Vasogenic Edema Covering the Brain Surface in a Case of Severe Meningoencephalitis Due to Varicella-Zoster Virus Infection.

Meningoencephalitis caused by varicella-zoster virus (VZV) is a serious condition requiring prompt antiviral treatments, but magnetic resonance imaging (MRI) findings are often normal, limiting early diagnostic utility. We report a case of severe VZV-associated meningoencephalitis characterized by diffuse T2 hyperintense lesions covering the brain surface on MRI, presumed to be vasogenic edema. An immunocompetent 78-year-old Japanese woman presented with a disturbance of consciousness preceded by seven days of headache. On admission, she was in a semi-coma with intermittent convulsive seizures and had a localized skin rash with blisters on her back. Brain MRI showed diffuse T2 hyperintensity on the brain surface with an elevated apparent diffusion coefficient and the marked gadolinium-contrast enhancement of the pia-arachnoid membrane and vessel walls. Polymerase chain reaction using cerebrospinal fluid revealed the presence of VZV, and then she was diagnosed with VZV-associated meningoencephalitis. Treatment with acyclovir and corticosteroids was initiated, leading to some clinical improvement; however, the patient developed acute non-occlusive mesenteric ischemia and died on the 10th day of hospitalization. The characteristic MRI findings observed in our patient may be useful in considering the pathogenesis and early diagnosis of this rare entity.

"Bloomy rind sign" in varicella-zoster virus brainstem meningoencephalitis.

The bloomy rind sign, characterized by band-like abnormalities along the surface of the brainstem on magnetic resonance imaging without contrast enhancement, has been considered a specific imaging marker for leptomeningeal metastasis from lung adenocarcinoma. In this study, we describe the case of an 85-year-old male with a 3-week history of headache, fever, and progressive cognitive impairment. The patient was diagnosed with varicella-zoster virus brainstem meningoencephalitis and magnetic resonance imaging revealed hyperintensities along the brainstem surface on fluid-attenuated inversion recovery and diffusion-weighted imaging that mimicked a bloomy rind sign. However, the patient showed no signs of lung cancer or meningeal carcinomatosis. This case suggests that the bloomy rind sign is not exclusive to leptomeningeal metastasis but can also be observed in other conditions, such as central nervous system infections.

Seroprevalence of human herpes viruses in France, 2018-2022: a multilevel regression and poststratification approach.

BACKGROUND: Information related to herpes simplex virus 1 and 2 (HSV-1 and 2), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), and cytomegalovirus (CMV) seroprevalence in France is either lacking, incomplete, or outdated, despite their public health burden. METHOD: We used routinely collected serological data between 2018 and 2022 to estimate HSV-1, HSV-2, VZV, EBV, and CMV seroprevalence in France. To account for demographic differences between our analytic samples and the French population and get estimates for sparsely sampled districts and age classes, we used a multilevel regression and poststratification approach combined with Bayesian model averaging via stacking weights. RESULTS: The observed seroprevalence (number of positive tests/number of tests) were 64.6% (93,294/144,424), 16.9% (24,316/144,159), 93.0% (141,419/152,084), 83.4% (63,199/75, 781), and 49.0% (23,276/47,525), respectively, for HSV-1, HSV-2, VZV, EBV, and CMV. Between 2018 and 2022, France had a model-based average (equal-tailed interval at 95%) expected seroprevalence equal to 61.1% (60.7,61.5), 14.5% (14.2,14.81), 89.5% (89.3,89.8), 85.6% (85.2,86.0), and 50.5% (49.3,51.7), respectively, for HSV-1, HSV-2, VZV, EBV, and CMV infections. We found an almost certain lower expected seroprevalence in Metropolitan France than in overseas territories for all viruses but VZV, for which it was almost certainly greater. The expected seroprevalences were likely greater among females for all viruses. LIMITATIONS: Our results relied on the assumption that individuals were sampled at random conditionally to variables used to build the poststratification table. IMPLICATIONS: The analysis highlights spatial and demographic patterns in seroprevalence that should be considered for designing tailored public health policies.

New Insights Into the Therapeutic Management of Varicella Zoster Virus Meningitis: A Series of 123 Polymerase Chain Reaction-Confirmed Cases.

