Sir,

Herpes zoster caused by the reactivation of a latent varicella zoster virus infection (VZV) is a disease that may rarely develop in childhood, which remains quiescent in the dorsal sensory lymph nodes after chickenpox. Herpes zoster in children is rare, particularly in those immunocompetent, which may be responsible for post-herpetic pain requiring adequate and early treatment. Herein, we report a new such case.

This was a nine-year-old Moroccan girl with no noticeable disease history, more specifically: no notion of neonatal or maternal chickenpox during pregnancy and neither peri-natal nor a similar episode. She was vaccinated against chickenpox and was admitted for a dermatological consultation for a rash, which was described as a burning sensation in a single dermatomal distribution, present for three days, which was consistent with herpes zoster.

A physical examination showed that the child was afebrile with multiple vesicles grouped in a bouquet, resting on erythematous skin, affecting the left upper back with extension on the anterior chest (Figs. 1a and 1b). The diagnosis of herpes zoster was clinical, and the patient was discharged home with a prescription for acyclovir, analgesic, a spray to dry vesicles and a soothing cream. The evolution was marked by clinical improvement with the regression of pain. A minimal immune test was performed, including a complete biological blood count, blood sugar, and HIV serology, all of which were normal, with the HIV serology being negative. The current follow-up is six months without any recurrence or postherpetic pain.

Figure 1: (a) Vesicular rash affecting the left upper back region distributed in a single dermatome consistent with herpes zoster. (b) Extension on the anterior chest following a single dermatomal distribution.

Herpes zoster is caused by the reactivation of latent VZV in the dorsal root ganglia. Herpes zoster occurs most frequently in elders and presents with unilateral dermatomal vesicular rashes [1]. Although herpes zoster incidence has significantly decreased since the introduction of the live-attenuated varicella vaccination to prevent primary infection, varicella still affects children and is self-limited. In the case of vaccinated children, although they do not present varicella infection, both vaccine-type and wild-type viruses may remain dormant in the sensory ganglia, and as such its reactivation may be induced during times of stress, such as by trauma or malignancy.

With the increase in the number of shots from 1995, there has been a decreased incidence of HZ from 2003 to 2014, 74 per 100,000 person years for unvaccinated children and 38 per 100,000 person years for vaccinated children [2].

The reactivation typically presents initially with a prodrome of pain and paresthesia, followed by a macular rash. After approx. 24 hours, a painful vesicular rash erupts, confined to one dermatome, and eventually ruptures, crusts, and then resolves. Itching, pain, and paresthesia persist throughout the disease course and may be described as having a burning, sharp, and lancinating sensation. Hyperesthesia and hyperalgesia may also be associated with this condition. The pain is due to acute neuritis and is related to viral replication, inflammation, and cytokine production leading to neuronal destruction and increased sensitivity of pain receptors [3].

The risk factors for herpes zoster in children are not clearly known. Some cases of pediatric herpes zoster have been reported in infants with maternal chickenpox during pregnancy [4].

The particularity of the child’s form is the predominance of general signs, the generally favorable evolution, and post-herpetic pain, which remains exceptional [5–7].

Albeit herpes zoster is quite rare in the pediatric population, and especially with the introduction and democratization of the chickenpox vaccine, we ought to take it into consideration when faced with a painful vesicular eruption following a dermatome.

The particularity of our observation was the occurrence of herpes zoster in an immunocompetent and fully vaccinated child without any notion of previous chickenpox infection, which remains a rare form in children.

REFERENCES

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2. Weinmann S, Naleway AL, Koppolu P, Baxter R, Belongia EA, Hambidge SJ, et al. Incidence of herpes zoster among children:2003-2014. Pediatrics. 2019;144:20182917.

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