Varicella in an adult

Varicella occurs throughout the world but infection occurs at a younger age in temperate zones compared to the tropics. 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. 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. 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 adults and for severe varicella at any age in the immunocompromised. 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 2 days before to 5 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 August 2014. 

High-dose aciclovir hastening resolution of pityriasis rosea

The evidence that pityriasis rosea is a viral exanthem associated with reactivation of HHV-6 and/or HHV-7 is strong. Based on this concept, trials of antiviral drugs have been reported. The standard dose regimen of aciclovir is ineffective, but high-dose acyclovir (herpes zoster treatment dosage), used early after the onset of the eruption, may lead to a more rapid clearance of skin lesions. Here, the rash began to resolve soon after starting high-dose aciclovir (second photo taken at 2 weeks of starting aciclovir therapy). Without treatment, the disease duration usually varies between 4 and 10 weeks. Rarely, a partial or complete relapse of a fading pityriasis rosea may be seen. Second attacks occur in about 2% of cases. 

Interestingly, pityriasis rosea has been classified in Rook’s textbook of dermatology as a viral infection for many years before a viral cause was actually found. It has been stated in Fitzpatrick’s Dermatology in General Medicine textbook that this form of therapy should be considered in pityriasis rosea patients presenting early in their disease course who demonstrate associated flu-like symptoms and/or extensive rash. 

Before treatment 

Two weeks of starting treatment

  

The eruption is usually generalized, affecting chiefly the trunk and sparing sun-exposed surfaces but involvement of the face and scalp is quite common, especially in children. An inverse distribution, sparing covered areas, is not rare.

This page was last updated in February 2015.

Friday Meetings: Friday 31/10/2014

Friday 31/10/14 4 pm Cairo Time Google Plus Hangout

Discussion of cases in Dermato-Venereology  



Note that the specific tests are almost invariably positive in secondary and early latent syphilis (a DELAYED serological response may occur in secondary infection but this is rare, even in the presence of HIV). A false-negative non-treponemal test may occur in secondary or early latent syphilis due to the PROZONE phenomenon when testing undiluted serum. This may be more likely to occur in HIV-infected patients.


Free talks via Google Hangout on Fridays have been arranged. These Friday Meetings have been audiovisual online meetings where we have typed, talked and screen shared. The Handouts, when available, can be emailed on request unless they become out-of-date.

Similarly, Thursday Meetings have been developed to discuss Rook's Textbook of Dermatology on Google Hangout.