Background: Varicella zoster virus (VZV) can reactivate and cause meningitis, but few studies have distinguished it from meningoencephalitis regarding treatment recommendations.The objective of this study was to assess the outcomes of a large series of patients with VZV meningitis according to their therapeutic management. Methods: We conducted a bicentric retrospective cohort study, in Paris, France, including all adult patients with a cerebrospinal fluid sample positive for VZV by polymerase chain reaction between April 2014 and June 2022. We distinguished meningitis from encephalitis according to the International Encephalitis Consortium criteria. Unfavorable outcome was defined as mortality or functional sequelae defined by a loss of 2 points on the modified Rankin Scale. Results: We included 123 patients with meningitis. Among them, 14% received no antivirals, while 20% were treated with oral valacyclovir alone, 41% with a short course of intravenous (IV) acyclovir before switch to valacyclovir, and 25% with a long course of IV acyclovir. Outcomes were favorable regardless of antiviral regimen. In multivariate analysis, only age, underlying immunosuppression, and cranial radiculitis appear to be predictive factors for longer IV therapy, based on the Akaike information criterion. Conclusions: In this study, patients with VZV meningitis had a good outcome, with no evidence of any impact of the treatment strategy. However, further studies are needed to support the possibility of milder treatment in immunocompetent patients, avoiding cost and side effects of IV acyclovir.

Intravenous Immunoglobulin and Intravenous Acyclovir as an Alternative Therapy to Varicella Zoster Immunoglobulin in the Prevention of Serious Complications of Neonatal Varicella.

Neonatal varicella, arising from maternal infection with the varicella-zoster virus (VZV), is a rare but potentially severe condition with diverse clinical presentations. This case report highlights an instance where the mother developed a maculopapular rash seven days before delivery, indicating a possible transmission of VZV to the neonate. The patient's family history included recent diagnoses of herpes zoster and varicella among household members. On the second day of life, the newborn developed a discrete vesicular rash on an erythematous background, affecting the trunk and neck. Due to the unavailability of varicella zoster immunoglobulin (VZIG), intravenous immunoglobulin (IVIG) was administered along with a seven-day course of intravenous acyclovir. Despite the absence of VZIG, the combined treatment with IVIG and acyclovir proved effective in resolving the rash by the sixth day of life, without any ensuing complications. This case underscores the challenges of managing neonatal varicella in resource-limited settings and suggests that combination therapy may not prevent the occurrence of neonatal varicella but can mitigate serious complications and expedite clinical recovery.

Primary Varicella Infection in a Young Adult from the Democratic Republic of the Congo: A Case Report and Mini-Review.

We describe a case of an immunocompetent adult male patient originally from the Democratic Republic of Congo (DRC), who was referred to our unit for a several-day history of fever and a pruritic, vesicular rash. There was initial concern in the Emergency Department for Mpox (formerly known as "monkeypox") given the current epidemiology versus other viral etiologies. Primary varicella zoster virus (pVZV) infection was ultimately diagnosed by PCR from a swabbed, unroofed lesion, and he recovered completely with supportive management and without antiviral therapy. We herein describe how common viral exanthems may best be differentiated in an emergency or outpatient setting.

Seroprevalence of antibodies against varicella zoster virus across all age groups during the post-COVID-19 pandemic period in Chonburi Province, Thailand.

As of 2024, Thailand has not incorporated the varicella-zoster virus (VZV) vaccine into the Expanded Program on Immunization (EPI). This study aimed to evaluate VZV seroprevalence across all age groups in Chonburi Province, Thailand, during the post-COVID-19 era, and to support the development of a vaccination plan against VZV. A total of 950 participants were enrolled from October 2022 to January 2023. VZV antibody levels were measured using ELISA kits (EUROIMMUN, Lübeck, Germany), with seropositivity set at ≥110 IU/L. The overall VZV seropositivity rate was 64.8%, similar to rates in 1994 and 2014. However, seropositivity rates for the 5-9, 10-14, and 15-19 age groups were significantly higher in the 1994 study, and for the 10-14 and 15-19 age groups in the 2014 study, indicating a declining trend among young Thai individuals. The seropositivity rate increased with age, with a seroprevalence exceeding 80% in individuals aged 30 years and older. Our study found a significant association between the history of varicella and seropositivity. Thus, a positive history may indicate immunity. In conclusion, a significant portion of Thai adolescents are still vulnerable to varicella, highlighting the crucial role of vaccination in averting serious illness.

A Review of Atypical Cutaneous Histological Manifestations of Herpes Zoster.

