Neurological manifestations of Flaviviridae, Togaviridae, and Peribunyaviridae as vector-borne viruses.

Vector-borne viruses pose a significant health problem worldwide, as they are transmitted to humans through the bite of infected arthropods such as mosquitoes and ticks. In recent years, emerging and re-emerging vector-borne diseases have gained attention as they can cause a wide spectrum of neurological manifestations. The neurological manifestations of vector-borne viruses encompass a board spectrum of clinical manifestations, ranging from mild and self-limiting symptoms to severe and life-threatening conditions. Common neurological complications include viral encephalitis, acute flaccid paralysis, aseptic meningitis, and various neuromuscular disorders. The specific viruses responsible for these neurological sequelae vary by geographic region and include Orthoflavivirus nilense, Zika virus, dengue virus, chikungunya virus, Japanese encephalitis virus, and tick-borne encephalitis virus. This review focuses on the pathogenesis of these neurologic complications and highlights the mechanisms by which vector-borne viruses invade the central nervous system and trigger neuroinflammatory responses. Diagnostic challenges and strategies for early detection of neurological manifestations are discussed, emphasising the importance of clinical suspicion and advanced laboratory testing.

Serious neurological adverse events in immunocompetent children and adolescents caused by viral reactivation in the years following varicella vaccination.

Serious adverse events following vaccination include medical complications that require hospitalisation. The live varicella vaccine that was approved by the Food and Drug Administration in the United States in 1995 has an excellent safety record. Since the vaccine is a live virus, adverse events are more common in immunocompromised children who are vaccinated inadvertently. This review includes only serious adverse events in children considered to be immunocompetent. The serious adverse event called varicella vaccine meningitis was first reported in a hospitalised immunocompetent child in 2008. When we carried out a literature search, we found 15 cases of immunocompetent children and adolescents with varicella vaccine meningitis; the median age was 11 years. Eight of the children had received two varicella vaccinations. Most of the children also had a concomitant herpes zoster rash, although three did not. The children lived in the United States, Greece, Germany, Switzerland, and Japan. During our literature search, we found five additional cases of serious neurological events in immunocompetent children; these included 4 cases of progressive herpes zoster and one case of acute retinitis. Pulses of enteral corticosteroids as well as a lack of herpes simplex virus antibody may be risk factors for reactivation in immunocompetent children. All 20 children with adverse events were treated with acyclovir and recovered; 19 were hospitalised and one child was managed as an outpatient. Even though the number of neurological adverse events remains exceedingly low following varicella vaccination, we recommend documentation of those caused by the vaccine virus.

Benign recurrent lymphocytic meningitis (Mollaret's meningitis) in Denmark: a nationwide cohort study.

BACKGROUND AND PURPOSE: Data on clinical features and outcomes of benign recurrent lymphocytic meningitis (BRLM) are limited. METHODS: This was a nationwide population-based cohort study of all adults hospitalized for BRLM associated with herpes simplex virus type 2 (HSV-2) at the departments of infectious diseases in Denmark from 2015 to 2020. Patients with single-episode HSV-2 meningitis were included for comparison. RESULTS: Forty-seven patients with BRLM (mean annual incidence 1.2/1,000,000 adults) and 118 with single-episode HSV-2 meningitis were included. The progression risk from HSV-2 meningitis to BRLM was 22% (95% confidence interval [CI] 15%-30%). The proportion of patients with the triad of headache, neck stiffness and photophobia/hyperacusis was similar between BRLM and single-episode HSV-2 meningitis (16/43 [37%] vs. 46/103 [45%]; p = 0.41), whilst the median cerebrospinal fluid leukocyte count was lower in BRLM (221 cells vs. 398 cells; p = 0.02). Unfavourable functional outcomes (Glasgow Outcome Scale score of 1-4) were less frequent in BRLM at all post-discharge follow-up visits. During the study period, 10 (21%) patients with BRLM were hospitalized for an additional recurrence (annual rate 6%, 95% CI 3%-12%). The hazard ratio for an additional recurrence was 3.93 (95% CI 1.02-15.3) for patients with three or more previous episodes of meningitis. CONCLUSIONS: Clinical features of BRLM were similar to those of single-episode HSV-2 meningitis, whilst post-discharge outcomes were more favourable. Patients with three or more previous episodes of meningitis had higher risk of an additional recurrence.

