Can you be denied health insurance if you are diagnosed with herpes?

If you're in Washington state, if you're declined by the insurance company, you can enroll in the State's insurance pool plan. Depending on what state you live in.

In the state of Georgia, yes. If you live in Georgia and apply for individual health insurance, you can be denied if you or a member of your family has herpes and treats it with an expensive prescription. Even if the person was previously covered by the company under a group health plan.

Same situation in Minnesota also.

Given that the vast majority of the adult population has herpes, either orally or genitally, it would appear that the key is diagnosis. Some 80+% of adults have oral herpes and 25% has genital herpes. This is a complex issue, really, since most infected people don't know they have it, but are contagious at times.

Under the provisions of the Patient Protection and Affordable Care Act (aka "ObamaCare"), this would be considered a pre-existing condition, and could not be used as a basis to deny you coverage. This particular provision went into effect in 2014, and is applicable to ALL health insurance plans offered.