Initial research seems to indicate that there's no correlation between owning cats and contracting toxomoplasmosis.
The incidence of brain cancer appears to increase when people are exposed to Toxoplasma gondii (earlier studies linked higher serum antibodies in the population to higher levels of brain cancer), so a study was performed in the UK to see if cat owners had a higher rate of brain cancer than non-cat owners.
In total, 626 454 women aged 64 years on average at baseline were included in the analyses, among whom, 114 614 (18%) owned at least one cat.
Incidence of brain cancer was not increased in women living with a cat (RR = 0.88, 95% CI = 0.62–1.24), when compared with women living with no pets. Similarly, no association was observed for all CNS tumours, or for specified glioma or meningioma (table 1). In conclusion, cat owners in a cohort of middle-aged UK women do not have an increased risk of brain cancer, when compared with non-cat owners. This, however, does not rule out the possibility that T. gondii infection from another source may be associated with brain cancer incidence.
It's theorized that a significant source of T. gondii infections may be from a source other than the cats themselves. Improperly cooked meat, unwashed vegetables and fruits, and handling contaminated soil (such as in the garden) are all known risk factors that may play a bigger role in transmitting T. gondii to humans.