Aseptic meningitis with recurrent headache episodes, vomiting, and central fever as first manifestation of isolated neurosarcoidosis: a case report.

BACKGROUND: Neurosarcoidosis is a rare entity, usually within the context of systematic sarcoidosis. Isolated neurosarcoidosis and especially a manifestation with pachymeningitis is a notable rarity. CASE REPORT: A 26-year-old patient presented to the emergency department with acute onset, recurrent episodes of occipital headaches spreading over the whole cranium and vomiting without food consumption, for three days. The clinical examination did not reveal any neurological deficits. The laboratory exams showed no pathological findings. A CT examination with angiography did not detect any acute intracranial or vessel pathology. A lumbar puncture was performed to rule out subarachnoid hemorrhage. The results showed a lymphocytic pleocytosis of 400/µL, elevated protein levels of 1077 mg/dL and reduced glucose levels (CSF: 55 mg/dL, Serum: 118 mg/dL). Extensive infectiological examinations did not reveal any signs of infection, including Borrelia spp. and M. tuberculosis. No positive auto-antibodies or vasculitis-related auto-antibodies were detected. The CSF analysis showed negative oligoclonal bands but an isolated increase in ß2-microglobulin, neopterin, and IL-2R levels. The MRI examination revealed a dural gadolinium-enhancement, pronounced in the basal cerebral structures and the upper segment of the cervical spine, consistent with neurosarcoidosis. Corticosteroid treatment rapidly led to a significant improvement of the symptoms. No systemic manifestations of sarcoidosis were found. CONCLUSIONS: This case report aims to highlight aseptic meningitis with atypical, acute onset headache attacks as a possible manifestation of isolated neurosarcoidosis. Neurosarcoidosis is a clinical entity that requires prompt treatment to avoid permanent neurological deficits.

Clinical features and prognostic factors in adults with viral meningitis.

Clinical features applicable to the entire spectrum of viral meningitis are limited, and prognostic factors for adverse outcomes are undetermined. This nationwide population-based prospective cohort study included all adults with presumed and microbiologically confirmed viral meningitis in Denmark from 2015 until 2020. Prognostic factors for an unfavourable outcome (Glasgow Outcome Scale score of 1-4) 30 days after discharge were examined by modified Poisson regression. In total, 1066 episodes of viral meningitis were included, yielding a mean annual incidence of 4.7 episodes per 100 000 persons. Pathogens were enteroviruses in 419/1066 (39%), herpes simplex virus type 2 in 171/1066 (16%), varicella-zoster virus in 162/1066 (15%), miscellaneous viruses in 31/1066 (3%) and remained unidentified in 283/1066 (27%). The median age was 33 years (IQR 27-44), and 576/1066 (54%) were females. In herpes simplex virus type 2 meningitis, 131/171 (77%) were females. Immunosuppression [32/162 (20%)] and shingles [90/149 (60%)] were frequent in varicella-zoster virus meningitis. The triad of headache, neck stiffness and hyperacusis or photophobia was present in 264/960 (28%). The median time until lumbar puncture was 3.0 h (IQR 1.3-7.1), and the median CSF leucocyte count was 160 cells/µl (IQR 60-358). The outcome was unfavourable in 216/1055 (20%) 30 days after discharge. Using unidentified pathogen as the reference, the adjusted relative risk of an unfavourable outcome was 1.34 (95% CI 0.95-1.88) for enteroviruses, 1.55 (95% CI 1.00-2.41) for herpes simplex virus type 2, 1.51 (95% CI 0.98-2.33) for varicella-zoster virus and 1.37 (95% CI 0.61-3.05) for miscellaneous viruses. The adjusted relative risk of an unfavourable outcome was 1.34 (95% CI 1.03-1.75) for females. Timing of acyclovir or valacyclovir was not associated with the outcome in meningitis caused by herpes simplex virus type 2 or varicella-zoster virus. In summary, the outcome of viral meningitis was similar among patients with different aetiologies, including those with presumed viral meningitis but without an identified pathogen. Females had an increased risk of an unfavourable outcome. Early antiviral treatment was not associated with an improved outcome in meningitis caused by herpes simplex virus type 2 or varicella-zoster virus.

Rheumatoid meningitis: a case series report and review of modern therapeutic schemes and outcome.

