• Multiple sclerosis
• sex ratio
• epidemiology

Australia has played an important role in MS research. The original migration of individuals from the British Isles meant that, unusually, it became possible to compare MS risks in transported cohorts to their stationary relatives. In Australian settlers, did the high native rate of MS risk in their countries of origin apply to the risk in a new continent with markedly different and graded environmental conditions? This became easy to answer, and there can be no doubt that MS risk dropped and that strictly genetic explanations were untenable. The rate of MS in Queensland is obviously lowered both to the naked epidemiological eye and to the practising neurologist there, most likely trained in Sydney or Melbourne and quite familiar with the disease. However, Tasmania has differed from the mainland in having higher MS risk, and it cannot be overlooked that its temperate climate more closely resembles that of the UK. The size of Tasmania has always been convenient for epidemiological studies, and in this issue Simpson et al (see page 180) extend previous studies.1

The results are clear enough for MS prevalence. The near …