in official attitudes.

The work of Zhang and his colleagues illustrates just how radical this change has been. Although the study was led by scientists inside China, the group included a leading US-based researcher, David Ho of the Rockefeller University in New York. The international team had full access to data supplied by government authorities — the results of tests from 3.2 million blood samples. And the authorities apparently made no attempt to control or influence the authors' opinions.

Giving outsiders access to sensitive public health information would have been unthinkable in China even a few years ago — just as it is in many Western countries even now. But then, China is slowly becoming more comfortable with the idea that all of society will benefit by sharing data and knowledge with others. Some of this transparency can be traced back to 1972 and the landmark meeting between US President Richard Nixon and China's Chairman Mao Zedong. As noted by the historian Margaret MacMillan, author of the 2007 book Nixon and Mao: The Week that Changed the World, China had a very pragmatic reason for the rapprochement: it needed access to US technology. That opening was greatly expanded by Mao's successor, Deng Xiaoping. Deng accelerated scientific contacts with the rest of the world, sent hundreds of thousands of Chinese students to study in Western universities, and in 1987 hosted a landmark scientific conference in Beijing between China and the international community (see page 598).

Of course, opening up on information is not the same as successfully controlling the spread of infection. Much more needs to be done if the government is to meet its self-imposed target of limiting the total number of cases of HIV infection to 1.5 million by 2010. Nonetheless, transparency is an essential first step. There are the many nations — in North Africa and the Middle East, for example — where public discussion of HIV and its causes is still not as open as it could be.

China was once in a similar position — but it changed. There are many good reasons why others should follow suit.