Complications
Most commonly reported complication.[57] Associated with Staphylococcus aureus and group A streptococcus (GAS) infection.[96] Key feature is fever that persists (or recurs) beyond 3 days of the primary rash.
Patients with localised or diffuse spreading skin erythema and/or persistent fever should be evaluated for infection and considered for empirical antibiotics.
Invasive GAS may lead to complications such as streptococcal toxic shock syndrome, necrotising fasciitis, myositis, and glomerulonephritis.[97]
Surgical consultation to evaluate for necrotising fasciitis should be requested in patients who present more than 2 or 3 days after the onset of rash with symptoms that include fever, tachycardia, and an elevated band count in association with erythematous, indurated, painful lesion(s).[98]
Data suggest an increased risk of bacterial skin infections in varicella following treatment with non-steroidal anti-inflammatory drugs, so these should be avoided during treatment.[78]
Uncommon in children; rates are higher in adolescents, adults, pregnant women, immunosuppressed people, and smokers.[99][100][101] It is the most common life-threatening complication in adults, affecting 1 in every 400 adults with varicella.[99][102] Adults are also more likely to develop haemorrhagic pulmonary disease.[5]
Pregnant women may be more likely to develop varicella pneumonia if they have 100 or more skin lesions and/or are known smokers.[103] Pregnant women who do develop pneumonia are at greater risk for death.[104]
Presents 1 to 6 days after the onset of the rash with cough, dyspnoea, tachypnoea, fever, and hypoxia, and sometimes with pleuritic chest pain or haemoptysis.[91][105]
Chest x-ray shows nodular or interstitial changes, often with a peribronchial distribution.[105][106]
Presents with headache and fever, but is most classically associated with an altered sensorium, and often occurs anywhere from 2 to 6 days after the onset of rash.[107] Immunocompromised patients may have varicella encephalitis without rash.[108]
May develop into generalised seizures, nuchal rigidity, and other signs of meningeal involvement.
Cerebrospinal fluid typically demonstrates elevated total protein and lymphocytic pleocytosis.[64]
Most common neurological complication in children below 15 years of age, occurring in 1 in 4000 children.[99] Presents with broad-based gait disturbance that occurs over the course of a few days. Associated symptoms can include irritability, vomiting, tremor, headache, and, rarely, nystagmus, slurred speech, hypotonia, and nuchal rigidity.[64]
Cerebrospinal fluid (CSF) examination is usually normal, but may be associated with increased CSF protein concentration.
Complete recovery occurs by 2 to 4 weeks, and long-term complications are rare.[109]
Mild sub-clinical hepatitis is common in immunocompetent children, is associated with mild increases in liver enzymes, and recovers uneventfully.[112][113]
Symptomatic hepatitis is a rare complication, found mainly in immunosuppressed patients; it is associated with marked elevation in liver enzymes and coagulopathy.[114]
Women who develop varicella from 5 days to 2 days prior to delivery have a high risk (17% to 30%) of transmitting the virus to their newborn. Because of the absence of maternal immunity to varicella-zoster virus, these children are at risk for severe infection.[21]
Scarring, which can also be associated with keloid formation, occurs in about 19% of children at 1 year post-varicella and is most commonly found on the face.[115]
Transmission of varicella across the placenta can occur during maternal varicella infection in the first or second trimester of pregnancy, although it is rare.[61][116][117][118]
Fetal damage can occur during gestation. May present as cicatricial skin lesions, limb hypoplasia or paresis, microcephaly, and ophthalmic lesions.[61][119][120]
Associated with the use of aspirin or other salicylates. Presents with vomiting, encephalopathy, and metabolic disturbances such as hyperammonaemia and elevated liver enzymes.[77]
Since the fatality rate of children with this rare syndrome reaches up to 30%, aspirin and other salicylates are not recommended for use during varicella.
Up to one third of patients with primary varicella zoster will develop herpes zoster during their lifetime.[11] Typically associated with rash of dermatomal distribution, itching, and pain.
Patients receiving varicella immunisation may have lower rates than those who naturally acquire varicella-zoster virus.[121][122][123] In immunocompetent children, rates of herpes zoster have been shown to be reduced in those receiving immunisation when compared with those who acquire wild-type varicella infection.[124][125][126] Similarly, the risk of herpes zoster in immunocompromised children may also be less in those who have had varicella vaccine than in those who previously acquired wild-type varicella infection.[125][126][127][128] However, due to short-term follow-up in most of these studies, further epidemiological data are still needed to determine the long-term risk of herpes zoster in children and adults receiving vaccination.[122]
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