There may be something to the "crazy cat lady" stereotype
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.
10 Deadly Diseases That Hopped Across Species | LiveScience (30 April 2009)
http://www.livescience.com/health/090429-Deadly-Diseases-1.html
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.
10 Deadly Diseases That Hopped Across Species | LiveScience (30 April 2009)
http://www.livescience.com/health/090429-Deadly-Diseases-1.html