The clinical and histopathological features of herpes zoster (HZ) are usually straightforward. Atypical histological presentations, in the absence of the classical viral cytopathic changes, are well documented and can make the diagnosis of HZ extremely difficult. Herein, we review the existing literature on atypical cutaneous histological manifestations of the disease, with emphasis on the subtle clues, use of immunohistochemistry, and potential pitfalls.

A unique case of double meningitis with enterovirus and reactivated varicella-zoster virus in a male teenager.

This paper presents a unique case of double meningitis with enterovirus and reactivated varicella-zoster virus without shingles in an immunocompetent male teenager, a case that offers many important medical lessons, all "gravitating" around physiopathological reasoning of any clinical case in general.

Suppression of the host antiviral response by non-infectious varicella zoster virus extracellular vesicles.

Varicella zoster virus (VZV) reactivates from ganglionic sensory neurons to produce herpes zoster (shingles) in a unilateral dermatomal distribution, typically in the thoracic region. Reactivation not only heightens the risk of stroke and other neurological complications but also increases susceptibility to co-infections with various viral and bacterial pathogens at sites distant from the original infection. The mechanism by which VZV results in complications remote from the initial foci remains unclear. Small extracellular vesicles (sEVs) are membranous signaling structures that can deliver proteins and nucleic acids to modify the function of distal cells and tissues during normal physiological conditions. Although viruses have been documented to exploit the sEV machinery to propagate infection, the role of non-infectious sEVs released from VZV-infected neurons in viral spread and disease has not been studied. Using multi-omic approaches, we characterized the content of sEVs released from VZV-infected human sensory neurons (VZV sEVs). One viral protein was detected (immediate-early 62), as well as numerous immunosuppressive and vascular disease-associated host proteins and miRNAs that were absent in sEVs from uninfected neurons. Notably, VZV sEVs are non-infectious yet transcriptionally altered primary human cells, suppressing the antiviral type 1 interferon response and promoting neuroinvasion of a secondary pathogen in vivo. These results challenge our understanding of VZV infection, proposing that the virus may contribute to distant pathologies through non-infectious sEVs beyond the primary infection site. Furthermore, this study provides a previously undescribed immune-evasion mechanism induced by VZV that highlights the significance of non-infectious sEVs in early VZV pathogenesis. IMPORTANCE: Varicella zoster virus (VZV) is a ubiquitous human virus that predominantly spreads by direct cell-cell contact and requires efficient and immediate host immune evasion strategies to spread. The mechanisms of immune evasion prior to virion entry have not been fully elucidated and represent a critical gap in our complete understanding of VZV pathogenesis. This study describes a previously unreported antiviral evasion strategy employed by VZV through the exploitation of the infected host cell's small extracellular vesicle (sEV) machinery. These findings suggest that non-infectious VZV sEVs could travel throughout the body, affecting cells remote from the site of infection and challenging the current understanding of VZV clinical disease, which has focused on local effects and direct infection. The significance of these sEVs in early VZV pathogenesis highlights the importance of further investigating their role in viral spread and secondary disease development to reduce systemic complications following VZV infections.

Reduced unilateral sweating caused by varicella zoster virus infection: a case report.

BACKGROUND: Herpes zoster is an infectious skin disease caused by the reactivation of the varicella zoster virus (VZV), which has been latent in the posterior root ganglia of the spinal cord or cranial ganglia for an extended period. Neurological complications caused by herpes zoster include aseptic meningitis, white matter disease, peripheral motor neuropathy, and Guillain-Barré syndrome. However, reduced unilateral sweating caused by the VZV is very rare. CASE PRESENTATION: This article reports the case of a 34-year-old woman who was admitted to our hospital with sore throat, dizziness, and reduced sweating on the left side of her body. Physical examination found herpes lesions on the left upper lip and left external ear canal (scabbed) and reduced sweating on the left side of the body. Head magnetic resonance imaging (MRI) with contrast showed no abnormalities. After a lumbar puncture, the patient was diagnosed with viral meningitis by VZV infection. The electromyographic skin sympathetic reflex indicated damage to the left sympathetic nerve. CONCLUSIONS: Secondary unilateral sweating reduction is a rare neurological complication of herpes zoster, caused by damage to the autonomic nervous system. Literature review and comprehensive examination indicated that the reduced unilateral sweating was due to the activation of latent herpes zoster virus in the autonomic ganglia which has damaged the autonomic nervous system. For patients who exhibit acute hemibody sweat reduction, doctors should consider the possibility of secondary autonomic nervous system damage caused by herpes zoster.