INTRODUCTION: Rheumatoid meningitis (RM) is an extremely rare extra-articular complication of rheumatoid arthritis (RA), with approximately 165 cases reported world-wide. RM exhibits a broad range of symptoms, with stroke-like episodes and seizures being the most common manifestations. The primary differential diagnoses include vascular and infectious diseases. The influence of immunomodulatory medications on the pathophysiology of RM remains unclear. There are no consensus guidelines on therapeutic regimen. METHODS: We present four patients with prior history of RA that developed different neurological syndromes in correlation to radiological leptomeningitis. Clinical presentations, comorbid conditions, supplementary diagnostic assessments, treatments, and prognosis are provided. A literature review of recent immunosuppressive management in RM patients was performed. RESULTS: Three patients presented to hospital with recurrent focal seizures. Only two suffered meningism, reporting headache and fever. Magnetic resonance imaging (MRI) showed different grades of leptomeningitis across all cases. Notably, three cases demonstrated bilateral involvement extending to the pachymeninges. Two patients exhibited pronounced CSF mononuclear inflammation while extended microbiological evaluations yielded negative results. Two patients required biopsy for confirmation. The initiation of immunosuppressive therapy marked a turning point for three patients who previously exhibited progressive deterioration. Mortality was absent in all cases. CONCLUSIONS: Our experience remarks the elusive nature of RM. Rigorous exclusionary diagnostics are imperative to differentiate RM from mimicking conditions. Clinical manifestations oscillate between transient episodes and progressive neurological impairments, punctuated by frequent epileptic seizures. In scenarios where clinical worsening persists or where clinical and radiological evaluations are inconclusive, aggressive immunosuppressive therapy is recommended.

Distinct patterns of postoperative fever in paediatric neurosurgery patients.

PURPOSE: Postoperative fever is a common problem following neurosurgery but data on the causes among paediatric patients is sparse. In this report, we determined the incidence, causes, and outcomes of postoperative fever in paediatric neurosurgical patients (< 18 years), and contrasted the findings with an adult cohort published recently from our unit. METHODS: We recruited 61 patients who underwent 73 surgeries for non-traumatic neurosurgical indications over 12 months. A standard protocol was followed for the evaluation and management of postoperative fever. We prospectively collected data pertaining to operative details, daily maximal temperature, clinical features, and use of surgical drains, urinary catheters, and other adjuncts. Elevated body temperature of > 99.9 °F or 37.7 °C for > 48 h or associated with clinical deterioration or localising features was considered as "fever"; elevated temperature not meeting these criteria was classified as transient elevation in temperature (TET). RESULTS: Twenty-six patients (35.6%) had postoperative fever, more frequent than in adult patients. TET occurred in 12 patients (16.4%). The most common causes of fever were aseptic meningitis (34.6%), followed by urinary tract infections (15.4%), pyogenic meningitis, COVID-19, and wound infections. Postoperative fever was associated with significantly longer duration of hospital admission and was the commonest cause of readmission. CONCLUSION: In contrast to adults, early temperature elevations in paediatric patients may portend infectious and serious non-infectious causes of fever, including delayed presentation with aseptic meningitis, a novel association among paediatric patients. Investigation guided by clinical assessment and conservative antibiotic policy in keeping with the institutional microbiological profile provides the most appropriate strategy in managing paediatric postoperative fever.

Drug-induced aseptic meningitis after an interlaminar lumbar epidural steroid injection.

BACKGROUND: This case report describes a rare instance of drug-induced aseptic meningitis after an interlaminar lumbar epidural steroid injection. CASE PRESENTATION: A 74 year-old female patient presented to the ED post-procedure day three after an L4-L5 interlaminar lumbar epidural steroid injection with fever, nausea, and vomiting. The patient had previously undergone numerous lumbar epidurals without complications and used identical medications, which included 1% lidocaine, iohexol contrast, methylprednisolone (Depo-medrol), and normal saline. Pertinent labs included a WBC of 15,000 cells/µL. Lumbar MRI revealed L4-S1 aseptic arachnoiditis. Two bone scans with Gallium and T-99 confirmed no infectious process. The patient then had a second admission months later with similar presenting symptoms and hospital course after repeating the lumbar epidural steroid injection. Lumbar MRI and CSF studies confirmed aseptic meningitis. CONCLUSION: This patient's repeated admissions from aseptic meningitis were likely caused by irritation of the meningeal layers from a medication used during the procedure.

