Thursday, 31 July 2014

Varicella in an adult

Varicella occurs throughout the world but infection occurs at a younger age in temperate zones (less than 10 years) compared to the tropics (teenagers). In temperate regions more than 90% of adults are immune to varicella while in tropical countries only 60% of adults are immune to it. Transmission is via the respiratory route and less commonly by direct contact with the lesions. There is an initial viral replication in the nasopharynx and conjunctiva. A susceptible person may develop varicella following exposure to the lesions of herpes zoster. The severity of the disease is age-dependent, with adults having more severe disease and more complications. However, neonatal varicella can be severe. Varicella confers lasting immunity and second attacks are uncommon, especially in immunologically healthy people, but clinical reinfection with a mild varicella-like illness occasionally takes place.

The distinctive features of varicella are the centripetal distribution, the polymorphism in each affected site and the rapid progression of the individual lesion from vesicle to crust. Vesicles are common in the mouth, especially on the palate, and are occasionally seen on other mucous membranes, including the conjunctiva and genitalia. On the anal mucosa they may be followed by painful ulcers.

Aciclovir is indicated for varicella in adolescents and adults (13 and older) and for severe varicella at any age in the immunocompromised. However, both immunocompetent children and adults with varicella benefit from acyclovir therapy thus therapeutic decisions are made on a case-by-case basis. Therapy does not appear to alter the development of adequate immunity to reinfection. 

Centripetal distribution

Resolving rash. The virus is transmitted by droplet infection from the nasopharynx. A brief first viraemic stage, when the virus can disseminate to other organs, is followed by a second viraemia coinciding with the onset of the rash. Patients are infectious to others from about 5 days before to 5 to 6 days after the onset of the rash and most non-immune people will contract the infection if exposed to someone in the infectious stage of varicella. Vesicle fluid contains a large amount of virus. Completely dry scabs are not infectious.

A characteristic feature is the presence of lesions at different stages in each site. Papules very rapidly become vesicles that appear over around 4 days with centripetal distribution.  Vesicles dry rapidly to become crusts within around 4 days. Crusts soon separate leaving shallow pink depressions that normally heal without scarring within around 2 weeks. Hyper- or hypopigmentation may persist for weeks and scars can occur in some.

This page was last updated in January 2019. 

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Main Works of Reference List (The first eight are my top favourites)

  • British National Formulary
  • British National Formulary for Children
  • Guidelines (BAD - BASHH - BHIVA - Uroweb)
  • Oxford Handbook of Genitourinary Medicine, HIV, and Sexual Health
  • Oxford Handbook of Medical Dermatology
  • Rook's Textbook of Dermatology
  • Simple Skin Surgery
  • Weedon's Skin Pathology
  • A Concise Atlas of Dermatopathology (P Mckee)
  • Andrews' Diseases of the Skin
  • Andrology (Nieschlag E FRCP, Behre M and Nieschlag S)
  • Bailey and Love's Short Practice of Surgery
  • Davidson's Essentials of Medicine
  • Davidson's Principles and Practice of Medicine
  • Fitzpatrick's Colour Atlas and Synopsis of Clinical Dermatology (Klaus Wolff FRCP and Richard Allen Johnson)
  • Fitzpatrick’s Dermatology in General Medicine
  • Ganong's Review of Medical Physiology
  • Gray's Anatomy
  • Hamilton Bailey's Demonstrations of Physical Signs in Clinical Surgery
  • Hutchison's Clinical Methods
  • Lever's Histopathology of the Skin
  • Lever's Histopathology of the Skin (Atlas and Synopsis)
  • Macleod's Clinical Examination
  • Martindale: The Complete Drug Reference
  • Oxford Handbook of Clinical Examination and Practical Skills
  • Oxford Textbook of Medicine
  • Practical Dermatopathology (R Rapini)
  • Sexually Transmitted Diseases (Holmes K et al)
  • Statistics in Clinical Practice (D Coggon FRCP)
  • Stockley's Drug Interactions
  • Treatment of Skin Disease: Comprehensive Therapeutic Strategies
  • Yen & Jaffe's Reproductive Endocrinology