Factors influencing PCR detection of viruses in cerebrospinal fluid of patients with suspected CNS infections

Comparison of two assays to diagnose herpes simplex virus in patients with central nervous system infections

BACKGROUND

Multiplex PCR panels are frequently used for detecting the diagnosis of central nervous system infection, but have demonstrated lower sensitivity for herpes simplex virus (HSV) compared to targeted PCRs. Providers in our institution frequently order both multiplex (BioFire Meningitis/Encephalitis Panel (MEP)) and targeted HSV PCR (Diasorin Simplexa HSV-1/2 Direct), allowing comparison of assay performance in practice and a unique clinical characterization of patients with concordant positive or discordant results.

METHODS

We retrospectively analyzed all HSV testing performed using the two assays simultaneously in a large multi-center institution between 12/10/2018 and 6/6/2022. We described and compared laboratory, diagnostic and therapeutic data between patients with positive results on both assays with patients with discordant results.

RESULTS

1,387 patients were tested with both assays, of which 25 were positive on at least one assay. Eleven (44%) had discordant results; 9 were targeted-PCR-positive/MEP-negative and 2 were targeted-PCR-negative/MEP-positive. Compared with patients with concordant positive results, discordant targeted PCR-positive/MEP-negative patients had a higher PCR cycle threshold value (i.e., >35) and milder illness characterized by lower CSF WBC counts (4 vs 152; p = 0.032), fewer MRI abnormalities (37.5% vs. 87.5%; p = 0.039), HSV meningoencephalitis as primary discharge diagnosis (33% vs. 100%; p<0.0001) and were more often treated with oral medication or none at all.

CONCLUSIONS

Patients with discordant targeted PCR-positive/MEP-negative results represent a population with milder clinical disease. These findings will help clinicians and laboratorians determine when both targeted HSV and multiplex assays should be performed simultaneously and identify patients for whom a multiplex PCR may suffice, despite lower assay sensitivity.

Viral-induced neuroinflammation: Different mechanisms converging to similar exacerbated glial responses

There is increasing evidence that viral infections are the source/origin of various types of encephalitis, encephalomyelitis, and other neurological and cognitive disorders. While the involvement of certain viruses, such as the Nipah virus and measles virus, is known, the mechanisms of neural invasion and the factors that trigger intense immune reactions are not fully understood. Based on recent publications, this review discusses the role of the immune response, interactions between viruses and glial cells, and cytokine mediators in the development of inflammatory diseases in the central nervous system. It also highlights the significant gaps in knowledge regarding these mechanisms.

Chronic liver disease and hepatic encephalopathy patients with new-onset focal motor status epilepticus: Indicates herpetic encephalitis

Seizures are not common in cases with chronic liver disease. Overall seizures have been reported in 20-30% of cases in chronic liver disease associated with hepatic encephalopathy. We report two cases of chronic liver disease patients who presented with new-onset refractory focal status epilepticus (SE). Both patients had encephalitis and seizures which responded only when acyclovir was added to the treatment with antiepileptic medication. Herpes encephalitis should be considered as a possible diagnosis in new-onset focal seizures or focal SE in patients with chronic liver disease with or without hepatic encephalopathy, pending further investigations.

Clinical Metagenomic Next-Generation Sequencing for Diagnosis of Secondary Glaucoma in Patients With Cytomegalovirus-Induced Corneal Endotheliitis

Glaucoma is the second leading cause of blindness globally. Growing scientific evidence indicated that inflammation of the trabecular meshwork induced by corneal endotheliitis could lead to secondary glaucoma. Cytomegalovirus (CMV) has been identified as the most common herpes virus in corneal endotheliitis patients. Early detection is critical in preventing endothelial cell loss, and patient management should vary based on different pathological factors. However, routine culture and real-time polymerase chain reaction (qPCR) have difficult in distinguishing whether CMV, Varicella Zoster Virus (VZV) or Herpes Simplex Virus (HSV) causes endothiliitis. This may result in inappropriate treatment, which may prolong or aggravate the status of disease. We compared the sensitivity and specificity of qPCR and Metagenomic Next-Generation Sequencing (mNGS) in the aqueous humor of patients with suspected CMV endotheliitis in this study. Our results showed that four out of 11 (36.4%) of our patients were positive for CMV by qPCR, whereas mNGS had a 100% detection rate of CMV. Our findings implied that mNGS could be a useful diagnostic tool for CMV-induced endotheliitis.

Acute Presentation of Newly Diagnosed Multiple Sclerosis Associated With Polymerase Chain Reaction-Proven Human Herpesvirus 6 Central Nervous System Infection

We present the case of a 26-year-old male who was found to have human herpesvirus 6 (HHV-6) in his cerebrospinal fluid (CSF) during acute presentation of multiple sclerosis (MS). Paresthesia of the lower extremities was his only symptom during the initial presentation, and workup for MS was not included during this evaluation. A single dose of IV steroids failed to improve his condition, and symptoms became more severe. Upon secondary evaluation, MRI revealed white-matter disease with plaques at multiple levels of the cervical spine and central nervous system (CNS). Lumbar puncture was obtained, and CSF analysis was positive for HHV-6 DNA. After five days of oral steroid treatment and physical therapy for three weeks, his symptoms continued to worsen. MRI at this time demonstrated an increase in the size of previous plaques and new foci of white matter disease. Repeat CSF analysis was negative for HHV-6. The virus’ association with relapse of MS has been investigated by many studies. However, there is a lack of literature investigating its role in causing MS disease. In this case report, we highlight the need for further research aimed at determining if HHV-6 is an environmental trigger for MS disease onset.

Diagnostic approach and treatment regimens in adult patients suffering from antibody-mediated or paraneoplastic encephalitis

Identification of patients with antibody-mediated encephalitis poses a diagnostic challenge and any delay in that respect will increase the interval until initiation of immunotherapy and may negatively affect the patient´s clinical outcome. Within this review we focus on therapeutic strategies in antibody-mediated encephalitis and propose how to proceed with patients, who are suspected to have encephalitis of unknown origin. We further briefly outline differences in treatment of paraneoplastic and antibody-mediated encephalitis according to its pathomechanisms.

