The researchers modelled the effect of removing sick animals on the disease's prevalence in a small population.

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The traffic accident survey was designed to establish whether the level of Bovine TB infection in dead badgers, collected from road accidents, reflected disease prevalence in the badger population in the area.

BBC: NEWS | UK | England | Devon | One in seven badgers has TB signs

Nationally, there is much debate over how best to educate the nation's rapidly growing and diverse population of youngsters with autism, the prevalence of which has increased tenfold over the past 25 years.

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"Only in recent years have we begun to realise the prevalence and severity of sleep deprivation in our population, " said Professor Gillin.

BBC: Brain 'battles sleep deprivation'

She said there are different ways to determine prevalence and that the CDC is considering a total population study of autism, but that it is not yet under way.

CNN: South Korean study may lead to higher autism estimates

Diabetes prevalence increases with age, so the aging baby boomer population is attributing to rising costs.

CNN: 5 million more people living with diabetes

That compares with a prevalence of 4 percent for the general U.S. population, according to a 2005 study in the Archives of General Psychiatry.

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In Europe, about half the adult population is currently overweight, and urban areas of many developing countries have a similar prevalence, according to the International Agency for Research on Cancer.

BBC: Breast cancer risk for large mums