For herpes, according to CDC guidelines, testing is only done if there are symptoms and there are several reasons for this distinction. First, research shows that diagnosing herpes in a person with no symptoms does not change that person's sexual behavior or prevent herpes from spreading. The CDC doesn't recommend testing for herpes for people without symptoms in most situations. This is due to the limits of a blood test for herpes and the possibility of obtaining an incorrect result.
The chances of getting the wrong test results are higher for people who have a low risk of infection. Many people diagnosed with herpes feel betrayed by the medical system when they learn that they've never been tested for herpes before and that their partner probably hasn't been tested for herpes either. If you didn't know before, herpes isn't usually included in a standard STD panel. That means that all those screening tests that you've done so diligently since you started having sex, and those that you may have asked your partner to do as well, probably didn't include herpes.
Currently, there are several FDA-approved blood transfusion-based blood tests that can give accurate results for detecting herpes. Like any other blood test, these tests cannot determine if the site of infection is oral or genital. However, since most cases of genital herpes are caused by HSV-2, a positive result for type 2 antibodies is likely to indicate genital herpes. To obtain the most accurate test result, it is recommended to wait 12 to 16 weeks from the last possible date of exposure before taking an accurate and specific blood test for each type of organism, so that the antibodies have enough time to reach detectable levels.
In fact, the CDC recommends including herpes testing when patients request a comprehensive STI exam, especially if they have had several partners. STDs are a public health problem, so testing for STDs must be accompanied by education, which we hope will help reduce stigma. When it comes to testing for STDs, the general consensus and recommendation is that people should not be tested for herpes unless they have symptoms.