Don't cheap out on your windsheild washer fluid....
The guys over at Autoguide.com recently reported on an article regarding a study about contracting Legionnaires disease. According to the study you are 20% more likely to contract the sometimes fatal disease if you use water instead of premium windshield washer fluid. The water is a more likely agent to house the virus according to the study. Click the link for the full article.
It's very important, at least sometimes, to handle the steering wheel and dashboard with antiseptics, it's also important to ventilate the car, clean the air conditioner and make sure that there is no mildew in the cabin under the rugs.
Legionnaires disease can be cured and this disease is no more dangerous than the flu. Also, the chance of getting them is pretty small. You can read on this portal CanadianPharmacy.com more about which pills are used to treat this disease. I think you should take care of your health, but hypochondria is a more serious disease than Legionnaires disease.