Elsberg syndrome following acute immunosuppressive treatment for multiple sclerosis relapse

First described more than 80 years ago, Elsberg Syndrome (ES) continues to be an under-recognized cause of cauda equina syndrome (CES). ES is an infectious disorder that presents with lower thoracic and/or lumbosacral myelitis in conjunction with CES, and most often occurs in the setting of herpes simplex virus 2 (HSV-2) reactivation (Savoldi et al., 2017; Eberhardt et al., 2004; Whalen et al., 2019). Comorbid neurologic diseases like multiple sclerosis (MS) can become a detrimental confounding factor leading to delayed diagnosis and management of ES due to pre-existing diagnostic bias. We present a case of relapsing-remitting MS (RRMS) complicated by ES, likely due to reactivation of a latent HSV infection following high immunosuppression for presumed refractory MS relapses.

Using the Acute Flaccid Paralysis Surveillance System to Identify Cases of Acute Flaccid Myelitis, Australia, 2000‒2018

Since 2012, the United States has reported a distinct syndrome of acute flaccid paralysis (AFP) with anterior myelitis, predominantly in children. This polio-like syndrome was termed acute flaccid myelitis (AFM). Australia routinely conducts AFP surveillance to exclude poliomyelitis. We reviewed 915 AFP cases in Australia for children <15 years of age during 2000‒2018 and reclassified a subset to AFM by using the US Council of State and Territorial Epidemiologists case definition. We confirmed 37 AFM cases by using magnetic resonance imaging findings and 4 probable AFM cases on the basis of cerebrospinal fluid pleocytosis. Nonpolio enteroviruses were detected in 33% of AFM cases from which stool samples were tested. Average annual AFM incidence was 0.07 cases/100,000 person-years in children <15 years of age. AFM occurred sporadically in Australia before 2010 but regularly since then, indicating sustained, albeit rare, clinical manifestation in children. The AFP surveillance system in Australia is well-positioned to identify future AFM cases.

Detection and genome characterization of Middelburg virus strains isolated from CSF and whole blood samples of humans with neurological manifestations in South Africa

BACKGROUND

The Old world Alphavirus, Middelburg virus (MIDV), is not well known and although a few cases associated with animal illness have previously been described from Southern Africa, there has been no investigation into the association of the virus with human illness. The current study aimed to investigate possible association of MIDV infection with febrile or neurological manifestations in hospitalized or symptomatic patients fromGauteng, South Africa.

METHODS

This study is a descriptive retrospective and prospective laboratory based study. Archived cerebrospinal fluid (CSF) samples submitted to the National Health Laboratory Service (NHLS), Tshwane Academic division for viral investigation from public sector hospitals in Gauteng as well as EDTA (ethylenediaminetetraacetic acid) whole blood samples from ad hoc cases of veterinary students, presenting with neurological and febrile illness, were selected and screened for the presence of alphaviruses using real-time reverse transcription(rtRT) PCR.Virus isolations from rtRT-PCR positive samples were conducted in Vero cell culture and used to obtain full genome sequences. Basic descriptive statistical analysis was conducted using EpiInfo.

RESULTS

MIDV was detected by rtRT-PCR in 3/187 retrospective CSF specimens obtained from the NHLS from hospitalised patients in the Tshwane region of Gauteng and 1/2 EDTA samples submitted in the same year (2017) from ad hoc query arbovirus cases from veterinary students from the Faculty of Veterinary Science University of Pretoria.Full genome sequences were obtained for virus isolates from two cases; one from an EDTA whole blood sample (ad hoc case) and another from a CSF sample (NHLS sample).Two of the four Middelburg virus positive cases,for which clinical information was available, had other comorbidities or infections at the time of infection.

CONCLUSION

Detection of MIDV in CSF of patients with neurological manifestations suggests that the virus should be investigated as a human pathogen with the potential of causing or contributing to neurological signs in children and adults.

Guillain-Barré Syndrome in the COVID-19 Pandemic

There have been several reported cases of severe acute respiratory syndrome (SARS-CoV-2) infection that were associated with an increased incidence of neurological manifestations, including Guillain–Barré syndrome (GBS). This review aims to present information on the reports of GBS associated with coronavirus disease 2019 (COVID-19) infection. Our review is retrospective work examining articles published from the 1 April 2020 to the 8 May 2021 in the English language. We used the diagnostic criteria and classification published by the National Institute of Neurological Disorders and Stroke and Brighton Collaboration. GBS is usually a postinfectious syndrome, but GBS in the COVID-19 pandemic also takes on a para-infectious profile. In the reports, the genetic factor has a role in developing GBS in some patients. In conclusion, the association between COVID-19 and GBS is not very clear. Still, one mechanism is strongly associated with COVID-19 and immune-mediated neurological complications, which is molecular mimicry between SARS-CoV-2 and human autoantigens.

Clinical Reasoning: A 57-Year-Old Man With Stepwise Progressive Paraparesis, Sensory Loss, Urinary Retention, and Constipation

We present the case of a 57-year-old man with protein S deficiency and left leg deep vein thrombosis (DVT) five years prior, who developed stepwise progressive bilateral lower limb weakness, numbness/paresthesia, gait imbalance, hesitancy of micturition, and constipation in the setting of recurrent left common femoral DVT treated with apixaban. Symptoms amplified with Valsalva, corticosteroids, and post-lumbar puncture, with longitudinally extensive mid-thoracic T2-hyperintense lesion extending to the conus associated with hazy holocord enhancement on magnetic resonance imaging (MRI), raising suspicion for spinal dural arteriovenous fistula (sDAVF). Initial digital subtraction angiography (DSA) was negative for sDAVF. However, cerebral spinal fluid (CSF) was herpes simplex virus (HSV)-2 positive, and he was treated with antiviral therapy. Unfortunately, he continued to worsen despite treatment. Repeat neuroimaging twelve months after initial presentation demonstrated persistent lower thoracic/conus lesion in addition to cauda equina enhancement and subtle dorsal T2-hypointense flow voids. We raised red flags (eg, lack of clinical prodrome, no herpetic rash, no CSF pleocytosis, and rostral extent of the lesion) that suggested the HSV2 nucleic acid detection was perhaps unrelated to the neurological syndrome. Given the high index of suspicion for sDAVF, we repeated spinal vascular imaging. Spinal MRA demonstrated dilated right dorsal perimedullary veins from T10 to T11. Repeat DSA revealed a right T10 sDAVF. Microsurgical treatment rather than embolization of the fistula was successful without complication, with significant improvement in motor, sphincter, and to a lesser extent sensory function, with residual gait imbalance after inpatient rehabilitation three weeks postoperatively.

