A woman who had had light periods and apparent contraception for four years after having a levonorgestrel intrauterine system (Mirena) fitted developed heavy, prolonged periods, and it was thought it was time for the device to be changed. The surprising thing was that it had worked at all, because gynaecologists eventually found the original device in the peritoneal cavity. Either it had migrated slowly over four years or—more interestingly—the local release of levonorgestrel in the ovarian fossa had brought about anovulatory cycles in the same way as the progesterone only pill (Journal of Family Planning and Reproduction 2005;31: 163-4).

The leprosy bacterium grows in humans, armadillos, and the footpads of mice—but not in test tubes. A genetics study of strains of Mycobacterium leprae from patients around the world now shows that a single bacterial clone that has spread but barely mutated over time is responsible for the world's entire leprosy infection. It now looks as if leprosy originated in East Africa, and Europeans and North Africans took it to West Africa. The slave trade took it from there to the Caribbean and South America (Science 2005;308: 1040-2).

It's not just type A people who are prone to heart disease. If you're a …