An In Vivo Model of Echovirus-Induced Meningitis Defines the Differential Roles of Type I and Type III Interferon Signaling in Central Nervous System Infection.

Echoviruses are among the most common worldwide causes of aseptic meningitis, which can cause long-term sequelae and death, particularly in neonates. However, the mechanisms by which these viruses induce meningeal inflammation are poorly understood, owing at least in part to the lack of in vivo models that recapitulate this aspect of echovirus pathogenesis. Here, we developed an in vivo neonatal mouse model that recapitulates key aspects of echovirus-induced meningitis. We show that expression of the human homologue of the primary echovirus receptor, the neonatal Fc receptor (FcRn), is not sufficient for infection of the brains of neonatal mice. However, ablation of type I, but not III, interferon (IFN) signaling in mice expressing human FcRn permitted high levels of echovirus replication in the brain, with corresponding clinical symptoms, including delayed motor skills and hind-limb weakness. Using this model, we defined the immunological response of the brain to echovirus infection and identified key cytokines, such as granulocyte colony-stimulating factor (G-CSF) and interleukin 6 (IL-6), that were induced by this infection. Lastly, we showed that echoviruses specifically replicate in the leptomeninges, where they induce profound inflammation and cell death. Together, this work establishes an in vivo model of aseptic meningitis associated with echovirus infections that delineates the differential roles of type I and type III IFNs in echovirus-associated neuronal disease and defines the specificity of echoviral infections within the meninges. IMPORTANCE Echoviruses are among the most common worldwide causes of aseptic meningitis, which can cause long-term sequelae or even death. The mechanisms by which echoviruses infect the brain are poorly understood, largely owing to the lack of robust in vivo models that recapitulate this aspect of echovirus pathogenesis. Here, we establish a neonatal mouse model of echovirus-induced aseptic meningitis and show that expression of the human homologue of the FcRn, the primary receptor for echoviruses, and ablation of type I IFN signaling are required to recapitulate echovirus-induced meningitis and clinical disease. These findings provide key insights into the host factors that control echovirus-induced meningitis and a model that could be used to test anti-echovirus therapeutics.

Clinical Course Associated with Aseptic Meningitis Induced by Intravenous Immunoglobulin for the Treatment of Multisystem Inflammatory Syndrome in Children.

Aseptic meningitis is a rare but potentially serious complication of intravenous immunoglobulin treatment. In this case series, meningitic symptoms following intravenous immunoglobulin initiation in patients with multisystem inflammatory syndrome were rare (7/2,086 [0.3%]). However, they required the need for additional therapy and/or readmission.

Viral lumbosacral radiculitis (Elsberg syndrome) in Denmark.

PURPOSE: To describe clinical features and outcomes of viral lumbosacral radiculitis (Elsberg syndrome). METHODS: Nationwide population-based cohort study of all adults hospitalised for viral lumbosacral radiculitis at departments of infectious diseases in Denmark from 2015 to 2020. RESULTS: Twenty-eight patients with viral lumbosacral radiculitis were included (mean annual incidence: 1.2/1,000,000 adults). The median age was 35 years (IQR 27-43), and 22/28 (79%) were female. All patients had urinary retention, with 17/28 (61%) needing a catheter. On admission, at least one sign or symptom of meningitis (headache, neck stiffness, photophobia/hyperacusis) was present in 18/22 (82%). Concurrent genital herpetic lesions were present in 11/24 (46%). The median cerebrospinal fluid leukocyte count was 153 cells/µL (IQR 31-514). Magnetic resonance imaging showed radiculitis/myelitis in 5/19 (26%). The microbiological diagnosis was herpes simplex virus type 2 in 19/28 (68%), varicella-zoster virus in 2/28 (7%), and unidentified in 7/28 (25%). Aciclovir/valaciclovir was administered in 27/28 (96%). At 30 days after discharge, 3/27 (11%) had persistent urinary retention with need of catheter. At 180 days after discharge, moderate disabilities (Glasgow Outcome Scale score of 4) were observed in 5/25 (20%). CONCLUSIONS: Urinary retention resolved within weeks in most patients with viral lumbosacral radiculitis, but moderate disabilities according to the Glasgow Outcome Scale were common at the end of follow-up.

Meningitis-retention syndrome: a review and update of an unrecognized clinical condition.

