History and exam

Key diagnostic factors

common

presence of risk factors

Key risk factors include: exposure to varicella, young age, immunisation status, and occupation.

fever

Usually <38°C (101.5°F), but may be as high as 41°C (106°F).[6]

Secondary bacterial infection should be considered in patients with persistent (i.e., >3 days) or recurrent fever.

vesicular rash

Classically described as a dew drop on a rose petal. The rash usually first appears centrally (on the face, scalp, or torso), before spreading to the extremities.[62]

Lesions first appear as macules and quickly develop into fluid-filled vesicles.

As the disease progresses, early lesions will begin to scab over as new peripheral lesions develop. This appearance of lesions in 'crops' (i.e., different stages of acuity/healing) is characteristic of varicella.

[Figure caption and citation for the preceding image starts]: Typical vesicular rash of primary varicella; note that lesions are in different stagesImage provided by the CDC and the Public Health Image Library [Citation ends].com.bmj.content.model.Caption@1008e3a6[Figure caption and citation for the preceding image starts]: Varicella lesions in different stages of healingImage provided by the CDC [Citation ends].com.bmj.content.model.Caption@3a18bde2

vesicles on mucous membranes

Found most commonly in nasopharynx, but also on other mucous membranes such as conjunctiva, mouth, and vulva. [Figure caption and citation for the preceding image starts]: Varicella lesion on the hard palate of a young patientImage provided by the CDC and the Public Health Image Library [Citation ends].com.bmj.content.model.Caption@52c3cae1

Other diagnostic factors

common

pruritus

May be a feature in some patients prior to the onset of the rash.

headache

May be a feature in some patients prior to the onset of the rash.

fatigue/malaise

May be a feature in some patients prior to the onset of the rash.

sore throat

May be a feature in some patients prior to the onset of the rash.

tachycardia

May be present in infected patients.

Risk factors

strong

exposure to varicella

Occurs through family contacts or day care- or school-related exposure.

age 1 to 9 years

Most common at-risk group is children aged 1 to 9.

unimmunised status

While previous immunisation does not rule out varicella, it markedly decreases the risk of acquisition and appears to attenuate the disease presentation in those with breakthrough varicella.[15][16]​​

occupational exposure

Adults with occupational exposure to children, people admitted to hospital, military recruits, or other high-density at-risk populations are at higher risk for acquiring varicella.[17][18]

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