"Given the right conditions pasteurised milk could be sold to Europe in the form of cheese, " Mrs Abeiderrahmane claims.

BBC: Milking a camel

But a recent study of pasteurised whole milk in shops by researchers at Marshfield Clinic Laboratories in Wisconsin found traces of the bug in 2.8% of the samples.

ECONOMIST: Another cow disease with a possible link to humans

Then a licensing officer told her that the code does not permit milk to be pasteurised a second time.

ECONOMIST: The authorities save Californians from a phantom menace

The White Moustache, however, was making yogurt from milk that was already pasteurised Ms Dashtaki bought her inputs from a fancy (and regulated) grocery store in half-gallon glass jugs.

ECONOMIST: The authorities save Californians from a phantom menace