[A case of a young woman with bilateral medial medullary infarcts caused by varicella-zoster virus vasculopathy without skin rash].

The patient, a 36-year-old female, had no previous history of shingles. She was admitted to the hospital due to nausea and lightheadedness. Upon admission, she was diagnosed with bilateral medial medullary infarcts. She received treatment with intravenous edaravone and argatroban, as well as antiplatelet therapy with aspirin and clopidogrel. However, her dysphagia, dysarthria, and paraplegia worsened. Due to changes in the lesion of the basilar artery on brain |MRA, we suspected the possibility of basilar artery dissection, and discontinued antiplatelet therapy. Subsequent imaging studies suggested vasculitis. After examining the cerebrospinal fluid, we diagnosed varicella-zoster virus (VZV) vasculopathy. Based on this diagnosis, we administered steroid pulse therapy for three days, started intravenous acyclovir, and resumed antithrombotic therapy with clopidogrel. Prednisone was administered for five days. Biochemical tests revealed an elevated D-dimer level. Due to the presence of lower extremity venous thrombus, clopidogrel was replaced with apixaban. The acyclovir infusion was discontinued due to observed acyclovir-induced neutropenia. These treatments improved neurological symptoms, circumflex thickening of the basilar artery, and contrast effects in the same area. On the 70th day, the patient was transferred to the hospital for rehabilitation. It is important to consider VZV angiopathy as a potential cause of juvenile cerebral infarction accompanying progressive basilar artery stenosis, regardless of the presence or absence of a skin rash.

Rare presentation of maxillary osteonecrosis and tooth exfoliation induced by herpes zoster infection in a 29-year-old Chinese male: a case report and literature review.

BACKGROUND: We present a case of a 29-year-old male patient without immunodeficiency who suffered from rapid osteonecrosis and tooth exfoliation resulting from herpes zoster (HZ) infection in the left maxillary branch of the trigeminal nerve. Various complications associated with shingles infections have been reported, cases of osteonecrosis and tooth exfoliation due to HZ infection among young people without immunodeficiency are rare. In this case, we focus on the particular manifestation of HZ infection. CASE PRESENTATION: The patient presented with clusters of erythema and papules, along with non-hemorrhagic blisters on the left face and the loss of the left upper incisor. All lesions were localized to the left side of the face without exceeding the midline. After receiving antibacterial and antiviral treatment, successful control over the infection was achieved; however, he experienced the loss of all upper teeth on the left side except for the first and second upper left molars. CONCLUSION: This case highlights that rapid osteonecrosis and tooth exfoliation may occur among young individuals without immunodeficiency after HZ infection. HZ infection of the face should be taken very seriously to obtain prompt treatment to prevent the rare complications of bone necrosis and tooth loss as much as possible.

A Single-Center Case Series of Acute Retinal Necrosis at Teikyo University: Clinical Characteristics and Treatment Outcomes.

Aim To evaluate the clinical characteristics, treatment course, and prognosis of patients with acute retinal necrosis (ARN), which can rapidly progress and cause severe vision loss. Design Single-center retrospective case series. Subjects and methods Six patients and seven eyes diagnosed with ARN at Teikyo University Hospital were included in this study. The clinical presentation and treatment prognosis were investigated based on data obtained from medical records. Results The mean age of the patients at the initial diagnosis was 63.6 years. Although the mean Logarithm of the Minimum Angle of Resolution (LogMAR) visual acuity tended to decrease from 0.77 at the first visit to 1.29 at the last visit, the difference was not statistically significant. Intraocular manifestations observed during the study period included ocular hypertension (14.3%), anterior uveitis (100.0%), retinal hemorrhage (71.4%), vitreous opacity (100.0%), retinal exudative vasculitis (85.7%), optic nerve atrophy (85.7%), retinal vascular occlusion (85.7%), choroidal atrophy (85.7%), macular edema (100.0%), subretinal fluid in the macula (71.4%), and retinal detachment (85.7%). Treatment modalities included oral and intravitreal antivirals (85.7%), antiplatelet medications (85.7%), steroid eye drops (85.7%), subcapsular (57.1%) and vitreous (42.9%) steroid injections, oral steroids (71.4%), and surgical intervention (85.7%). Vitrectomy led to retinal recovery in all five eyes that underwent the procedure. Conclusions The visual prognosis of patients with ARN is poor, particularly in those with preexisting visual impairment. Early detection coupled with antiviral therapy and prompt surgical intervention have been identified as potential factors that influence visual outcomes. Given the severity of ARN, collecting data from multiple centers could aid in devising future diagnostic and therapeutic strategies.