Evaluation of the selection of cerebrospinal fluid testing in suspected meningitis and encephalitis

Diagnostic stewardship interventions can decrease unnecessary antimicrobial therapy and microbiology laboratory resources and costs. This retrospective cross-sectional study evaluated factors associated with inappropriate initial cerebrospinal fluid (CSF) testing in patients with suspected community-acquired meningitis or encephalitis. In 250 patients, 202 (80.8%) and 48 (19.2%) were suspected meningitis and encephalitis, respectively. 207 (82.8%) patients had inappropriate and 43 (17.2%) appropriate testing. Any inappropriate CSF test was greatest in the immunocompromised (IC) group (n = 54, 91.5%), followed by non-IC (n = 109, 80.1%) and HIV (n = 44, 80%). Ordering performed on the general ward was associated with inappropriate CSF test orders (adjOR 2.81, 95% CI [1.08-7.34]). Laboratory fee costs associated with excessive testing was close to $300,000 per year. A stepwise algorithm defining empiric and add on tests according to CSF parameters and patient characteristics could improve CSF test ordering in patients with suspected meningitis or encephalitis.

Detection of Major Human Herpesviruses in Iranian Patients with Suspected Encephalitis Using Multiplex Polymerase Chain Reaction

BACKGROUND

The Herpesviridae family plays a significant etiological role in central nervous system viral infections during primary infection or reactivation from a latent form. Early detection is crucial because prescribing some antivirals can prevent severe side effects or life-threatening conditions.

METHODS

In this study, 251 CSF specimens were collected from patients with clinical suspicion of viral encephalitis in Pars Hospital, Tehran, Iran. DNA was extracted, and a multiplex PCR was designed to investigate the presence of herpes simplex virus-1, herpes simplex virus-2, varicella zoster virus, Epstein-Barr virus, and cytomegalovirus.

RESULTS

Overall, 59 cases of the 251 CSF samples were positive for multiplex PCR (23.5%). The most frequent positive findings were EBV and HSV, with a prevalence of 10.3% and 8.7% (5.5% HSV-1 and 3.1% HSV-2), respectively. Four co-infections were also seen in this study.

CONCLUSIONS

This multiplex PCR assay detects simultaneously different herpesviruses in CSF samples of patients with suspected encephalitis in 2 rounds of PCR amplification; therefore, it is a reliable and cost-saving diagnostic method for evaluating patients infected with herpesvirus with neurological disorders.

Cerebrospinal fluid in COVID-19: A systematic review of the literature

OBJECTIVE

We sought to review the literature on cerebrospinal fluid (CSF) testing in patients with COVID-19 for evidence of viral neuroinvasion by SARS-CoV-2.

METHODS

We performed a systematic review of Medline and Embase between December 1, 2019 and November 18, 2020 to identify case reports or series of patients who had COVID-19 diagnosed based on positive SARS-CoV-2 polymerase chain reaction (PCR) or serologic testing and had CSF testing due to a neurologic symptom.

RESULTS

We identified 242 relevant documents which included 430 patients with COVID-19 who had acute neurological symptoms prompting CSF testing. Of those, 321 (75%) patients had symptoms that localized to the central nervous system (CNS). Of 304 patients whose CSF was tested for SARS-CoV-2 PCR, there were 17 (6%) whose test was positive, all of whom had symptoms that localized to the central nervous system (CNS). The majority (13/17, 76%) of these patients were admitted to the hospital because of neurological symptoms. Of 58 patients whose CSF was tested for SARS-CoV-2 antibody, 7 (12%) had positive antibodies with evidence of intrathecal synthesis, all of whom had symptoms that localized to the CNS. Of 132 patients who had oligoclonal bands evaluated, 3 (2%) had evidence of intrathecal antibody synthesis. Of 77 patients tested for autoimmune antibodies in the CSF, 4 (5%) had positive findings.

CONCLUSION

Detection of SARS-CoV-2 in CSF via PCR or evaluation for intrathecal antibody synthesis appears to be rare. Most neurological complications associated with SARS- CoV-2 are unlikely to be related to direct viral neuroinvasion.

Infectious Myelopathies

PURPOSE OF REVIEW

This article reviews infectious etiologies of spinal cord dysfunction, emphasizing the importance of recognizing common clinicoradiographic syndromes and interpreting them in the context of exposure risk and individual host susceptibilities.

RECENT FINDINGS

This article discusses the shifting spectrum of neurologic infectious diseases, the growing population of patients who are immunocompromised, and the emergence of effective antiretroviral therapies. In addition, it discusses new molecular and serologic tests that have the potential to enhance our ability to rapidly and accurately diagnose infectious diseases of the spine.

SUMMARY

When evaluating patients with suspected infectious myelopathies, it is imperative to narrow the range of pathogens under consideration. The geography, seasonality, and clinicoradiographic presentation and immunocompetence status of the patient define the range of potential pathogens and should guide testing and initial management.

The Prevalence of Viruses in the Cerebrospinal Fluid of Children with Aseptic Meningitis in Shiraz, Iran

Objectives: The current study aimed to evaluate the causative agents of viral meningitis through real-time PCR among children with aseptic meningitis. Methods: Children aged 1 month to 16 years with suspected viral meningitis were enrolled in this study (March 2014-February 2015). Cerebrospinal fluid samples were analyzed by real-time PCR for detection of enterovirus, mumps, measles, adenovirus, EBV, CMV, VZV, hhv 6, and rubella viruses. Demographic information, laboratory data, and clinical presentations of patients were also collected. Results: Of 56 patients suspected to viral meningitis, 21 (38.9 %) had a positive PCR result. Enterovirus (42.85%) and mumps (38.1%) were the most prevalent viruses, and VZV and measles were not detected. Three children were coinfected with enterovirus/hhv6, enterovirus/EBV, and mump/adenovirus. Fever, headache, and nausea/vomiting were the most common symptoms in children. The rates of symptoms were not statistically significant among children with positive and negative PCR tests. Conclusions: In the present study Enterovirus and mumps viruses were the most common causes of viral meningitis in children. PCR, as a rapid test for the diagnosis of viral meningitis, can be used to decrease hospitalization length.

