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| Genital herpes |
1-Dec-2004 |
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A wide variation in genital herpes presentations is making this condition more difficult to diagnose, writes Dr Terri Foran.
CASE ONE
JAN, 40, has been troubled by recurrent thrush for five years. She has tried many preventive measures, including an anti-candidal diet advised by a naturopath friend. Some vaginal swabs taken over the years have grown candida, but most have shown only normal vaginal flora.
Jan’s main symptom is vulval irritation rather than increased vaginal discharge and, on examination, her vaginal discharge appeared physiological.
However, on closer inspection there were also two small vulval fissures near the vaginal entrance. A PCR swab from the base of these fissures gave us the correct diagnosis a week later — herpes simplex type 2.
CASE 2
REBECCA, 19, requested an appointment. Two days earlier she had developed vaginal irritation. A friend suggested she had probably picked up a yeast infection from her new sexual partner and had given her some leftover antifungal cream. But despite daily application of the cream Rebecca’s symptoms have worsened and now the pain is agonising, particularly on urination.
Physical examination reveals multiple shallow ulcers typical of genital herpes. These proved to be herpes simplex type 1 and not type 2, which is usually associated with genital herpes.
These two presentations represent the variability of the symptoms of genital herpes in Australia in 2004.
EPIDEMIOLGY
THERE are two kinds of herpes simplex virus — HSV1 and HSV2 — which are closely related to other human viruses that cause chicken pox and infectious mononucleosis.
Genital herpes was first described by a French physician in 1736, but it was not until more than 100 years later that it was recognised as a sexually transmitted infection. The incidence of genital herpes rises in the adolescent and early adult years and is higher in those with a larger number of sexual partners.
The most likely time to contract genital herpes is in the first few months of a relationship when sex is more frequent. Women seem more at risk of contracting the infection than men and this is probably because the thinner vulval skin is more likely to suffer micro-trauma during sexual activity. The virus relies on these small breaks in the skin to gain access to the sensory nerve endings that are its ultimate target.
Studies show that consistent condom use in long-term heterosexual relationships appear to reduce the chance of herpes transmission to the female partner when the male partner carries the virus.
However, condom use is less effective in preventing female-to-male transmission, perhaps because the most common site for viral shedding in women is the vulva and condoms offer little protection there.1
In most long-term relationships, the reality is an infected partner is likely to transmit the infection to the other partner, with an annual transmission rate of about 10%.
The incidence of infection with HSV2 varies from country to country, but about 20% of women attending an antenatal clinic in western Sydney demonstrated antibodies to the infection, although nowhere near this number would identify as carrying the infection.
When patients such as Rebecca present to their clinician with classic genital herpes the correct diagnosis is usually obvious. However, increasingly herpes infections are presenting with milder and more subtle symptoms, making the diagnosis more difficult. In some cases the symptoms are so mild and self-limiting that the person may not even seek medical advice until a sexual partner develops symptoms.
This wide spectrum of presentations is explained by the relationship between HSV1 (traditionally the virus that causes oral cold sores) and HSV2, which most associate with genital infection.
PRIMARY, INITIAL AND RECURRENT HERPES
A true primary attack of genital herpes occurs when a person has had no previous contact with either HSV1 or HSV2. A primary attack can be quite severe and may last up to 21 days if untreated.
In the past almost everyone was exposed to HSV1 in childhood. The antibodies to HSV1 provide partial protection in the event of subsequent genital exposure to HSV2. If a person previously exposed to HSV1 develops genital herpes, this is more correctly termed an ‘initial’ attack rather than a true primary attack. In such cases, the genital symptoms tend to be less severe and may be so mild as to pass unnoticed.
The term recurrent genital herpes is used to describe symptoms experienced after either primary or initial infection. Most recurrent attacks last less than a week and tend to become less severe and further apart with time.
Traditionally, those with herpes have been advised to avoid intercourse when lesions are present to prevent transmission to sexual partners.
However, as previously stated, most adults who test positive for antibodies to HSV2 have no idea that they carry the virus and it is likely that most infections are transmitted by those who are asymptomatic.
Even in those who do have recognisable clinical outbreaks, shedding of the herpes virus may occur between attacks. And since the severity of the infection depends mainly on the immune status of the person infected, the fact that an infected person experiences only mild and infrequent symptoms is no guarantee that their partners will also.
Although genital herpes is usually an uncomfortable but self-limiting infection, it can be associated with more severe complications, including urinary retention, sacral neuralgia, transverse myelitis, and encephalitis.
