It is almost IMPOSSIBLE to know who gave you herpes and most tests don't check for it, experts explains amid Usher scandal

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Usher was accused of knowingly transmitting herpes to two women and one man without disclosing he had the disease before they had sex. 

All three are suing the rapper with the help of celebrity lawyer Lisa Bloom. 

On Monday afternoon one of the victims, 21-year-old Quantasia Sharpton, spoke out about the nerve-wracking moment she learned about Usher's diagnosis - three years after sleeping with the singer. 

Sharpton said she has always loved Usher's 'artistry and music,' so her friends took her to a concert of his to celebrate her 19th birthday. 

She decided to sue Usher after documents were linked on July 19 showing that in 2012 Usher admitted to having herpes. Because he settled that case, it wasn't reported at the time.

The 21-year-old tested negative for the disease a year ago when she had her first son, but has sued the musician because she claims she would not have consented to intercourse with him had she known he had the virus.

But, even if Sharpton did have the disease, there would be almost no way to know that Usher had given it to her, a New York gynecologist Dr Alyssa Dweck tells Daily Mail Online. 

Here, she explains the nuances of the virus, how it is more common than we think, and it is possible to become infected from someone who unknowingly had a dormant infection... 

Usher has been accused of knowingly transmitting herpes to two women and one man, including 21-year-old Quantasia Sharpton (right) without disclosing that he had the disease before they had sex. But, according to a New York gynecologist, if they all do have the disease, there is almost no way of knowing it was Usher who gave it to them

If someone with the condition tests positive and has had multiple sexual partners, there is nearly no way to know who gave it to them because:

• It is hard to test for, and testing often reveals inaccurate results 
• Herpes is caused by two different viruses
• The condition can lie dormant in someone's body and never present any symptoms
• It's hard to prevent even with condoms

WHAT IS HERPES AND HOW IS IT CAUSED? 

There are eight strands of herpes viruses that can affect human beings, and only two of them cause the sores most commonly associated with the disease. 

Herpes simplex virus type one (HSV-1) and type two (HSV-2) both cause sores either in the mouth or on the genitals. 

But, the other six strands cause a series of other diseases including mononucleosis (mono, the kissing disease), chicken pox or shingles, roseola, a viral disease causing high fever and skin rash in children, and Kaposi's Sarcoma, a tumor most commonly found in people with AIDS. 

HSV-2 is responsible for most cases of genital herpes, while HSV-1 is typically responsible for oral infection, or cold sores, though it can also cause genital infections.  

Herpes is a chronic condition that cannot be cured, but symptoms can be controlled using antiviral medicines.  

According to 2010 data from the National Center of Biotechnology Information, 53.9 percent of Americans have type one, and 15.7 percent have type two.

However, the actual number of people infected is probably much higher, in part because data is old, and in part because the numbers only take into consideration diagnosed cases.

'Herpes is a very common infection,' Dr Dweck explained. 'And I think that people can take comfort in the fact that it's not as rare as people might think. It shouldn't be so stigmatized.'

On July 19, documents were leaked online, showing that in 2012, Usher admitted in court documents to having herpes. Because he settled that case, it was never reported at the time

WHY IS TESTING FOR THE CONDITION SO CONFUSING?

Testing for herpes is complicated and can gives inaccurate results, particularly because there are so many strains of the virus.

The US Preventative Services Task Force says people should only get tested if they are experiencing signs or symptoms. Testing is then done either by obtaining a swab with a viral culture from the site of infection, or via a blood test which detects the virus. 

But the methods aren't foolproof - the blood test has a very high false positive rate, and if someone tests positive for HSV-1 there's no way to tell if it is an oral or genital infection. 

'Testing isn't difficult itself, but it is difficult to interpret results. A patient can either be tested by taking a culture of the genital, oral, or anal lesion if it is active, or with a full blood test,' Dr Dweck explained. 

'Blood testing can be great because it can tell if it is an active, recent, or old infection, and can tell what type of herpes strain it is. However, it can't tell if it is genital or oral herpes, and the results can be otherwise difficult to interpret.' 

And because testing for herpes is so convoluted, there is no reason to assume someone is being irresponsible or unhealthy for not knowing they have the disease. 

WHY DO SO MANY PEOPLE NOT KNOW THEY HAVE HERPES?

Most people who have the disease don't know they have it because it lies dormant in their bodies.

In fact, a number of people  who have herpes never have an outbreak or any other noticeable signs or symptoms. 

According to the Centers for Disease Control and Prevention, roughly 87.4 percent of people between the ages of 14 and 19 years old who have HSV-2 don't know they have it.  

Even though these people have no symptoms, they can still infect someone. 

'If someone knows they have it, I feel that they are obligated to disclose that to their sexual partner,' Dr Dweck said. 

'But people might not know they have it because they might have never had a symptom or not realized a previous symptom.'  

WHY IS IT SO HARD TO AVOID INFECTION?  

And finally, there is no way to completely avoid infection. 

If someone has genital herpes, they can infect another person through sex during an outbreak. So things like condoms and taking daily antiviral medicine are all things that can reduce the risk of transmission.

But it's still not zero. 

'Other than abstinence, there is no rule that says when someone is able to spread the disease,' Dr Dweck said. 

'Even using condoms, they don't completely cover the genitals so it could still be transmitted.'  

And cold sores, which are much more common and caused by HSV-1 can be passed from mouth to mouth, or from mouth to genitals. Especially because in that case the virus can exits in saliva even if there aren't sores present. 

Currently, about half of all new genital herpes cases in women are caused by HSV-1. 

'If I had one message I would try to impress, it would be that herpes is common and it is chronic but it is manageable,' Dr Dweck, author of The Complete A To Z For Your V, explained.

'Herpes should really be destigmatized so people are more willing to disclose the infection to their partners and they can then deal with it intelligently.'