Neurolisteriosis in a previously asymptomatic patient with serum IgM deficiency: a case report

BACKGROUND

Listeria monocytogenes is an opportunistic pathogen of the central nervous system commonly associated with impaired cell-mediated immunity. We hereby present a case of adult neurolisteriosis where the only immunological feature persistently present was serum IgM deficiency, suggesting that non-specific humoral immunity may also play a central role in the control of neuroinvasion by Listeria monocytogenes.

CASE PRESENTATION

A 62-year-old male who had never experienced severe infections presented with headache, nuchal rigidity and confusion. Neuroimaging was normal and lumbar puncture revealed pleiocytosis (760 leukocytes/mm3) and hypoglycorrhachia (34 mg/dL). The patient was treated empirically for bacterial meningitis. Indeed, further analysis of the CSF showed infection by Listeria monocytogenes, which was accompanied by reduced serum IgM levels that persisted well beyond the period of acute bacterial infection. Levels of IgG and IgA isotypes, along with peripheral blood counts of major leukocyte subsets, were at the same time largely preserved. Intriguingly, the absence of membrane-bound IgM on B cells was essentially complete in the acute post-infection period leading to a remarkable recovery after 12 months, suggesting that mechanisms other than defective membrane expression are underlying serum deficiency.

CONCLUSIONS

As far as we know, this is the first reported case of neurolisteriosis associated with IgM deficiency in an adult individual without a history of severe infections or other underlying conditions. A possible role of circulating IgM against invasive disease caused by Listeria monocytogenes, particularly in the early course of host-pathogen interaction, is discussed.

Understanding Enterovirus D68-Induced Neurologic Disease: A Basic Science Review

In 2014, the United States (US) experienced an unprecedented epidemic of enterovirus D68 (EV-D68)-induced respiratory disease that was temporally associated with the emergence of acute flaccid myelitis (AFM), a paralytic disease occurring predominantly in children, that has a striking resemblance to poliomyelitis. Although a definitive causal link between EV-D68 infection and AFM has not been unequivocally established, rapidly accumulating clinical, immunological, and epidemiological evidence points to EV-D68 as the major causative agent of recent seasonal childhood AFM outbreaks in the US. This review summarizes evidence, gained from in vivo and in vitro models of EV-D68-induced disease, which demonstrates that contemporary EV-D68 strains isolated during and since the 2014 outbreak differ from historical EV-D68 in several factors influencing neurovirulence, including their genomic sequence, their receptor utilization, their ability to infect neurons, and their neuropathogenicity in mice. These findings provide biological plausibility that EV-D68 is a causal agent of AFM and provide important experimental models for studies of pathogenesis and treatment that are likely to be difficult or impossible in humans.

Human Pegivirus in Patients with Encephalitis of Unclear Etiology, Poland

Sequence analysis of human pegivirus from 3 patients indicates that the central nervous system constitutes a separate viral compartment from serum.

Human pegivirus (HPgV), previously called hepatitis G virus or GB virus C, is a lymphotropic virus with undefined pathology. Because many viruses from the family Flaviviridae, to which HPgV belongs, are neurotropic, we studied whether HPgV could infect the central nervous system. We tested serum and cerebrospinal fluid samples from 96 patients with a diagnosis of encephalitis for a variety of pathogens by molecular methods and serology; we also tested for autoantibodies against neuronal antigens. We found HPgV in serum and cerebrospinal fluid from 3 patients who had encephalitis of unclear origin; that is, all the markers that had been tested were negative. Single-strand confirmation polymorphism and next-generation sequencing analysis revealed differences between the serum and cerebrospinal fluid–derived viral sequences, which is compatible with the presence of a separate HPgV compartment in the central nervous system. It is unclear whether HPgV was directly responsible for encephalitis in these patients.

High-dose corticosteroids for acute cytomegalovirus-associated transverse myelitis in the immunocompetent patient: a case report and systematic review

We present an immunocompetent patient with transverse myelitis (TM) during acute cytomegalovirus (CMV) infection, as evidenced by a reactive serum CMV IgM and CMV viremia. The patient had an excellent outcome after receiving only high-dose methylprednisolone. Given concerns that practitioners may have around the use of immunosuppressive therapy for this potentially infectious myelopathy, we systematically reviewed the literature to assess outcomes after administration of high-dose corticosteroids to this population. Despite severe disease at clinical nadir with inability to ambulate, immunocompetent patients with acute CMV-associated TM who received high-dose corticosteroids had good clinical outcomes 1 month to 1 year after presentation.

Progressive idiopathic unilateral corneal endothelial failure of unknown aetiology in phakic eyes

AIM

To describe a cohort of patients with irreversible unilateral bullous keratopathy (BK) of undetermined aetiology.

METHOD

Retrospective, single-centre case series in a tertiary corneal referral centre.

RESULTS

Eleven consecutive patients (nine females; mean age 71.7 years) presented from 1999 to 2009 with acute onset unilateral visual loss. At presentation, the best-corrected visual acuity of the affected eyes was 6/9 or worse with mean central corneal thickness (CCT) of 684 (SD 66) μm. Specular microscopy was not possible in the affected eyes. There was no other ocular pathology in the affected eye. The fellow eye remained normal throughout the study (mean endothelial cell density (ECD) of 1980 (SD 736) cells/mm² and CCT of 536 (SD 34) μm). Topical steroid, antiviral treatments (both topical and systemic) or a combination of both did not yield any improvement. After a mean follow-up of 82.2 months, eight eyes had penetrating keratoplasty (PK). One required two regrafts. Histology showed typical BK features, with endothelial cell (EC) loss and thickened Descemet's membrane (DM). Transmission electron microscopy revealed DM abnormalities in a non-consistent pattern, featuring variable collagen deposition posterior to the non-banded zone. The ECs were degenerated, reduced or absent. Neither viruses nor pseudoexfoliation material was identified.

CONCLUSION

While medical treatment is not beneficial, PK appears to offer good results. Non-guttate Fuchs' corneal endothelial dystrophy merits consideration but it would be unusual to see an exclusively unilateral presentation. DM thickening is reflective of a chronic EC loss but the cause of this loss remains elusive.

