In the realm of potential threats to China's stability, an organization that advocates on behalf of people infected with hepatitis B would seem to be low risk. But on Wednesday, the group's director, Lu Jun, found himself squaring off against four security officials who were trying to cart away stacks of literature they claimed had been printed without official permission. In the end, Lu scored a partial victory. After eight hours looking through drawers and photographing volunteers, the inspectors walked off with 90 pamphlets, but Lu prevented them from delving into the group's computer files. 'I fear this is not the end of it,' he said Thursday. The raid on Lu's organization, the Yi Ren Ping Center, comes at a precarious time for China's nongovernmental organizations, many of which operate in a kind of legal gray zone. Two weeks ago, officials used a bureaucratic infraction to shut down the country's pre-eminent legal rights center, Gongmeng, or Open Constitution Initiative. The closing followed the disbarment of 53 lawyers known for taking on civil rights and corruption cases. Just before dawn on Wednesday, the founder of Gongmeng, Xu Zhiyong, was taken into police custody and has not been heard from since. 'The pattern of harassment, surveillance and detentions we're seeing suggests the government isn't satisfied with the extremely restrictive policies it already places' on nongovernmental organizations, said Phelim Kine, an Asia researcher for Human Rights Watch. Although it is unclear exactly why the government is tightening its grip on such organizations, legal experts and rights activists generally agree that it may be related to the celebrations, three months from now, that will mark the 60th anniversary of China's Communist revolution. A similar clampdown took place in the months before the 2008 Summer Olympics, when security officials in Beijing stepped up the harassment of dissidents and encouraged thousands of migrant workers to return to the countryside. 'It's basically a foolish attempt to make the year as peaceful and uneventful as possible,' said Jiang Tianyong, a lawyer who was among those recently blocked from renewing their licenses. Another explanation, Jiang and others say, is that some powerful segments of China's leadership feel threatened by the rise of independent entities working to advance causes like labor rights or clean water, or in the case of the Yi Ren Ping Center, protection for people with hepatitis B. There is widespread trepidation over hepatitis B in China, a fear that has been inflamed by an explosion in advertising for medical testing services and sham cures. Even though it is preventable through a vaccine -- and most of those infected will never become ill -- state-owned companies, medical schools and food processing plants have come to believe that it is common sense policy to bar the infected. According to Chinese law, carriers of hepatitis B cannot work as teachers, elevator operators, barbers or supermarket cashiers. In a recent survey of 113 colleges and universities, conducted by the Yi Ren Ping Center, 94 acknowledged that infected applicants would be summarily rejected. Many of the 120 million carriers in China contracted the virus in the 1970s and 1980s, when a single contaminated syringe was sometimes used to inoculate hundreds of students against diseases. The second biggest group of carriers, about 40 percent of the total, according to the government, contracted the virus from their mothers during childbirth. The online bulletin board maintained by Lu's group is a heart-rending clearinghouse for stories of people fired from jobs, or students denied college educations, because mandatory blood tests revealed their status. There are also scores of tales about the ashamed and the distraught who took their own lives. 'People are so afraid of this virus, they don't act responsibly,' said Wang Li, an engineer who just graduated from a prestigious Beijing university and saw two job offers evaporate this year when obligatory blood tests revealed his status. 'The only thing they told me was, 'You are not suitable for work.'' Founded in 2006 by Lu, who is also infected, Yi Ren Ping Center provides up-to-date medical information and tries to arrange legal help for those wrongly dismissed from jobs. It also encourages its 300,000 members to agitate for antidiscrimination laws. Last summer the center was forced to move its Web site to an overseas server after it mysteriously vanished from the Internet. Although his organization does not seek to challenge the government's authority, Lu recognizes its mission can stir discomfort among the powerful and mighty. 'After all, it is these people who are maintaining the status quo of discrimination,' he said, sitting in his office on Thursday. 'And of course, according to the government, there is no such thing as discrimination in China. There are only misunderstandings.' 