Herpes Zoster Infection of Orofacial Region in a Geriatric Patient: A Case Report.

The varicella-zoster virus reactivates to cause the "herpes zoster" (HZ). ''Varicella-zoster virus'' (VZV) termed as ''HHV-3'' or ''human herpesvirus-3'' infection causes herpes zoster. Varicella, the primary form of the virus, is chickenpox, and the secondary form of the virus is herpes zoster also called shingles. During prior chicken pox episodes, this virus enters the body through cutaneous nerve endings and becomes dormant in the dorsal root ganglia. It sometimes affects the orofacial region and appears as unilaterally distributed burning pain, multiple, painful vesicular lesions, and ulcerations. Immunocompromised people are more likely to have disseminated zoster, which is defined as the involvement of three or more dermatomes. These are most likely to occur in elderly, immunocompromised patients, patients undergoing cancer chemotherapy, patients on immunosuppressants, and patients suffering from AIDS. This is a study of a male geriatric patient, aged 74 years, who reported unilateral pain, swelling, as well as multiple ulcerations on the left side of his face, extraorally as well as intraorally. The case was diagnosed as a herpes zoster infection involving V1 and V2 dermatome of the trigeminal nerve.

Varicella Zoster Virus Vasculopathy: An Under-Recognized Entity.

Varicella zoster virus (VZV) vasculopathy is a rare yet potentially severe neurological manifestation resulting from VZV reactivation, primarily affecting immunocompromised individuals. We present a case report of a 61-year-old male with VZV vasculopathy who initially presented with herpes zoster ophthalmicus, subsequently complicated by meningoencephalitis and an acute infarct in the territory of the left middle cerebral artery (MCA). Imaging revealed acute and chronic infarcts in the capsuloganglionic regions, accompanied by thickening and enhancement of the left MCA wall. Treatment involved a 14-day course of intravenous acyclovir, supplemented with oral prednisolone, resulting in modest clinical improvement. VZV vasculopathy represents an infrequently acknowledged neurological syndrome, particularly prevalent among immunocompromised individuals. Early recognition and appropriate intervention offer promise in ameliorating outcomes for affected patients. This case emphasizes the importance of including VZV vasculopathy in the differential diagnosis of neurological deficits, especially within high-risk populations.

Eczema exacerbation following herpes zoster infection in an immunocompetent patient: A case report.

This case report highlights a severe eczematous rash manifesting broadly across the scalp, face, and neck of a 54-year-old female following a resolved herpes zoster infection. Notably, such cutaneous reactions post-varicella zoster virus infection, which may present weeks to years after the acute phase, have been documented but remain poorly understood in their pathogenesis. This patient exhibited a blistering rash diagnosed as shingles with overlying cellulitis, initially treated with valacyclovir and cefalexin. Upon returning with a diffuse rash post-treatment, further examination and tests led to a differential diagnosis that most closely aligned with eczema exacerbation with superimposed bacterial infection, confirmed by the presence of methicillin-resistant Staphylococcus aureus. Treatment encompassed intravenous vancomycin, ciprofloxacin eye drops, topical hydrocortisone, betamethasone lotion, and gabapentin, leading to substantial improvement. This case underscores the complexity of diagnosing and managing cutaneous reactions post-varicella zoster virus infection and suggests a multimodal treatment approach may yield favorable outcomes.

A holistic exploration of the optimal control strategies on an enhanced mathematical model for the co-infection of HIV/AIDS and varicella-zoster.

