Africa and the Atlantic Slave Trade. Before the 16th century, Europeans were not deeply involved in slave trading on the West African coast. However, there was some movement of African labour to Madeira and the Canary Islands by the early Portuguese explorers from 1470 onwards.
urticaria is not contagious you cannot pass it on to another person acute urticaria or acute hives when symptoms last less than 6 weeks it is called acute urticaria this is by far the most common type 25 % of people with acute urticaria also have angioedema swelling in the deeper layers of skin
Based on previous studies, their best guess is that a person becomes contagious about two to three days before developing the usual symptoms of a cold. Second, this contagious period can last until the person no longer shows any symptoms. So in theory, a person is contagious for about two weeks.