These more severe symptoms are more likely in the primary infection and in those who are immune-compromised.
CHANGING PATTERNS OF IMMUNITY
SINCE the 1980s several studies have shown a marked reduction in the number of people who have been exposed to HSV1 in childhood and therefore carry the antibodies that will mitigate subsequent HSV2 infection.
This may be a result of improved hygiene standards and smaller family groups, which lessen the chance of incidental exposure. Not only has this meant that we are seeing an increase in primary genital HSV2 infections, but a recent Melbourne study has shown that HSV1 is now the cause for one-third of genital herpes infections. This trend was even more marked in the younger age groups, with HSV1 being responsible for 70% of genital herpes in those under 20, possibly because of an increase in oral sex.2
It may be that the safe sex message has led to a perception that unprotected oral sex is less risky than penetrative sex in the transmission of sexually transmitted infection.
DIAGNOSIS
PCR testing, which detects minute amounts of viral DNA, has made the diagnosis of both HSV1 and HSV2 genital infection herpes much easier. It is particularly useful in less severe atypical lesions where the rate of viral shedding is much lower. Serological testing for both HSV1 and HSV2 is available, but has no place in the routine investigation of genital herpes. It may take several months after infection before levels of HSV antibodies are detectable, and a positive test has the potential to pathologise someone who has been previously asymptomatic.
In addition, testing gives no indication of the site of the infection.
Serological testing may be useful in certain situations, such as where the female partner of an affected male is unsure of her immune status and is considering pregnancy.
It is now understood that the major risk of transmission to the neonate is when a woman acquires a primary infection during the pregnancy, particularly in the third trimester.3
Neonatal herpes has high morbidity and mortality. In couples where the male partner is infected, but the woman has no immunity, many authorities recommend suppressive therapy for the male partner throughout the pregnancy and abstinence from vaginal sex later in the pregnancy.
TREATMENT
SUPPORTIVE therapy, such as rest, analgesia and the local application of antiseptics and anaesthetics, still plays an important role in the management of herpes, but the development of the antiviral drug acyclovir more than 20 years ago has revolutionised treatment. Acyclovir, and more recently valaciclovir and famciclovir, have an enviable track record for safety and low incidence of side effects.
When used early in the primary or initial episode of genital herpes, antivirals decrease the duration of the attack and the potential for severe complications.
Unfortunately, there is no suggestion that treatment at this stage affects the subsequent recurrence rate.
Antiviral medications have been shown to shorten the course of recurrent attacks by 12-24 hours.
Antiviral medications are also used as long-term suppressive therapy and data suggest they can reduce the rate of symptom recurrence by up to 70%. They may also reduce asymptomatic viral shedding and therefore the risk of sexual transmission.
Although it does not totally eliminate the risk, suppressive therapy may be particularly useful early in a relationship when the risk of transmission is highest.
Although there is a myth that stopping suppressive therapy will cause a “rebound” effect, it does not appear to increase the frequency of episodes so patients should be encouraged to take a break from therapy at convenient times to check on the progress of the underlying disease.
THE FUTURE
A vaccine against herpes simplex has proved elusive.
From a patient perspective, surveys indicate what is needed is a definitive diagnosis, discussion of the various treatment options and accurate information on the risk of transmission. Perhaps equally important is the ability to support the patient, particularly in the early course of the infection when there is no way of predicting the course of the disease.
REBECCA AND JAN
AFTER several more episodes of genital herpes, Rebecca started continuous suppressive therapy and has had no further attacks. However, she is extremely reluctant to take the recommended break from treatment because she fears this will increase her chances of passing the infection on to a sexual partner.
Jan continues to get occasional attacks of herpes, but is managing with only local therapy. After discussion, Jan’s female partner of six years decided to have serological testing and also tested positive for HSV1 and HSV2, although she has no history of either oral or genital infection.
1. Wald A, et al. Effect of condoms on reducing the transmission of herpes simplex type 2 from men to women. Journal of the American Medical Association 2001; 285:3100-06.
2. Tran T, et al. Changing epidemiology of genital herpes simplex infection in Melbourne, Australia, between 1980 and 2003. Sexually Transmitted Infections 2004; 80:277-79.
3. Brown ZA, et al. Neonatal herpes simplex virus in relation to assymptomatic maternal infection at the time of labour. New England Journal of Medicine 1991; 324:1247-52.
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