Epidemiological surveillance of herpes viral encephalitis in Cordoba, Colombia

Objective To establish an epidemiological surveillance of viral herpes encephalitis in major hospitals of Monteria, Cordoba. Methods From September 2009 to December 2011, a descriptive study of cases of viral encephalitis was made in three hospitals in the city of Monteria. Cerebrospinal fluid (CSF) samples from 118 patients were included in the study. Clinical aspects, as well as cytochemical and microbiological analysis (Gram stain and culture) of CSF, were used for selecting the patients. Virus detection was performed by using multiplex nested PCR for Herpes simplex virus 1 and 2, Epstein Barr virus, Cytomegalovirus and Varicella zoster virus. Results Viral DNA of herpesvirus was detected in the CSFs of 30 (25.4 %) participants, as follows: 22 (18.6 %) Herpes simplex 1 and 2 viruses, 4 (3.3 %) Cytomegalovirus and 1 (0.8 %) Varicella zoster virus. Co-infections were observed in 3 patients (2.5 %), 1 case by HSV-VZV and 2 cases by CMV/HSV. The clinical manifestations of the patients included: headache (18.6 %), fever (14.4 %), asthenia (10.1 %), seizures (9.3 %), vomiting (8.4 %), and stiff neck (5.9 %). Thirty percent of the patients also had HIV-AIDS. A case fatality rate of 20 % was observed for the patients. Conclusions This paper shows that herpesvirus is a cause of infection of the CNS in patients from Cordoba. This study contributes to the epidemiology of encephalitis, as well as to patient management.

Case report: subacute tetraplegia in an immunocompromised patient

Background

Clinical reasoning in Neurology is based on general associations which help to deduce the site of the lesion. However, even “golden principles” may occasionally be deceptive. Here, we describe the case of subacute flaccid tetraparesis due to motor cortical lesions. To our knowledge, this is the first report to include an impressive illustration of nearly symmetric motor cortical involvement of encephalitis on brain MRI.

Case presentation

A 51 year old immunocompromized man developed a high-grade pure motor flaccid tetraparesis over few days. Based on clinical presentation, critical illness polyneuromyopathy was suspected. However, brain MRI revealed symmetrical hyperintensities strictly limited to the subcortical precentral gyrus. An encephalitis, possibly due to CMV infection, turned out to be the most likely cause.

Conclusion

While recognition of basic clinical patterns is indispensable in neurological reasoning, awareness of central conditions mimicking peripheral nervous disease may be crucial to detect unsuspected, potentially treatable conditions.

CTLA-4-expression on VZV-specific T cells in CSF and blood is specifically increased in patients with VZV related central nervous system infections

VZV-reactivation may lead to symptomatic central nervous system (CNS) diseases, but identification of VZV as causative pathogen of CNS-diseases is challenging. This study was performed to characterize VZV-specific T cells from cerebrospinal fluid (CSF) and blood of patients with active CNS-disease and to determine whether this may improve differential diagnosis. 27 patients with pleocytosis in the CSF were recruited and classified into three groups (10 VZV-related, 10 non-VZV-related, 7 unclear). VZV-specific CD4⁺ T cells were quantified in CSF and blood after simultaneous stimulation with a VZV-antigen lysate and detection of cytokines (IFN-γ, IL-2, TNF-α) and CTLA-4. Polyclonal stimulation served as positive control. VZV-specific CD4⁺ T-cell frequencies were highest in both CSF (p = 0.0001) and blood (p = 0.011) of patients with VZV-infection, and were enriched at the site of infection (p = 0.002). While cytokine-expression profiles only showed minor differences between the groups, CTLA-4-expression levels on VZV-specific T cells from CSF and blood were significantly increased in VZV-related CNS-infections (p = 0.0002 and p<0.0001) and clearly identified VZV-related CNS-diseases (100% sensitivity and 100% specificity). Polyclonally stimulated T cells did not show any quantitative and phenotypical differences between the groups. Increased frequency and CTLA-4-expression of VZV-specific T cells from CSF or blood are specifically found in patients with VZV-related CNS-infection.

HSV-1 Encephalitis: High Index of Clinical Suspicion, Prompt Diagnosis, and Early Therapeutic Intervention Are the Triptych of Success-Report of Two Cases and Comprehensive Review of the Literature

Herpes Simplex Virus (HSV) encephalitis is an acute infectious disease of the Central Nervous System (CNS), usually affecting the limbic structures, the median temporal cortex, and the orbitofrontal regions. Its annual incidence has significantly increased over the last 20 years and the mortality rate is 7%, if early diagnosed and treated, and 70%, if left untreated, while it is associated with high rates of morbidity. It should be noted that even when Cerebrospinal fluid (CSF) analysis seems normal, imaging studies are not specific and HSV Polymerase Chain Reaction (PCR) test is negative; the clinician should be more aggressive, if clinical presentation is indicative for HSV encephalitis, by administrating acyclovir early after patient's admission. The latter may be a vital intervention for the patient, modifying the patient's clinical course. Through the presentation of two cases of HSV-1 encephalitis that we managed in our department over the last 1 year and after systematic and comprehensive research of the relevant literature, we aim at showing the crucial role of medical history and physical examination, along with the high index of clinical suspicion, in order to make promptly the diagnosis and administer timely intravenous acyclovir, limiting the possibility of complications during the disease's course.

Red blood cells in cerebrospinal fluid as possible inhibitory factor for enterovirus RT-PCR

The presence of hemoglobin in samples are considered an important inhibitory factor for polymerase chain reaction (PCR). The aim of this study was to examine the influence of red blood cells (RBC)s in cerebrospinal fluid (CSF) as an inhibitory factor to reverse transcription polymerase chain reaction (RT-PCR) for enteroviruses (EV). Forty-four CSF samples from patients showing characteristics of viral meningitis were assessed for EV by RT-PCR. Viral RNA extracted with guanidine isothyocianate buffer and virus detection was performed by in-house nested PCR. Positivity for EV RT-PCR was higher in CSF samples without RBCs than in samples with RBCs: 13(26%) and 36(9.2%), p = 0.001. In the group with positive EV RT-PCR, the mean + SD CSF RBC was 37 ± 183 cell/mm3; the group with negative results had 580 + 2,890 cell/mm3 (p = 0.007). The acceptable upper limit for CSF RBCs that could not influence RT-PCR was 108 cells/mm3. CSF samples with negative results for EV RT-PCR have more erythrocytes.

