Transcript: HSV Diagnosis for New Nurse Practitioners

​Liz Rohr:
Well, hey there, it's Liz Rohr from Real World NP, and you're watching NP Practice Made Simple, the weekly videos to help save you time, frustration, and help you learn faster so you can take the best care of your patients.

So this week, I'm going to be talking about HSV types 1 and 2 and the overall approach to diagnosis, including the lab testing. So when it comes to HSV, it is incredibly common. So HSV-1 and HSV-2 statistics estimate about one in six patients have HSV-1 and about one in 20 people have HSV-2. It is a lifelong infection that hangs out inside of the trigeminal ganglia or the sacral ganglia, depending on the site of infection. And in fact, HSV-1 has been thought of as the oral infection when it can affect either oral or genital locations, same thing with HSV-2.

And the reason I give those statistics and this other statistic, I tried to find as many as I could. Interestingly it's based on population studies, of course, so the data varies. But for the most part, it sounds like about only 20 to 25 patients with HSV-1 have ever had clinical symptoms. So it is very possible that somebody has that lifelong infection, but they have never had symptoms and never will, which really ties into the testing and the patient counseling. Again, we'll circle back to that.

So when it comes to the infection, symptoms tend to occur about four days after exposure, anywhere from two to 12 days. And then the symptoms that patients will get really depends on a couple of things. It depends on the site of infection, whether it's oral or genital. It depends if it's a primary infection or a non-primary initial infection, or recurrent.

So primary infections refer to when patients have never been exposed to either HSV-1 or HSV-2, and those situations of being seronegative going to having an infection the first time, either strain, are more likely going to have more severe signs and symptoms. To be clear, though, not everybody has a severe presentation, even if it's a primary infection. So some patients will have subclinical symptoms, something very mild, or they might be completely asymptomatic and become a carrier. Like I said, with HSV-1, only 20 to 25%, based on the studies that we have, have shown that those patients who have HSV-1 in their systems have ever had clinical symptoms.

So non-primary infections refer to when somebody's been exposed, for example, to HSV-1, and then they become exposed to HSV-2, the symptoms tend to be a lot more mild because even though they're two different viruses, they have enough in common that that initial protection from HSV-1, HSV-2, vice-versa, will allow that kind of next iteration of infection to be a lot more mild, typically. So the most severe primary presentation when it comes to either oral or genital site, either HSV-1 or HSV-2. When it comes to the oral location, it actually, in adults, tends to present as a pharyngitis or as multiple oral lesions. And recurrent infections tend to be on the vermilion border, like the typical cold sore of what people think about, tends to be the recurrent infections and not the initial infection.

And so the more severe initial primary infections can have things like malaise, headache, fever, cervical lymphadenopathy, tonsillar exudate, about 40% of people, I understand, as well as some pharyngeal edema too. So it can be a pretty significant presentation that sounds a lot like strep or initial presentation of HIV. It sounds like quite a number of things. So it could potentially be the initial infection of either HSV-1 or HSV-2 just in the oral location.

And so again, primary infection of either HSV-1 or HSV-2 in the genital location can be really painful, inguinal lymphadenopathy, again, malaise, fatigue, headache, bilateral ulcerations. It can be vesicles, a grouping of vesicles on an erythematous base, but again, not everybody presents that way. That's kind of the classic textbook presentation, and I don't really have stats on that in terms of how many people present in that way, but just know that it can be shades of that presentation, and it doesn't always have to be the exact one.

And there's no real clear differentiation clinically speaking, looking at the vesicles or ulcerations that go with HSV-1 or HSV-2, and most of the vesicles will progress to ulcerations that are exquisitely painful, and the duration of the infection tends to be longer and more severe with those primary infections versus the recurrent ones or the non-primary initial ones. And the symptoms for oral lesions can be about eight days or so of that exquisite pain. And then for an initial genital infection can be to the range of about 19 days. It can last a long time, but the recurrent infections tend to be a lot shorter, five to 10 days or so.

So when it comes to recurrent infections, about 20 to 40% of patients, at least with HSV-1, can have recurrent symptoms or recurrent outbreaks. I don't have great data on HSV-2, I just couldn't find that, so I'm imagining it's very similar. Notably, HSV-1, when it's a genital infection, can cause recurrences in the first year but typically doesn't cause recurrences after that. So if you have a patient with recurrent genital vesicles, typically, that's going to be HSV-2.

