Varicella zoster virus: primary (varicella or chicken-pox) and secondary (herpes zoster or shingles) infections

Clinical presentation

The cutaneous presentation of primary and secondary VZV infection in patients with HIV commonly follows a typical course with crops of pruritic vesicles that become generalised in primary varicella and remain unidermatomal in HZ. In the setting of more advanced HIV infection, varicella is often more florid with a pronounced systemic prodrome (malaise, headache, fever and myalgia), has a prolonged course, and has a greater incidence of complications such as encephalitis, pneumonitis and hepatitis. Although mortality from varicella infection is somewhat higher in adults with HIV infection, children with HIV infection have a significant mortality rate from primary varicella infection and may also develop severe complications.[1]

HZ generally presents as a vesicular eruption involving one or more dermatomes. Most patients have prodromal pain in the affected dermatome before vesicular eruption.[2] This pain may be initially confused with other aetiologies.[3]

The classical rash of HZ is grouped vesicles or bullae, evolving into pustular and haemorrhagic lesions within a few days. Subsequently, crusting occurs and the resultant scarring may produce hypo or hyperpigmentation. The ulceration is often deeper and more prolonged, and scarring more severe. The diagnosis of HZ in the distribution of the ophthalmic division of the trigeminal nerve is important, as it can cause uveitis and keratitis. Ophthalmological review is indicated to minimise ocular complications.4 Disseminated cutaneous zoster has been defined as more than 20 vesicles outside the area of the primary and adjacent dermatomes, and is rare.[4]

Atypical, disseminated and chronic HZ infections usually occur in the setting of advanced HIV disease or IRIS. Chronic herpes zoster can present as indolent and chronic haemorrhagic, echthymatous or verrucous lesions.

The risk of HZ varies with the CD4 cell count. Increased rates of HZ occur in patients with a CD4 cell count of 50 to 200 cells/μL.[5],[6] Children with HIV infection who develop chickenpox have a higher incidence of developing HZ and are more likely to have recurrent HZ. A lower CD4 cell count increases this risk.7 VZV vaccination is important to consider in those with HIV infection.

Despite the established use of ART, the incidence of HZ has not decreased and patients remain at higher risk of HZ compared with the general population,[7][8] particularly with CD4 cell counts of 50 to 200 cells/μL.[9] IRIS-related HZ presentations are generally uncomplicated and can be managed with oral antivirals such as acyclovir, valaciclovir or famciclovir.[10] Isolated cases of transverse myelitis, keratitis, iritis and acute retinal necrosis in the setting of IRIS have been reported.[11] It is thought that the use of ART may be protective against complicated zoster.[12]