Viral etiologies in adult patients with encephalitis in Poland: A prospective single center study

Encephalitis is a severe neurological syndrome associated with high morbidity and mortality as well as long-term neurological sequelae. Despite being an important public health problem, very few extensive population-based studies were conducted so far in the world and none in Central Europe. Altogether 114 consecutive patients meeting the initial criteria for encephalitis were enrolled at the Warsaw Hospital for Infectious Diseases between June 2012 and July 2015. Eighteen patients were secondarily excluded from the analysis due to incomplete data or noinfectious cause. Potential pathogen sequences were searched for by molecular methods in the cerebrospinal fluid (CSF) and specific antibodies were detected in CSF and sera. An infectious agent was identified in 41 patients (42.7%). The most frequently diagnosed infections were Human herpesvirus 1 (HHV-1) (22 cases, 24%) followed by Enterovirus (6 cases, 6.3%), Varicella zoster virus (VZV) (5 cases, 5.2%), Tick-borne encephalitis virus (TBEV) (6 cases, 6.3%) and Cytomegalovirus (CMV) (2 cases, 2.1%). There were no cases of human adenovirus, Human herpesvirus 6 (HHV-6) or West Nile virus (WNV) infection identified. In 55 cases (57.3%) the cause of encephalitis remained unknown. Compared to patients in whom the diagnosis was determined the latter group contained more women, was less likely to manifest fever and had lower CSF pleocytosis (p < 0.05) In summary, we identified HHV-1 followed by Enterovirus, VZV and TBEV as the most common causes of encephalitis among adult patients in Poland. In a large proportion of patients the cause of encephalitis remained unknown.

Elsberg syndrome: A rarely recognized cause of cauda equina syndrome and lower thoracic myelitis

Objective:

Elsberg syndrome (ES) is an established but often unrecognized cause of acute lumbosacral radiculitis with myelitis related to recent herpes virus infection. We defined ES, determined its frequency in patients with cauda equina syndrome (CES) with myelitis, and evaluated its clinical, radiologic, and microbiologic features and outcomes.

Methods:

We searched the Mayo Clinic medical records for ES and subsequently for combinations of index terms to identify patients with suspected CES and myelitis.

Results:

Our search yielded 30 patients, 2 diagnosed with ES and an additional 28 with clinical or radiologic evidence of CES retrospectively suspected of having ES. We classified patients in 5 groups according to diagnostic certainty. MRI and EMG confirmed that 2 had only myelitis, 5 only radiculitis, and 16 both. Two had preceding sacral herpes infection and 1 oral herpes simplex. Spinal cord lesions were commonly multiple, discontinuous, not expansile, and centrally or ventrally positioned. Lesions generally spared the distal conus. Nerve root enhancement was occasionally prominent and was smooth rather than nodular. Lymphocytic CSF pleocytosis was common. Thirteen patients (43%) had viral isolation studies, which were commonly delayed; the delay may have accounted for the low rate of viral detection. Acyclovir was administered to 6 patients. Most patients recovered with sequelae; 1 patient experienced encephalomyelitis and died.

Conclusion:

ES is a definable condition likely responsible for 10% of patients with combined CES and myelitis. Radiologic findings are not entirely specific but may help in differentiating ES from some competing diagnostic considerations. We propose criteria to facilitate diagnosis.

Infectious encephalitis: utility of a rational approach to aetiological diagnosis in daily clinical practice

In this study we attempt to assess the utility of a simplified step-wise diagnostic algorithm to determinate the aetiology of encephalitis in daily clinical practice and to describe the main causes in our setting. This was a prospective cohort study of all consecutive cases of encephalitis in adult patients diagnosed between January 2010 and March 2015 at the University Hospital Vall d'Hebron in Barcelona, Spain. The aetiological study was carried out following the proposed step-wise algorithm. The proportion of aetiological diagnoses achieved in each step was analysed. Data from 97 patients with encephalitis were assessed. Following a simplified step-wise algorithm, a definite diagnosis was made in the first step in 53 patients (55 %) and in 12 additional cases (12 %) in the second step. Overall, a definite or probable aetiological diagnosis was achieved in 78 % of the cases. Herpes virus, L. monocytogenes and M. tuberculosis were the leading causative agents demonstrated, whereas less frequent aetiologies were observed, mainly in immunosuppressed patients. The overall related mortality was 13.4 %. According to our experience, the leading and treatable causes of encephalitis can be identified in a first diagnostic step with limited microbiological studies. L. monocytogenes treatment should be considered on arrival in some patients. Additional diagnostic effort should be made in immunosuppressed patients.

Neuroimaging in encephalitis: analysis of imaging findings and interobserver agreement

Aim

To assess the role of imaging in the early management of encephalitis and the agreement on findings in a well-defined cohort of suspected encephalitis cases enrolled in the Prospective Aetiological Study of Encephalitis conducted by the Health Protection Agency (now incorporated into Public Health England).

Materials and methods

Eighty-five CT examinations from 68 patients and 101 MRI examinations from 80 patients with suspected encephalitis were independently rated by three neuroradiologists blinded to patient and clinical details. The level of agreement on the interpretation of images was measured using the kappa statistic. The sensitivity, specificity, and negative and positive predictive values of CT and MRI for herpes simplex virus (HSV) encephalitis and acute disseminated encephalomyelitis (ADEM) were estimated.

Results

The kappa value for interobserver agreement on rating the scans as normal or abnormal was good (0.65) for CT and moderate (0.59) for MRI. Agreement for HSV encephalitis was very good for CT (0.87) and MRI (0.82), but only fair for ADEM (0.32 CT; 0.31 MRI). Similarly, the overall sensitivity of imaging for HSV encephalitis was ∼80% for both CT and MRI, whereas for ADEM it was 0% for CT and 20% for MRI. MRI specificity for HSV encephalitis between 3–10 days after symptom onset was 100%.

Conclusion

There is a subjective component to scan interpretation that can have important implications for the clinical management of encephalitis cases. Neuroradiologists were good at diagnosing HSV encephalitis; however, agreement was worse for ADEM and other alternative aetiologies. Findings highlight the importance of a comprehensive and multidisciplinary approach to diagnosing the cause of encephalitis that takes into account individual clinical, microbiological, and radiological features of each patient.

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We assessed the role of imaging in encephalitis.

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We assessed the agreement between raters on scan interpretation.

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Diagnosis for herpes simplex encephalitis (HSE) was good.

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Agreement was worse for ADEM and other alternative aetiologies.

