A recent story from Mexico may provide some clues. In 2006, a mysterious illness began to affect girls at a boarding school in Chalco, Mexico, near Mexico City. The school, which is run by Roman Catholic nuns, is one of 10 in Asia and Latin America operated by a charity called World Villages for Children in Asia.
There are also several marine mammals like Orca's (killer whales), harbor seals and sea lions that live in the Seattle area in the cold waters of Puget Sound and the Pacific Ocean and feed on the salmon and other fish. Douglas squirrels rely on the the evergreen trees that are native to the area.
Within its total area of 71,299 square miles, there is an average of 101.2 people for every square mile of Washington State territory. Seattle is the largest city in the state with a population of 684,451, with a density of 7,962 people per square mile. The Seattle-Tacoma-Bellevue metropolitan area has a population of 3.73 million, however, and encompasses nearby cities like Kent, Tacoma, Bellevue and Everett.