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
Most of the time, you will become contagious about  24 to 72 hours after contracting the influenza virus and remain that way for up to five days after the onset of symptoms. But children or people with compromised immune systems can be contagious to those around them for up to two weeks.