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HSE can be dismissed if MRI normal 72 hours after neurological symptom onset (with negative CSF tests).

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

Characteristic Cytokine and Chemokine Profiles in Encephalitis of Infectious, Immune-Mediated, and Unknown Aetiology

Background

Encephalitis is parenchymal brain inflammation due to infectious or immune-mediated processes. However, in 15–60% the cause remains unknown. This study aimed to determine if the cytokine/chemokine-mediated host response can distinguish infectious from immune-mediated cases, and whether this may give a clue to aetiology in those of unknown cause.

Methods

We measured 38 mediators in serum and cerebrospinal fluid (CSF) of patients from the Health Protection Agency Encephalitis Study. Of serum from 78 patients, 38 had infectious, 20 immune-mediated, and 20 unknown aetiology. Of CSF from 37 patients, 20 had infectious, nine immune-mediated and eight unknown aetiology.

Results

Heat-map analysis of CSF mediator interactions was different for infectious and immune-mediated cases, and that of the unknown aetiology group was similar to the infectious pattern. Higher myeloperoxidase (MPO) concentrations were found in infectious than immune-mediated cases, in serum and CSF (p = 0.01 and p = 0.006). Serum MPO was also higher in unknown than immune-mediated cases (p = 0.03). Multivariate analysis selected serum MPO; classifying 31 (91%) as infectious (p = 0.008) and 17 (85%) as unknown (p = 0.009) as opposed to immune-mediated. CSF data also selected MPO classifying 11 (85%) as infectious as opposed to immune-mediated (p = 0.036). CSF neutrophils were detected in eight (62%) infective and one (14%) immune-mediated cases (p = 0.004); CSF MPO correlated with neutrophils (p<0.0001).

Conclusions

Mediator profiles of infectious aetiology differed from immune-mediated encephalitis; and those of unknown cause were similar to infectious cases, raising the hypothesis of a possible undiagnosed infectious cause. Particularly, neutrophils and MPO merit further investigation.

Post-malaria neurological syndrome or viral encephalitis?

We present a case of a 60-year-old Caucasian man recently returned from Angola, where he had been successfully treated for a severe (non-cerebral) falciparum malaria infection. He was presented to the emergency room, with a subacute onset encephalopathy, ataxia and a generalised tonic-clonic seizure. Cerebrospinal fluid (CSF) analysis revealed lymphocytic pleocytosis (123 cells/µL) and hyperproteinorrhachia (188 mg/dL). Brain MRI and EEG were unremarkable. CSF PCR testing for neurotropic viruses was negative as were CSF and blood cultures. The patient was treated with ceftriaxone and acyclovir, with full recovery on the second day of treatment. We believe post-malaria neurological syndrome, a rare self-limited encephalopathy, should be considered in the differential diagnosis. Nevertheless, the presentation, lack of changes on brain MRI and EEG, along with possible false-negative CSF viral PCR, could still represent a viral encephalitis, which brings to question the treatment approach to adopt (conservative vs wide spectrum antiviral plus antibiotics).

Virus and Immune-Mediated Encephalitides: Epidemiology, Diagnosis, Treatment, and Prevention

Virus encephalitis remains a major cause of acute neurological dysfunction and permanent disability among children worldwide. Although some disorders, such as measles encephalomyelitis, subacute sclerosing panencephalitis, and varicella-zoster virus-associated neurological conditions, have largely disappeared in resource-rich regions because of widespread immunization programs, other disorders, such as herpes simplex virus encephalitis, West Nile virus-associated neuroinvasive disease, and nonpolio enterovirus-induced disorders of the nervous system, cannot be prevented. Moreover, emerging viral disorders pose new, potential threats to the child's nervous system. This review summarizes current information regarding the epidemiology of virus encephalitis, the diagnostic methods available to detect central nervous system infection and identify viral pathogens, and the available treatments. The review also describes immune-mediated disorders, including acute disseminated encephalomyelitis and N-methyl-D-aspartate receptor antibody encephalitis, conditions that mimic virus encephalitis and account for a substantial proportion of childhood encephalitis.

Reactivation of herpes simplex type 1 in pneumococcal meningitis

BACKGROUND

Acute bacterial meningitis (ABM) and herpes simplex type 1 (HSV-1) encephalitis are two rare but serious infections affecting the central nervous system (CNS). Concurrent bacterial and viral CNS infection has occasionally been reported.

OBJECTIVES

To illustrate the possibility of intrathecal infection with both Streptococcus pneumonia and HSV-1 by presenting a case and to examine whether herpesvirus reactivation is common in ABM.

STUDY DESIGN

We report a case diagnosed with HSV-1 reactivation in the cerebrospinal fluid (CSF) during treatment for pneumococcal ABM. A retrospective analysis of CSF samples from 21 patients with ABM was performed, with analysis of DNA from HSV-1 and four other neurotropic herpesviruses.

RESULTS

All 21CSF samples were negative for HSV-1, HSV-2, varicella zoster-virus, Epstein-Barr virus and human herpesvirus 6 DNA by PCR.

CONCLUSIONS

Although herpesvirus infection does not seem to be a common phenomenon in ABM we suggest that HSV-1 reactivation could be kept in mind if patients with ABM show symptoms or signs compatible with encephalitis.

Human herpesvirus infections of the central nervous system: laboratory diagnosis based on DNA detection by nested PCR in plasma and cerebrospinal fluid samples

Infections of the central nervous systems (CNS) present a diagnostic problem for which an accurate laboratory diagnosis is essential. Invasive practices, such as cerebral biopsy, have been replaced by obtaining a polymerase chain reaction (PCR) diagnosis using cerebral spinal fluid (CSF) as a reference method. Tests on DNA extracted from plasma are noninvasive, thus avoiding all of the collateral effects and patient risks associated with CSF collection. This study aimed to determine whether plasma can replace CSF in nested PCR analysis for the detection of CNS human herpesvirus (HHV) diseases by analysing the proportion of patients whose CSF nested PCR results were positive for CNS HHV who also had the same organism identified by plasma nested PCR. In this study, CSF DNA was used as the "gold standard," and nested PCR was performed on both types of samples. Fifty-two patients with symptoms of nervous system infection were submitted to CSF and blood collection. For the eight HHV, one positive DNA result-in plasma and/or CSF nested PCR-was considered an active HHV infection, whereas the occurrence of two or more HHVs in the same sample was considered a coinfection. HHV infections were positively detected in 27/52 (51.9%) of the CSF and in 32/52 (61.5%) of the plasma, difference not significant, thus nested PCR can be performed on plasma instead of CSF. In conclusion, this findings suggest that plasma as a useful material for the diagnosis of cases where there is any difficulty to perform a CSF puncture.

