Complicated varicella

Complicated varicella refers to varicella-zoster virus infection with clinically significant complications rather than an uncomplicated exanthem alone ^[1][2]. In the available sources, complicated disease is linked to severe presentations such as varicella pneumonia in adults and a range of neurologic or disseminated complications in children ^[1][2]. Source-backed detail on formal case definition criteria or standardized severity thresholds is not yet available.

The cited literature describes complicated varicella as potentially serious and, in adults, often associated with symptomatic varicella pneumonia ^[1]. In a pediatric case series, complications included encephalitis, cerebellar ataxia, aseptic meningitis with cerebellar ataxia, glomerulonephritis with secondary skin infection, and disseminated infection with hemorrhagic vesicles, hepatitis, ileus, mesenteric adenitis, and disseminated intravascular coagulation ^[2]. One disseminated case was fatal after a severe course, and one encephalitis case left behavioral problems and poor memory, indicating that both acute mortality and residual sequelae can occur ^[2]. The sources do not provide a comprehensive symptom profile beyond these severe manifestations.

The sources characterize complicated varicella as infrequent but clinically important, including in immunocompetent adults ^[1]. Pediatric oncology literature highlights elevated varicella-zoster virus-associated morbidity and mortality in children with cancer, although death from varicella during cancer treatment is described as rare ^[3]. A case series also shows that serious complications can occur in previously healthy children without underlying immunodeficiency ^[2]. Geographic distribution and population-level burden are not quantified in the provided material, and source-backed detail on trends over time is not yet available.

The available sources do not describe transmission in mechanistic detail for complicated varicella specifically. They do note the importance of reducing varicella-zoster virus exposure among seronegative individuals, implying that exposure prevention is relevant to surveillance and control ^[3]. Source-backed detail on specific routes, duration of infectiousness, or environmental persistence is not yet available.

The sources specifically identify immunocompetent adults as a group in whom varicella may be infrequent but potentially serious, with complicated disease often presenting as varicella pneumonia ^[1]. Children with cancer are highlighted as a high-risk group for VZV-associated morbidity and mortality, and the literature on postexposure prophylaxis focuses on this population ^[3]. Complicated disease is also documented in previously healthy children without underlying immunodeficiency, showing that absence of known immunodeficiency does not exclude severe outcomes ^[2]. Source-backed detail on additional risk groups is not yet available.

Prevention in the cited literature centers on limiting exposure and using postexposure prophylaxis in selected settings ^[3]. In children with malignancy, early administration of varicella zoster immune globulin is generally described as protective against severe and complicated varicella, while some centers instead use oral aciclovir as postexposure prophylaxis ^[3]. The same review states that vaccination of healthy susceptible family contacts of children with malignancy is supported, although vaccination of the patients themselves is not ^[3]. Source-backed detail on routine population-level prevention measures beyond these points is not yet available.

For surveillance purposes, complicated varicella should be read as a marker of clinically severe varicella-zoster virus disease rather than routine varicella occurrence. The sources show that cases may present with neurologic involvement, pneumonia, disseminated infection, organ dysfunction, or death, and that such complications may arise in both immunocompetent and immunocompromised hosts ^[1][3][2]. Because the cited literature does not define a single standardized surveillance threshold, interpretation should remain anchored to documented complications rather than presumed severity. The evidence base also indicates that prevention practices in exposed high-risk groups are clinically relevant to monitoring and control ^[3].

1. 1 Wallace MR et al. Treatment of varicella in the immunocompetent adult. J Med Virol. 1993. PMID: 8245900. doi: 10.1002/jmv.1890410517. PubMed: https://pubmed.ncbi.nlm.nih.gov/8245900/
2. 2 Phuah HK et al. Complicated varicella zoster infection in 8 paediatric patients and review of literature. Singapore Med J. 1998 Mar. PMID: 9632970. PubMed: https://pubmed.ncbi.nlm.nih.gov/9632970/
3. 3 Fisher JP et al. Preventing varicella in children with malignancies: what is the evidence? Curr Opin Infect Dis. 2011 Jun. PMID: 21455062. doi: 10.1097/QCO.0b013e328345d666. PubMed: https://pubmed.ncbi.nlm.nih.gov/21455062/
4. 4 Corticosteroids: no association with complicated varicella. Reactions Weekly. 1996. doi: 10.2165/00128415-199606000-00009. DOI: https://doi.org/10.2165/00128415-199606000-00009
5. 5 Corticosteroids and Risk of Complicated Varicella. Archives of Pediatrics & Adolescent Medicine. 1996. doi: 10.1001/archpedi.1996.02170370092020. DOI: https://doi.org/10.1001/archpedi.1996.02170370092020
6. 6 Varicella Infection Complicated by Marked Thrombocytopenia. Japanese Journal of Infectious Diseases. 2014. doi: 10.7883/yoken.67.292. DOI: https://doi.org/10.7883/yoken.67.292

ICD-10

B01

ICD-11

KA62.0

Total cases

658

Peak month

2025-04

Coverage

1 reporting countries · 2013-12-01 → 2026-05-01