Aids in Africa ravages millions of lives, those infected as well as those affected. Increased international mobilization, particularly the XIV International Conference on AIDS in Barcelona, is crucial, but one acutely vulnerable group continues to suffer in silence - adolescent girls at risk of infection by sexual violence and other abuses.

With prevalence rates in several heavily affected countries five times higher than for boys, protecting girls should be a prime objective. Decisive steps now at the national and international level could have real impact, with relatively minimal financial cost.

On a recent trip to Zambia, I interviewed scores of girls impacted by HIV/Aids, ranging from discrimination in access to education to attacks on street children to sexual violence and coercion. These human rights abuses put girls at direct risk of infection, and must be addressed as part of the solution to the broader pandemic.

Alarming numbers of girls are targets of sexual violence, frequently by HIV-positive men. Some men seek out younger and younger girls in the hope that they will be Aids-free; others look for young girls based on the myth that having sex with a virgin will cure them of the disease. The low social and legal status of women and girls makes it exceedingly difficult for them to negotiate safe sex and to take steps to protect themselves from STDs or HIV infection.

The perpetrators of these abuses are not only unscrupulous older men, referred to as "sugar daddies," who coerce girls into sexual relations with offers of gifts and money. The tragic reality is that many abusers are precisely the adults with responsibility for caring for these children, such as close relatives and teachers. They use their power and status to compel girls to comply, underscored by threats of violence or abandonment if they refuse.

One of the girls I interviewed was Carol (not her real name), 17 years old and in grade 9, with a direct gaze. After her parents died, she went to stay with her aunt, but she told me: "I stayed with her, but then my uncle started sexually abusing me. He was about 34. He threatened he'd kill me if I told anyone about it." She went on to describe her fear: "I want to go for a test to see if I'm OK or not. I feel if it can happen to me, it can also happen to other girls my age. People like that are so cruel - they should be locked behind bars."

In most cases, victimized girls remain silent in the face of a legal and social system that fails to act to protect the girls' rights. Indeed, the obstacles that a girl would have to overcome in Zambia to report a case of rape or defilement appear overwhelming: she would face a police department that is rarely child or gender sensitive, a medical establishment that often scolds her for being promiscuous, a court system lacking any facilities for youths, and a societal structure that teaches girls to be submissive to men. Even if she did report an abuse, chances that officials would act against the abuser are minimal. As a result, the perpetrators remain free to abuse, and to infect, again.

Tragically, the spread of HIV/Aids to girls is the result of more than just shortcomings in the justice system. In the worst affected areas of southern Africa, hundreds of thousands of children are Aids orphans, with girls bearing the brunt of the burden of caring for ailing parents and taking responsibility for their siblings.

These girls are usually the first to drop out of school, which further reduces their access to information and their economic and social ability to protect themselves against HIV infection. All too often, they end up on the streets and engage in high-risk sex work as their only economic alternative.

Cases abound of girls trapped in abusive situations with a high risk of contracting HIV/Aids and virtually no ability to protect their rights. One vivacious and articulate 16- year-old to whom I spoke, Patricia (not her real name), lost both her parents. After her mother died, her uncle sexually abused her. Because he has been sick, the counselors working with Patricia are encouraging her to get an HIV test. She described her situation and that of many other girls: "After my mother died, I went to my mother's mother. In 2001, she died, so I stopped school, because I had no more sponsor. Then we went to my auntie, my mom's younger sister... Most girls find that they start keeping up [sleeping with] with stepfathers or uncles. Most are raped. They have no say. If you bring them to the police, there will be no one to keep me. So they keep quiet..."

Another 16 year old, let's call her Martha, lost her mother and went to live with her grandmother, but was being sexually abused by a neighbor. Others in the community ultimately reported her case, and she was sent to an orphanage. The orphanage was concerned because she was always sick, and she tested positive for HIV.

These all-too-common stories highlight the complexity of risk and transmission related to HIV/Aids. And they pose a clear challenge to the global response to the pandemic.

To a large extent, the remedies required to protect millions of other girls in Africa are not outrageously expensive, nor do they require a massive overhaul of the justice system. In most African countries, the laws are on the books - they need to be enforced. The police need special training in gender violence and child abuse, as do medical professionals and educators. Abuses against girls must be investigated and prosecuted, and stiffer punishments meted out.

Preventive administration of a short course of anti-Aids drugs should be given to rape victims, as it is in many countries. Communities need to be empowered to recognize and act upon signs of abuse. Governments, schools and communities should increase programs to keep girls in school and in a safe environment.

Allowing girls to suffer in silence not only perpetuates serious human rights violations, it facilitates the transmission of HIV. International and national policymakers meeting in Barcelona should muster the political will and take the steps necessary to break this cycle of abuse and transmission.

*Janet Fleischman, is Human Rights Watch's Washington Director for Africa. She conducted this research during a period of leave for the organization's Aids and Human Rights Project and its Children's Rights Division.