Because of its high contagiousness and correlation with HIV/AIDS complaints, the virus that causes varicella-zoster virus and its interactions have major consequences for a considerable portion of people worldwide. The primary aim of this work is to suggest and examine optimal control methods for managing the transmission dynamics of HIV/AIDS and Varicella-Zoster co-infection, using an integer model approach. The mathematical analyses of the proposed integer order model places particular emphases on the boundedness and non-negativity of the model solutions, scrutinizing equilibrium points, determining the models basic reproduction ratios (the models basic reproduction numbers) through the next-generation matrix operator method, and assessing the model equilibrium points existences and stabilities in local approach by considering the local stability conditions of Routh and Hurwitz. Additionally, it incorporates an optimal control framework to enhance our understanding of the dynamics involved in the spreading of HIV/AIDS and Varicella-Zoster co-infection within a considered population. This entails determining preventative measures that can be deliberately put into place to lessen the effects of these co-infections. The solutions of the HIV/AIDS and Varicella-Zoster co-infection model converges to the co-infection endemic equilibrium point whenever the associated basic reproduction number is greater than unity, as verified by numerical simulation results. Including optimal management gives the research an innovative viewpoint and helps identify tactical ways to mitigate the negative effects of this co-infection on the public health. The results highlight how crucial it is to address these complex structures in order to protect and improve public health outcomes. Implementing the proposed protection measures and treatment measures simultaneously has most effective result to minimize and eliminate the HIV/AIDS and Varicella-Zoster co-infection disease throughout the population.

Varicella-Zoster Virus-Induced Neurologic Disease After COVID-19 Vaccination: A Multicenter Observational Cohort Study.

Background: Early reports described an increased risk of herpes zoster following receipt of mRNA-based COVID-19 vaccines. The objective was to assess whether COVID-19 vaccine is associated with varicella-zoster virus-induced neurologic disease (VZV-ND). Methods: This multicenter retrospective case-control study with a test-negative design was conducted at 12 hospitals in Israel. We included all patients admitted with VZV-ND between January 2020 and December 2021 and matched controls with a negative polymerase chain reaction result for VZV in cerebrospinal fluid. Results: We identified 188 patients meeting the case definition of VZV-ND who were admitted during the study period. Cases were matched with 376 controls. There was no significant variation in the incidence of VZV-ND between 1 year preceding and 1 year following the deployment of BNT162b2 in Israel. Analysis of persons who had received at least 1 dose of COVID-19 vaccine (n = 259) showed similar proportions of VZV-ND and non-VZV-ND in 4 intervals (30, 42, 50, 60 days) following the last vaccine dose. The median time from the last vaccine dose to hospitalization with a neurologic syndrome was 53 days (IQR, 25-128) and 82 days (IQR, 36-132) for VZV-ND and non-VZV-ND, respectively, not reaching statistical significance (P = .056). The rate of VZV-ND in vaccinated patients was no different from the rate in the unvaccinated group (30.9% vs 35.4%, P = .2). Conclusions: We did not find an association between COVID-19 vaccine and VZV-ND. Since COVID-19 vaccine is now recommended yearly, every fall and winter, establishing the safety of the vaccine is of great importance.

Varicella-Zoster Virus Reactivation After Pediatric Allogeneic Hematopoietic Stem Cell Transplantation, Single-Center Experience of Acyclovir Prophylaxis.

BACKGROUND: Varicella-zoster virus (VZV) reactivation is the most common infectious complication in the late posthematopoietic stem cell transplantation (HSCT) period and is reported as 16%-41%. Acyclovir prophylaxis is recommended for at least 1 year after HSCT to prevent VZV infections. However, studies on the most appropriate prophylaxis are ongoing in pediatric patients. METHODS: Patients who underwent allogeneic HSCT between January 1, 1996 and January 1, 2020 were retrospectively analyzed to outline the characteristics of VZV reactivation after allogeneic HSCT in pediatric patients using 6 months acyclovir prophylaxis. RESULTS: There were 260 patients and 273 HSCTs. Median age was 10.43 (0.47-18.38), and 56% was male. Median follow-up was 2325 days (18-7579 days). VZV reactivation occurred in 21.2% (n = 58) at a median of 354 (55-3433) days post-HSCT. The peak incidence was 6-12 months post-HSCT (43.1%). Older age at HSCT, female gender, history of varicella infection, lack of varicella vaccination, low lymphocyte, CD4 count, and CD4/CD8 ratio at 9 and 12 months post-HSCT was found as a significant risk for herpes zoster (HZ) in univariate analysis, whereas history of varicella infection and low CD4/CD8 ratio at 12 months post-HSCT was an independent risk factor in multivariate analysis. CONCLUSIONS: Tailoring acyclovir prophylaxis according to pre-HCT varicella history, posttransplant CD4 T lymphocyte counts and functions, and ongoing immunosuppression may help to reduce HZ-related morbidity and mortality.