Prevalence of human Herpesviridae in cerebrospinal fluid of patients with multiple sclerosis and noninfectious neurological disease in the Netherlands

Prevalence of eight human herpesviruses (HHV1-8) was determined by real-time PCR in cell-rich cerebrospinal fluid (CSF) samples, obtained early after disease symptoms, of Dutch patients with multiple sclerosis (MS) and other noninfectious central nervous system diseases (NIND). Whereas HHV1-8 DNA was undetectable in CSF samples of MS patients, HHV6 DNA was detected in a plexus neuritis case and HHV7 DNA in an ependymoma and a Behçets' disease patient. However, intrathecal HHV infection was not detected. Data indicate that HHV1-8 are rarely detected in CSF of Dutch NIND patients and do not support the role of intrathecal HHV infection early after onset of disease symptoms in MS.

Laboratory diagnosis of viral infection

Since the last Handbook of Clinical Neurology volume on this topic, viral diagnosis has made tremendous strides, moving from the margin to the mainstream of clinical care. For many years, conventional virus isolation was the mainstay of viral diagnosis since it was sensitive and “open-minded.” However, growth in conventional cell culture entails an inherent delay that limits its clinical impact. Although rapid culture and viral antigen methods detect fewer pathogens and are less sensitive than conventional culture, both require less expertise and have greatly reduced time to result. Polymerase chain reaction has ushered in a new era in virology, especially in the diagnosis of neurologic diseases. Molecular amplification methods are rapid, highly sensitive, can be automated, quantitative, and detect viruses not amenable to routine culture. User-friendly, walk-away tests with results in an hour, as well as multiplex tests that can detect 20 viruses in a single reaction, are now a reality. As the variety of test methods and commercial products proliferate, the challenges for clinicians and laboratories are selecting which tests to utilize in which clinical scenarios, and understanding how to interpret the results. The advantages and limitations of each method are discussed in this chapter, with special attention to neurologic disease.

Nervous System Complications of Systemic Viral Infections

Invasion of the central nervous system (CNS) by viral agents typically produces a meningoencephalitis in which either meningitis or encephalitis may predominate. Viruses may also infect cranial or spinal blood vessels to produce ischemic injury. Viral and other infections may also elicit a host immune response which is cross-reactive with components of the neural tissue, resulting in encephalomyelitis, transverse myelitis, injury to peripheral nerves, or optic neuritis. This chapter discusses the pathogenesis of CNS viral infections and reviews clinical features of these disorders, major agents responsible in immunocompromised and immunocompetent individuals, and treatment. Prion diseases and postinfectious viral CNS syndromes including postinfectious encephalomyelitis, acute hemorrhagic leukoencephalitis, cerebellar ataxia, and transverse myelitis are also discussed.

Detection of human herpesviruses in the cerebrospinal fluid from patients diagnosed with or suspected of having progressive multifocal leukoencephalopathy

BACKGROUND

Progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease caused by JC virus (JCV), occurs mainly in immunocompromised patients. While JCV DNA is detected in the cerebrospinal fluid (CSF) from a certain proportion of patients suspected of having PML, JCV-negative patients may also develop brain lesions due to other infectious agents. This study assessed the prevalence of six herpesviruses in the CSF from patients diagnosed with or suspected of PML.

METHODS

Two hundred and ninety-nine CSF specimens and clinical data were collected from 255 patients, including 31 confirmed PML cases. Quantitative PCR assays were carried out to detect the genomic DNA of JCV, herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV-6).

RESULTS

Herpesvirus DNAs were detected in the CSF specimens from 29 of 255 patients (11.4%). HSV-1 and CMV were detected in JCV-negative patients, whereas VZV and EBV were detected in both CSF JCV-positive and -negative individuals. The herpesvirus-positive patients had underlying disorders that caused immunosuppression, such as HIV infection, congenital immunodeficiencies, and hematologic malignancies, and presented with neurologic symptoms and MRI lesions, mainly in the cerebral white matter. The median values of CSF cell counts and protein levels in the herpesvirus-positive patients were slightly higher than those in the PML patients.

CONCLUSIONS

The results demonstrate that herpesviruses are occasionally detected in the CSF from PML patients and immunocompromised individuals suspected of having PML. Thus, this study provides a significant basis for the diagnosis and treatment of neurological disorders in immunocompromised patients.

Viral encephalitis in the ICU

Viral encephalitis causes an altered level of consciousness, which may be associated with fever, seizures, focal deficits, CSF pleocytosis, and abnormal neuroimaging. Potential pathogens include HSV, VZV, enterovirus, and in some regions, arboviruses. Autoimmune (eg, anti-NMDA receptor) and paraneoplastic encephalitis are responsible for some cases where no pathogen is identified. Indications for ICU admission include coma, status epilepticus and respiratory failure. Timely initiation of anti-viral therapy is crucial while relevant molecular and serological test results are being performed. Supportive care should be directed at the prevention and treatment of cerebral edema and other physiological derangements which may contribute to secondary neurological injury.

Management of herpesvirus infections

Management of human herpesviruses remains a considerable clinical challenge, in part due to their ability to cause both lytic and latent disease. Infection with the Herpesviridae results in lifelong infection, which can reactivate at any time. Control of herpesviruses is by the innate and adaptive immune systems. Herpesviruses must evade the host innate immune system to establish infection. Once infected, the adaptive immune response, primarily CD8(+) T-cells, is crucial in establishing and maintaining latency. Latent herpesviruses are characterised by the presence of viral DNA in infected cells and limited or no viral replication. These characteristics provide a challenge to clinicians and those developing antiviral agents. The scope of this review is two-fold. First, to provide an overview of all antivirals used against herpesviruses, including their mechanism of action, pharmacokinetics, side effects, resistance and clinical uses. And second, to address the management of each of the eight herpesviruses both in the immunocompetent and immunocompromised host, providing evidence for clinical management and therapeutic options, which is important to the clinician engaged in the management of these infections.