They were never angels, but when Lisa told her two teenage daughters she was sick with HIV, they really started acting out.

On the day she sat them down about a year ago, the girls, age 13 and 14, immediately exploded with questions.

“Who’s going to take care of us?” they demanded. “Where are we going to live? How are we going to eat?”

Then the girls began to rebel, the 33-year-old Bedford-Stuyvesant resident, who asked that a pseudonym be used, recalled. Her daughters were “cutting school, talking bad, arguing with people,” she said, adding, “The oldest, all she wanted to do was be in a fight or get in a fight. … The other one got kicked out of junior high school.”

As World AIDS Day is commemorated today, the United Nations and advocacy and research groups around the world plan to shine a light on the global female face of the devastating disease.

Isis Sapp-Grant is the director of a community organization that works with Bedford-Stuyvesant’s most at-risk girls, including Lisa’s daughters. For her, the impact of AIDS is keenly felt.

Almost every girl who goes to Ms. Sapp-Grant’s Youth Empowerment Mission, an organization working with girls at the highest risk or with a problem of gangs or delinquency, has a family member with the disease, she said, and about a quarter have a parent who is ill or died because of AIDS.

“We’re talking about a whole new population of girls,” Ms. Sapp-Grant said. “It’s something we didn’t see 10 to 15 years ago. This is something different: a high-risk young person with a parent with this illness.”

The parents, she said, tend to be in their late 20s and 30s, and they had children in their teens during the crack epidemic and the simultaneous emergence of AIDS. Additionally, many of the teenage girls who come to the program have HIV themselves.

With a tally of 4,938 people in Bedford-Stuyvesant and Crown Heights living with HIV, according to the most recent statistics from the New York City Department of Health and Mental Hygiene, the neighborhood has one of the highest infection rates in the city. African-American and Hispanic women account for less than 25 percent of the country’s female population, but they account for almost 80 percent of all female AIDS cases reported to date, the Centers for Disease Control has found.

Advocates say children whose parents are infected with HIV and AIDS often fall through the cracks of city services provided to treat the epidemic and are increasingly common.

Ten years ago, four women working at the city’s Department of Social Services founded the Family Center, an organization to assist primarily low-income children whose parents have life threatening illnesses such as AIDS or cancer. The founders observed a great need to prepare the children for death, mourning, and rebuilding their lives.

One of the founders, Jan Hudis, said Lisa’s daughters’ initial questions and their disruptive behavior in school are common responses of children with infected parents.

“There are three basic questions,” Ms. Hudis said. “‘Who will take care of me? Will this happen to me? And will it happen again?’ Families often need support in developing answers and responses specific to those questions.”

For Lisa, at least for now, there has been a happy ending. Her daughters’ behavior has improved, she said, thanks both to her reassurances that they will be taken care of if she dies, and to Youth Empowerment Mission.

“I have attempted to tell them I don’t want them living for me, I want them living for themselves,” she said. “There is so much out there.”