In some states, patients who test positive for chlamydia or gonorrhea leave the clinic with not only a prescription for themselves, but also one for their sexual partner -- who was not seen by a doctor.

Thirty-eight states allow this public health measure known as expedited partner therapy, or EPT, which advocates say goes a long way in preventing sexually transmitted infections (STIs).

And states with the most permissible EPT laws may have the most success treating and preventing STIs, suggests a new University of Michigan study published online in the journal Sexually Transmitted Infections.

Researchers analyzed reported chlamydia cases from 2000 to 2013 and found that, on average, disease incidence in states with prohibitive EPT legislation grew significantly faster than in states where EPT was allowed. Read more via Science Daily