I was stalking a website that had facts about diseases that hop species.. meaning it can go from human to animal etc. This was interesting:
The bizarre parasite Toxoplasma gondii infects the brains of more than half the human population, including about 50 million Americans. It is thought increase the risk of neuroticism and may contribute to schizophrenia.
However, its primary host is house cats, in which the microbe reproduces sexually. Cats left to roam are more prone to picking it up. You can get it from cat feces. The bug is also found in many other mammals, too (where it reproduces asexually).
Initially, symptoms in humans are typically flu-like. But this bug never goes away. Some scientists think it has altered human behavior enough to shape entire cultures. Countries with high prevalence of T. gondii infection also have higher average neuroticism scores, one study found.
and also… for those of you who keep saying there is no way in hell the swine flu can turn out extremely bad, read this piece of history-
Flu history is frightening: The 1918 influenza pandemic swept the world within months, killing an estimated 50 million people — more than any other illness in recorded history for the short time frame involved.
One-fifth of the world’s population was infected, and it struck more than 25 percent of U.S. residents. Unlike some flu strains that mainly kill the elderly, children, and those with compromised immune systems, the 1918 strain hit young adults hard. In one year, the average life expectancy in the United States dropped by 12 years.