What is done to prevent the spread of black plague?

Good sanitation. In general, plague is prevented by eliminating rodents and fleas, especially in the areas where plague is known to be endemic (like the western United States). Antibiotic prophylaxis (prevention) can be considered for people who are exposed to potentially-infected rodents or fleas.
Pasturella pestis. Is the infectious bug carried originally by rats within centers of abysmal hygiene in europe, prior to any understanding of epidemiology. The potential for future plague is almost non-existent in modern countries, but realize that squirrels, prairie dogs, and many other wild animals may harbor fleas and could infect individuals. We of course, now possess potent antibiotics.