Dakar - The radio announcement is chilling and blunt: "If I die, I want the deaths to stop with me."Dr Desmond Williams continues: "I want to give my family the permission to request a safe and dignified, medical burial for me."The announcement is part of a campaign to urge Sierra Leoneans to abandon traditional burial practices that are fuelling the spread of Ebola in the West African country.Ebola has killed more than 2 000 people in Sierra Leone and unsafe burials may be responsible for up to 70% of new infections, say experts.Officials are resorting to increasingly desperate measures to clamp down on traditional burials in Sierra Leone, where Ebola is now spreading fastest. The head of the Ebola response has even threatened to jail people who prepare the corpses of their loved ones.Williams, a Sierra Leonean-American doctor who works for the US Centres for Disease Control and Prevention, took to the airwaves last month as part of efforts to encourage people to avoid dangerous burial practices. Now similar pledges have been made by prominent Sierra Leoneans, including the communications director for the health ministry, pop stars and radio DJ's.But old ways are hard to break. Many believe a traditional burial is necessary to make sure the dead don't return to haunt the living. Funerals are important social occasions in the three most-affected countries, Sierra Leone, Liberia and Guinea. People often travel great distances to attend and bodies are typically washed and dressed by relatives or friends.Unfortunately, these practices are the perfect breeding ground for Ebola: The bodies of Ebola victims can be up to 10 times more infectious than those of people living with the disease, according to the International Federation of the Red Cross.A well-attended funeral where many people touch the body provides the opportunity for the disease to disperse into a crowd and then be carried long distances back to their homes, where it can seed new clusters, according to Rebecca Bunnell, a behavioural epidemiologist with the CDC.People have been washing their hands more and avoiding crowded places, but changing burial traditions has proven particularly hard.Burial teams arriving at homes sometimes find the Ebola victims already washed or dressed. Now officials are warning that those who persist in traditional burial practices will be jailed once it's clear they have not caught the disease."Burials and funerals are deeply, deeply ingrained in Sierra Leone," said Austin Demby, a Sierra Leonean-American epidemiologist who has also taken the burial pledge. He is the director of a US government Aids programme, but has been helping with Ebola containment. "People put a lot of premium on this."It's hard to pin down just how many dangerous burials are taking place because they are secret, but even the most conservative estimates suggest that burials are responsible for at least one quarter of all infections in the region.In the early days of the Ebola epidemic, some families held their own burials because teams were slow to arrive or carried off bodies without telling relatives where they would be buried, said Bunnell of the CDC. But as more teams have been put in the field and relatives have increasingly been able to watch funerals, compliance appears to be increasing.The burial pledge is one more way to release families from the obligation of carrying out a traditional funeral. Some experts have also urged families to apologise to the corpse before handing it over for a safe burial, said Dr Nuhu Maksha, a health specialist with the UN Children's Fund in Sierra Leone.But the biggest motivator for change is the devastating toll on those who have prepared the dead, said Maksha: "People have to die before the others believe."