OBJECTIVES: We summarized the clinical and radiological characteristics of meningitis-retention syndrome (MRS), its therapeutic options, and urological outcome, to better understand the pathogenesis of this syndrome and to evaluate the effectiveness of corticosteroids in reducing the period of urinary retention. METHODS: We reported a new case of MRS in a male adolescent. We also reviewed the previously 28 reported cases of MRS, collected from inception up to September 2022. RESULTS: MRS is characterized by aseptic meningitis and urinary retention. The mean length of the interval between the onset of the neurological signs and the urinary retention was 6.4 days. In most cases, no pathogens were isolated in cerebrospinal fluid, except for 6 cases in which Herpesviruses were detected. The urodynamic study resulted in a detrusor underactivity, with a mean period for urination recovery of 4.5 weeks, regardless of therapies. DISCUSSION: Neurophysiological studies and electromyographic examination are not pathological, distinguishing MRS from polyneuropathies. Although there are no encephalitic symptoms or signs, and the magnetic resonance is often normal, MRS may represent a mild form of acute disseminated encephalomyelitis, without radiological detectable medullary involvement, due to the prompt use of steroids. It is believed that MRS is a self-limited disease, and no evidence suggests the effectiveness of steroids, antibiotics, and antiviral treatment in its clinical course.

Urinary Retention Suggesting Aseptic Meningitis: Meningitis-Retention Syndrome Without Physical Signs of Meningeal Irritation.

Meningitis-retention syndrome (MRS) is the combination of aseptic meningitis and acute urinary retention that occurs in the absence of other neurological diseases. The cause(s) of MRS remain unclear. A 57-year-old Japanese woman was referred to our hospital for the evaluation of persistent fever and headache. The fever's cause was initially unclear, but the presence of urinary retention raised concern about possible aseptic meningitis despite no physical indications of meningeal irritation. Only typical cases of MRS have been reported thus far to our knowledge, and it is important that clinicians are aware of MRS when it presents in this atypical form.

Neuro-Leptospirosis: Experience from a tertiary center of North India.

Leptospirosis is a common zoonotic disease, especially in agricultural countries. Neurological manifestations of leptospirosis (neuroleptospirosis) have been reported in a study with a small number of patients. Here we report seven consecutive patients with neuroleptospirosis admitted to a neurology ward. All seven patients had a meningoencephalitis-like presentation. Leptospirosis was confirmed by polymerase chain reaction. None of the patients had systemic involvement. All patients responded significantly to intravenous ceftriaxone and oral doxycycline, recovering completely. Diagnosis of neuroleptospirosis should always be considered in patients with acute meningoencephalitis along with bacterial and viral encephalitis. Prognosis is good with early diagnosis and appropriate treatment.

Non-infectious meningitis and CNS demyelinating diseases: A conceptual review.

Many cases of aseptic meningitis or meningoencephalitis, unresponsive to antimicrobial treatments, have been reported recently in patients with established/new-onset central nervous system (CNS) inflammatory demyelinating diseases (CNSIDDs). Given the higher probability of infectious etiologies, CNSIDDs are rarely considered among the differentials in meningitis or meningoencephalitis cases. We gathered and tabulated cases of non-infectious, steroid-responsive meningitis or meningoencephalitis associated with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein-associated disease (MOGAD). This conceptual review highlights the need to bolster routine infectious workups with immunological workups in cases of meningoencephalitis or meningitis where potential autoimmune etiologies can be suspected. Although differentiating CNSIDDs with meningeal involvement from infectious meningitis may not substantially affect acute treatment strategies, long-term management and follow-up of the two are entirely different. We also discuss future research directions and hypotheses on how CNSIDDs may be associated with meningitis-like presentations, e.g. overlapping glial fibrillary acidic protein astrocytopathy or autoimmune encephalitis, alterations in regulatory T-helper cells function, and undetected viral agents.

Aseptic meningitis as initial manifestation of systemic lupus erythematosus: Case series.

Aseptic meningitis is a rare presentation of systemic lupus erythematosus (SLE). High index of suspicion is crucial when there is suboptimal response to the initial standard meningitis treatment and presence of connective tissue disease symptoms. We report 3 cases of aseptic meningitis as the main initial presentation of SLE. The diagnosis of SLE as the underlying cause of the aseptic meningitis was supported by the clinical, laboratory and radiological findings. All patients showed good response after treated with immunosuppressant therapy.

