Thanks for your question and concern. I can understand your concern about genital herpes and HSV infection. Herpes is a viral infection caused by Herpes Simplex Virus. There are mainly two types of herpes viruses. They are HSV type 1 and HSV type 2. Of these, HSV type 2 is responsible for genital herpes. Both of these infections cause ulcers, blisters and sores in genital and facial areas. Type one of herpes causes cold sores usually in oro facial parts. But they can co exist and can exist vice versa, through oral sex practices. So both of these can exist in both oral or facial areas of body. Type 2 HSV is commonly seen in genital areas. They cause ulcers, sores, blisters and fever blisters in those areas. A positive test result means you either have got infected or your result is false. That means you may not have infection but the test shows so. There are a number of herpes confirmation tests available and all are reliable in one or other form.
It is worth noting that you need not have an outbreak or symptoms of herpes to have virus in you. Herpes Simplex Virus can stay in human body for a lifetime without causing any significant visible outbreaks, for years. During this dormant period itself, it can get transmitted to others. This make diagnosis of herpes erroneous and difficult. Blood tests and serum tests are done to find infection. There are antibodies of herpes which make it easy to find presence of virus. But no method has been found to determine the age of infection and how long it has been since the first outbreak. In your case, your girlfriend or the woman or both are likely to have herpes. They are unknowingly transmitting it to others through sex. The worst part of the disease is that carrier need not be aware of the infection and transmit it to others. Moreover tests are difficult to confirm infection and it is advised to take more than one test to get it confirmed. This is because various tests have various methods of determining the infection and has different chances of false positive.
Long before tests had high rate of false positive and false negatives for genital herpes and other variants of Herpes Simplex Virus. Now tests have become more specific and false positives have become reduced. Moreover some tests are not able to distinguish between HSV type 1 infection and type 2 infection. This prevails now also but there is no importance on the variety of virus. This is because, medicines used to treat symptoms of both HSV 1 and HSV 2 are same. Only the area where it is applied changes. Now tests are available for both HSV type 1 and type 2. If you have done a herpes type 2 serology test, and got a positive result, you are more likely to have herpes. Mostly, you might have got the infection earlier and not now. In some rare cases when there are no outbreaks, there is a possibility of false positive. However efficacy of tests depends on the type of test conducted. Now, in your case, you have got a positive test result. It is important to make up your mind, not to spread the infection to anyone else. You can consult your doctor for more details and for medication. Mostly you can avoid severity of outbreaks using antiviral medications like Valtrex and Acyclovir. But it is recommended that you should use them by the prescription of a doctor. Hope my answer helps. Take care.