When the premises of the American Civil War forced the textile mills of Mississippi to a virtual stop, and the Russian Empire started seeking new cotton suppliers for its huge domestic market, Ludwig Knoop had a brilliant idea.

The so-called hygiene hypothesis claims young children need to get in contact with a number of relatively benign pathogens to develop a robust immune system .

Are allergies and so-called autoimmune diseases, like type 1 diabetes, likely to be caused by a lack of exposure to relatively benign pathogens in early childhood? This theory is referred to as the hygiene hypothesis.