My aso titer is 270 how many days it take to become normal how it can be prevented?

Anti-Streptolysin O: Not days. Maybe months. but it depends on what specific Group A Strep infection you have or had and for how long and also how your particular immune system functions.You "prevent" an elevated ASO titre by not getting infected or significantly colonized with Group A Strep(the kind that can cause a wicked sore throat or an acute kidney problem or rheumatic fever).It's just used as a gauge, not cure)