Rickets results from a severe deficiency of vitamin D, which helps the body absorb calcium. Rickets was historically considered to be a disease of poverty among children who toiled in factories during the Industrial Revolution, and some experts have hypothesised it afflicted literary characters like Tiny Tim in Charles Dickens' "A Christmas Carol."
Last month, Britain's Chief Medical Officer Dr. Sally Davies described the return of rickets as "appalling." She proposed the country give free vitamins to all children under five and asked the country's independent health watchdog to study if that would be worthwhile.
But in the last 15 years, the number of reported cases of rickets in hospitalised children has increased fourfold from 183 cases in 1995 to 762 cases in 2011. Experts said the actual number is probably even higher since there's no official surveillance system and it's unknown whether the disease has peaked.
"It's very surprising to see this," said Dr. Mitch Blair, an officer for health promotion at the Royal College of Paediatrics and Child Health.
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"This is not something we should be seeing because it's completely preventable." He said the condition was reversible once children start getting enough vitamin D, usually in tablets or injections.
Blair cited a number of reasons for the jump in rickets, including changing cultural habits like children spending more time playing indoors, the stringent use of sunscreen, and religious beliefs that mean skin is covered.
Children with dark skin are particularly susceptible, since they need a higher dose of sunshine than pale-skinned children. Unlike in other countries like Canada, the U and Australia, Britain does not fortify foods like milk or flour with vitamin D.