Good news everybody!

Browsing through some of the more recent papers on toxoplasmosis I came across this gem from last year:
Toxoplasma gondii Infection in the Brain Inhibits Neuronal Degeneration and Learning and Memory Impairments in a Murine Model of Alzheimer's Disease

Immunosuppression is a characteristic feature of Toxoplasma gondii-infected murine hosts. The present study aimed to determine the effect of the immunosuppression induced by T. gondii infection on the pathogenesis and progression of Alzheimer's disease (AD) in Tg2576 AD mice. 
...
In addition, water maze and Y-maze test results revealed retarded cognitive capacities in uninfected mice as compared with infected mice. These findings demonstrate the favorable effects of the immunosuppression induced by T. gondii infection on the pathogenesis and progression of AD in Tg2576 mice.

So it's not all bad - at least if you're a mouse. A more digesitible summary of this research appeared in the Economist magazine: It's all in your head