And the rate of how often patients get recurrences and how severe they are can typically be correlated back to their initial presentation of how severe and how long of a duration their initial infections were, and that is a little bit predictive. It's really important, though, regardless, that we're letting patients know that it is likely. It's hard to say based on the statistics, but it's really important to counsel patients to expect a recurrence, except if it was in that case of HSV-1, generally speaking, might not recur after the first year. But, generally speaking, it's important to advise that there are recurrences.

Okay, so differential diagnosis and then approach to diagnosis. So differential diagnoses, the first two infectious ones are syphilis, that tends to occur as a painless indurated ulcer, though. It's very different from HSV, which is quite painful. And then, chancroid, that's how I've heard it pronounced. You might pronounce it differently. That can have a deep purulent ulcer with painful lymphadenopathy, so that sounds a little bit similar, so that's really important to keep in your differential. In terms of the non-infectious differential diagnoses, the top two ones are drug eruption as well as Behcet's. So those are very uncommon, a lot more common to have HSV, but it's really important to keep those top ones on your radar.

Okay, when it comes to diagnosis, so like I said, it doesn't always commonly present as that textbook group of vesicles on an erythematous base, so it's really important to do testing. We officially cannot do a clinical diagnosis when it comes to HSV, and so the gold standard is actually to obtain via swab, a PCR test, and unroofing the vesicles so we can get to the epithelial cells, which is not a pleasant procedure for the patient. It is painful for the provider to have to do that, but that is the most accurate gold standard one.

There's also the option of a viral culture that is kind of like second line to PCR. PCR can be a little bit expensive, so that's why sometimes we'll have a viral culture instead, a little bit more precise handling involved with that. And then, below that, are the Tzanck smear, T-Z-A-N-C-K was what used to be done, but PCR is really the gold standard now. So I'd recommend that you collaborate with your supervisor and your colleagues in your lab to see what the available options are and which specimens to obtain them with before you put a patient through that. Just to clarify which test you're talking about and how to appropriately send it out, so you don't have to do that to them again.

A huge question I get is about serology. So patients coming in asymptomatic would like to have serologic testing. So number one, it is not recommended for screening, and that is supported by USPSTF. The reason for that, and you may have talked about this already, but it's pretest probability. And so if you're testing people with a low pretest probability, a low likelihood of having HSV, it can lead to a lot more false positives. False positives and false negatives, so they're just really not that helpful. There are certain cases where we would consider it.

Kind of one specific thing I want to say. There's IgM, and there's IgG, and like I said, there's the initial primary infection, the non-primary initial infection, and recurrence. IgM is not helpful to distinguish between primary infection and recurrent. And when it comes to IgG, if you have an initial infection with somebody who has a positive IgG, it's not necessarily that helpful either. It's really important to get the PCR swab testing if we can. The most helpful situation is if you have somebody who has a partner with known HSV and the partner wants to know their status. You can send serology testing, and it's most helpful if it's completely negative.

Or if you have somebody who has a negative on file, and your PCR by swab is positive now, it is strongly supportive of an acute infection, but it's kind of getting into those little numbers. But typically speaking, it's really not recommended. And I really also harken back to what I said at the beginning of the video. If one in six people has HSV and only 20 to 25% of them have ever had symptoms, it's really not that helpful. And HSV is similar. I don't have the great stats on that, but it's a similar situation where one in 20 people have it, and not everybody is symptomatic, and it's not recommended for screening. So I just have a conversation with them of, "It's important to have safe sexual practices to prevent transmission because asymptomatic transmission between episodes, viral shedding, is possible." I don't have great data on that either, but it's definitely, unfortunately, a possibility.

So that's the overall approach to HSV diagnosis and testing. Please let me know what questions you have. If you haven't grabbed the Ultimate Resource Guide for the New NP, head over to realworldnp.com/guide. You'll get these videos sent straight to your inbox every week with notes from me, patient stories, and bonuses that I really just don't share anywhere else. Also, as always, if you're struggling with your lab interpretation, definitely check out the Lab Interpretation Crash Course at realworldnp.com/labs, the main labs in primary care. I'd love to help you out with that. Thank you so very much for watching. Hang in there, and I'll see you soon.