Viruses cause a number of diseases in eukaryotes. In humans, smallpox, the common cold, chickenpox, influenza, shingles, herpes, polio, rabies, Ebola, hanta fever, and AIDS are examples of viral diseases.Even some types of cancer -- though definitely not all -- have been linked to viruses.n humans, smallpox, the common cold, chickenpox, influenza, shingles, herpes, polio, rabies, Ebola, hanta fever, and AIDS are examples of viral diseases. Even some types of cancer -- though definitely not all -- have been linked to viruses.
Map of the fortifications. Located in Canada, the Ramparts of Quebec City are the only remaining fortified city walls in North America north of Mexico. The British began refortifying the existing walls, after they took Quebec City from the French in the Battle of the Plains of Abraham in 1759.
A brick wall. A wall is a structure that defines an area, carries a load, or provides shelter or security. There are many kinds of walls: Defensive walls in fortification. Walls in buildings that form a fundamental part of the superstructure or separate interior sections, sometimes for fire safety. Retaining walls, which hold back dirt, stone, water,or noise sound. Walls that protect from oceans (seawalls or rivers levees) Permanent, solid fences.