Chickenpox

Chickenpox is caused by primary infection with varicella zoster virus. Shingles is a reactivation of the dormant virus in dorsal root ganglion

Chickenpox is highly infectious

spread via the respiratory route
can be caught from someone with shingles
infectivity = 4 days before rash, until 5 days after the rash first appeared*
incubation period = 10-21 days

Clinical features (tend to be more severe in older children/adults)

fever initially
itchy, rash starting on head/trunk before spreading. Initially macular then papular then vesicular
systemic upset is usually mild

Management is supportive

keep cool, trim nails
calamine lotion
school exclusion: NICE state the following: Advise that the most infectious period is 1-2 days before the rash appears, but infectivity continues until all the lesions are dry and have crusted over (usually about 5 days after the onset of the rash).
immunocompromised patients and newborns with peripartum exposure should receive varicella zoster immunoglobulin (VZIG). If chickenpox develops then IV aciclovir should be considered

A common complication is secondary bacterial infection of the lesions

NSAIDs may increase this risk
whilst this commonly may manifest as a single infected lesion/small area of cellulitis, in a small number of patients invasive group A streptococcal soft tissue infections may occur resulting in necrotizing fasciitis

Rare complications include

pneumonia
encephalitis (cerebellar involvement may be seen)
disseminated haemorrhagic chickenpox
arthritis, nephritis and pancreatitis may very rarely be seen

Chest x-ray showing miliary opacities secondary to healed varicella pneumonia. Multiple tiny calcific miliary opacities noted throughout both lungs. These are of uniform size and dense suggesting calcification. There is no focal lung parenchymal mass or cavitating lesion seen. The appearances are characteristic for healed varicella pneumonia.

Diffuse calcifications of varying sizes are predominantly located in the hilar and basilar regions. These findings represent a long-term sequela of varicella pneumonia.

+PassMedicine Notes

Chickenpox is caused by primary infection with varicella zoster virus. Shingles is a reactivation of the dormant virus in dorsal root ganglion

Chickenpox is highly infectious

spread via the respiratory route
can be caught from someone with shingles
infectivity = 4 days before rash, until 5 days after the rash first appeared*
incubation period = 10-21 days

Clinical features (tend to be more severe in older children/adults)

fever initially
itchy, rash starting on head/trunk before spreading. Initially macular then papular then vesicular
systemic upset is usually mild

Management is supportive

keep cool, trim nails
calamine lotion
school exclusion: NICE state the following: Advise that the most infectious period is 1-2 days before the rash appears, but infectivity continues until all the lesions are dry and have crusted over (usually about 5 days after the onset of the rash).
immunocompromised patients and newborns with peripartum exposure should receive varicella zoster immunoglobulin (VZIG). If chickenpox develops then IV aciclovir should be considered

A common complication is secondary bacterial infection of the lesions

NSAIDs may increase this risk
whilst this commonly may manifest as a single infected lesion/small area of cellulitis, in a small number of patients invasive group A streptococcal soft tissue infections may occur resulting in necrotizing fasciitis

Rare complications include