DAKAR (Thomson Reuters Foundation) - Psychologist Agnès George has worked with more than a thousand victims of sexual violence in war-torn Central African Republic, but the brutal gang rape of a ten-year-old girl and her mother stands out as the health professional's most harrowing case. A group of armed men stormed into the family's home and threatened to kill the girl's grandmother unless the child undressed for them, said the Médecins Sans Frontières (MSF) psychologist. "The child cried and refused. The three men killed her grandmother, raped the girl, and even raped her mother before leaving," said George, who works at the MSF clinic for victims of sexual violence in the capital Bangui's General Hospital. Central African Republic has been plagued by violence between mainly Muslim Seleka rebels and Christian anti-balaka militias since the rebels ousted former ruler Francois Bozize in early 2013. The conflict, which has forced one in five people to flee their homes, has left the displaced, single mothers and young girls particularly vulnerable to sexual violence, George said. MSF has a dozen services for victims across the country, which treat physical injuries, test for sexually transmitted diseases, and offer psychological support. They also provide the victims of sexual violence with medical certificates that can be used as vital evidence in court if they want to take legal action against their attackers. "It is one part of securing convictions, and is important in cases where children have lost their virginity," George said. More than 1,000 victims have been treated since the services started in July 2014 - one in five of whom were aged under 18. Yet less than one in six sought help within 72 hours of being raped, diminishing the quality of care they could receive. Many victims do not seek help immediately due to stigma surrounding sexual violence, information and services being disrupted by conflict and a lack of understanding, MSF said. "It's a long process as sometimes the victim feels guilty and ignored - so why would they look for help?" George said. The United Nations has been hit by a string of allegations of sexual abuse against women and children by its peacekeepers in Central African Republic over the last year. This may reflect a growing realization that sexual violence is pervasive throughout the country, according to George. While the French psychologist said it was important to address mental health in the country, she warned of the strain of the job on her and her colleagues. "You don't have to be a direct victim to develop symptoms of trauma and everything that involves - withdrawing into yourself, psychological problems and behavioral issues," George said. (Reporting By Kieran Guilbert, Editing by Ros Russell; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit news.trust.org)