Immune-related aseptic meningitis and strategies to manage immune checkpoint inhibitor therapy: a systematic review.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) can induce adverse neurological effects. Due to its rarity as an adverse effect, meningitis has been poorly described. Therefore, meningitis diagnosis and management can be challenging for specialists. Moreover, meningitis can be an obstacle to resuming immunotherapy. Given the lack of alternatives, the possibility of reintroducing immunotherapy should be discussed on an individual basis. Here, we present a comprehensive systematic review of meningitis related to ICIs. REVIEW: We performed a search for articles regarding immune-related meningitis published in PubMed up to November 2021 with the MeSH terms "meningitis" and "immune checkpoint" using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. We summarized the studies not only by category but also based on whether it was a primary article or case report to provide a systematic overview of the subject. We reviewed a total of 38 studies and herein report the clinical experiences, pharmacovigilance data and group knowledge from these studies. CONCLUSION: This review summarizes the existing information on immune-related meningitis and the possibility of reintroducing immunotherapy after the development of central neurological side effects. To the best of our knowledge, there is little information in the literature to guide clinicians on decisions regarding whether immunotherapy should be continued after a neurological adverse event occurs, especially meningeal events. This review emphasizes the necessity of systematic examinations, steroid treatment (as a cornerstone of management) and the need for further exploratory studies to obtain a clearer understanding of how to better manage patients who experience these side effects. The findings summarized in this review can help provide guidance to practitioners who face this clinical situation.

Chronic aseptic meningitis caused by enterovirus in a humorally immunosuppressed adult patient presenting with sensorineural hearing loss: a case report.

BACKGROUND: Enterovirus has been described as a cause of aseptic meningitis in humorally immunosuppressed patients. CASE PRESENTATION: A 67-year-old female with a history of mantle cell lymphoma on rituximab therapy presented with subacute hepatitis, myalgias, and sensorineural hearing loss several months after an initial febrile illness. She was diagnosed with enterovirus infection by CSF PCR as a unifying etiology of her presentation, representing an unusual presentation of disease. DISCUSSION AND CONCLUSIONS: This patient's unique presentation and clinical course presents important implications in the care of similarly immunosuppressed patients with cryptic complaints.

Aseptic meningitis following AZD1222 COVID-19 vaccination.

The AZD1222 is one of the vaccines used against coronavirus disease 2019 (COVID-19), which is currently being used in many countries worldwide. Some important neurological side effects have been reported in association with this vaccine, but aseptic meningitis has not yet been reported. Herein, we report a case of aseptic meningitis in a 26-year-old health care worker, following the first dose of the AZD1222 vaccine.

The epidemiology of aseptic meningitis in New Zealand children from 1991 to 2020.

AIM: Aseptic meningitis, including culture negative and viral meningitis, contributes a significant health-care burden, including unnecessary antibiotic use and hospitalisation to treat possible bacterial meningitis. This study analysed aseptic meningitis hospitalisations in New Zealand (NZ) children over 29 years. METHODS: In this population-based study, aseptic meningitis hospitalisations in NZ children <15 years old were analysed from 1991 to 2020. Incident rate ratios were calculated using Poisson regression models. Variations in hospitalisations by age, year, sex, ethnicity, geographical region and socio-economic deprivation were analysed. RESULTS: There were 5142 paediatric aseptic meningitis hospitalisations from 1991 to 2020. Most were unspecified viral meningitis (64%), followed by enterovirus (29%). Hospitalisation rates varied annually with a median of 18.4/100 000 children including a peak in 2001 of 56.4/100 000 (51.7-61.6). From 2002 to 2019, rates increased by 8.4%/year (7.2-9.5%) in infants <90 days old but decreased in all other age groups. In 2020, a reduction in hospitalisations to 9.6/100 000 (7.9-11.8) occurred, and in infants <90 days old were 0.37 times expected. Hospitalisations were 1.50 times (1.49-1.68) higher in males than females; higher in children of Maori (P < 0.001) and Pacific (P < 0.001) versus European ethnicity; and higher for children living in the most (2.44 times, (2.16-2.75)) versus least deprived households; and in northern versus southern NZ. CONCLUSIONS: Aseptic meningitis hospitalisations increased in young infants during 29 years of surveillance, apart from 2020 when admissions reduced during the COVID-19 pandemic. In contrast, hospitalisations decreased in children aged >1 year. Further investigation into reasons for higher admissions by ethnic group, geographical location and increased deprivation are required.