CD-ROM: Sample Chapter

Index:

Synonyms

  • Herpetic infection
  • Genital cold sores
  • Human alphaherpes virus

Definition

Infection of the genito-anal area with Herpes simplex virus (HSV) type 1 or type 2, a DNA virus of the Herpesviridae family (image 2).

Classification

Incubation period

Three to nine days if symptoms occur. However, up to 90% of primary infections may be asymptomatic.

Clinical manifestations and symptoms

The primary lesion of an HSV infection is a group of multiple clear vesicles on erythematous skin or mucosa. After one to three days vesicles become pustular, and finally erode to become painful shallow erosions with a yellow floor and red edge. In primary genito-anal herpes infection there is also tender inguinal lymphadenopathy and sometimes malaise, myalgia and headache. There can be intense genital pain and dysuria. Crusting and healing occurs after one to three weeks. Recurrences occur in some patients, generally lasting only a few days, with less severe lesions.

Localisation

Anywhere on the penis, scrotum, vulva, vagina, cervix or perianal area.

Epidemiology

Common world-wide in both sexes. Primary infection with HSV type 1 usually occurs on the face in childhood, and confers partial immunity against later genital infection occurring in adolescence and young adulthood. Greater prevalence in lower socio-economic groups, and in people with multiple partners. Lesions on perianal skin or in the anal canal are more common in homosexual men. Genital lesions occur in heterosexual and homosexual people. The main risk factor is unprotected sex with an infected individual. Asymptomatic viral shedding promotes transmission to sex partners. Vaccines are being trialled.

Laboratory

Enzyme immunoassay (EIA) and immunofluorescence (IF) microscopy (Microtrak®) are rapid diagnostic methods. Cell culture is slower. IF and cell culture allow typing for HSV 1 and HSV 2. Serology is of more value for epidemiological surveys than for individual clinical diagnosis.

Histopathology

Ballooning degeneration of keratinocytes and intercellular oedema lead to deep intra-epidermal vesiculation. Characteristic multinucleated giant cells may appear in the epidermis, containing a dense basophilic intranuclear mass, followed by an intranuclear eosinophilic inclusion (Lipschütz or Cowdry Type A inclusion). Predominantly mononuclear infiltration, followed by influx of polymorphonuclear leucocytes. Localised necrosis and ulceration occur.

Pathogenesis

Direct inoculation of the virus through skin and mucous membranes results in local lesions and travel of the virus along the peripheral nerve fibres to the sacral dorsal root sensory ganglion. There the virus resides indefinitely. From time to time, virus particles travel distally to the submucosa and skin, sometimes resulting in new vesicles and erosions. In this way, one or more recurrences may occur. Recurrence rates for genito-anal herpes caused by HSV1 and HSV2 are 60-70% and 25% respectively.

Diagnosis

Characteristic group of vesicles or ulcerations is highly suggestive.

The Tzanck test (Wright, Giemsa, Diff-Quik® or Hemacolor® stain) (image 21) or Pap smear (Papanicolaou stain) (image 22) can be used to demonstrate cytologic changes in specimens from suspected mucocutaneous HSV lesions. The cytologic changes include ballooned and multinucleated giant epithelial cells, and Cowdry type A intranuclear inclusions. The Tzanck test is an inexpensive and rapid method for diagnosing patients with non-life-threatening illness. A negative Tzanck or Pap smear is not conclusive for the diagnosis of HSV in critical situations such as infections in pregnant women at term, or in new-borns.

Confirmation is by EIA or IF testing of a specimen taken from fresh vesicles; or by four-fold rise in IgG serum titer or by detection of IgM to Herpes simplex virus.

Differential diagnosis

  • Zoster
  • Fixed drug eruption
  • Primary syphilis
  • Lymphogranuloma venereum
  • Chancroid
  • Friction trauma
  • Candidiasis
  • Balanitis/vulvitis

Treatment

Topical application of antiviral agents is of limited value. Antiseptic solutions have a drying effect. Local anaesthetic (e.g. 2% lignocaine) gel and oral analgesics (e.g. 1 g of paracetamol four hourly) can be very soothing, together with warm saline sitz baths.

Acyclovir is the specific treatment of choice for primary episodes, 200 mg tablets five times daily for up to seven days. Intravenous acyclovir 500 mg eight-hourly is occasionally needed. Recurrences can be suppressed by one acyclovir tablet three times daily.

Newer agents include valaciclovir (the pro-drug of acyclovir) (3 x 1g/d, suppression 2 x 500mg/d) and famciclovir (the pro-drug of penciclovir) (3 x 250mg/d, suppression 2 x 125mg/d).

Follow-up

Patients with primary herpes should be reviewed at one to three day intervals. All patients should be tested for syphilis and other STDs. Patients on suppressive treatment for recurrences should be seen at one to three month intervals.

Complications

Severe dysuria with urinary retention may require hospitalisation. Meningoencephalitis is rare. The commonest complication is multiple recurrences over a period of months or years. HSV2 may also be a cofactor in causing squamous cell carcinoma of the cervix, along with HPV 16, 18, 31, 33 and tobacco smoking.

Prognosis

Most patients experience one episode only, i.e. without any recurrences. Emotional and physical stresses are likely to perpetuate recurrences.

Management of sex partners

Partners should be assessed for signs or past symptoms of genital or oral herpes, and tested for other sexually transmissible diseases. Antiviral treatment is only indicated if troublesome symptoms are present.

Acknowledgements

Images 6 - 7 - 8 - 9 - 15 - 16 - 17: courtesy of Dr. Margaret Sparrow and Dr Hilary Andrews, Sexual Health Service, Wellington Hospital, New Zealand.

Literature

Adler MW. ABC of sexually transmitted diseases. 3rd edition (1995) British Medical Journal Publishing Group, London.

Arvin AM, Prober CG. Herpes Simplex Viruses. In: Murray PR, Baron EJ et al. (eds.) Manual of Clinical Microbiology. Washington, DC, American Society for Microbiology (1995) 876.

Benenson AS (ed): Control of communicable diseases manual. 16th edition (1995) American Public Health Association, Washington DC.

Folkers E, Oranje AP et al. Tzanck smear in diagnosing genital herpes. Genitourin Med 64 (1988) 249.

Holmes KK, Mardh P.-A. et al. (eds): Sexually transmitted diseases. 2nd edition (1990) McGraw-Hill, New York.

Robertson DHH, McMillan A et al. Clinical practice in sexually transmissible diseases. 2nd edition (1989) Churchill Livingston, Edinburgh.

Thin RN, Barlow B et al. Int J STD & AIDS 6 (1995) 130.

van Praag MCG, van Rooij RWG et al. Diagnosis and treatment of pustular disorders in the neonate. Pediatr Dermatol 14 (1997) 131.

World Health Organization: Management of sexually transmitted diseases (1994) WHO/GPA/TEM/94/Geneva.

Self-assessment questions

  1. What are the classical clinical features of primary Herpes simplex virus infection?
  2. What is the definitive laboratory diagnostic test for HSV2?
  3. Describe the characteristic histopathological process of genito-anal herpes.
  4. What are the relative roles of topical and systemic antiviral treatment?
  5. Should partners of patients with primary genital herpes be tested for other sexually transmitted diseases?