Relapse of Herpes Simplex Encephalitis After Conventional Acyclovir Therapy

Antiviral treatment in schizophrenia: a randomized pilot PET study on the effects of valaciclovir on neuroinflammation

BACKGROUND

Patients with schizophrenia experience cognitive impairment, which could be related to neuroinflammation in the hippocampus. The cause for such hippocampal inflammation is still unknown, but it has been suggested that herpes virus infection is involved. This study therefore aimed to determine whether add-on treatment of schizophrenic patients with the anti- viral drug valaciclovir would reduce hippocampal neuroinflammation and consequently improve cognitive symptoms.

METHODS

We performed a double-blind monocenter study in 24 male and female patients with schizophrenia, experiencing active psychotic symptoms. Patients were orally treated with the anti-viral drug valaciclovir for seven consecutive days (8 g/day). Neuroinflammation was measured with Positron Emission Tomography using the translocator protein ligand [11C]-PK11195, pre-treatment and at seven days post-treatment, as were psychotic symptoms and cognition.

RESULTS

Valaciclovir treatment resulted in reduced TSPO binding (39%) in the hippocampus, as well as in the brainstem, frontal lobe, temporal lobe, parahippocampal gyrus, amygdala, parietal lobe, occipital lobe, insula and cingulate gyri, nucleus accumbens and thalamus (31-40%) when using binding potential (BPND) as an outcome. With total distribution volume (VT) as outcome we found essentially the same results, but associations only approached statistical significance (p = 0.050 for hippocampus). Placebo treatment did not affect neuroinflammation. No effects of valaciclovir on psychotic symptoms or cognitive functioning were found.

CONCLUSION

We found a decreased TSPO binding following antiviral treatment, which could suggest a viral underpinning of neuroinflammation in psychotic patients. Whether this reduced neuroinflammation by treatment with valaciclovir has clinical implications and is specific for schizophrenia warrants further research.

Immunomodulatory Strategies in Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 (HSV-1) can be responsible for life-threatening HSV encephalitis (HSE). The mortality rate of patients with HSE who do not receive antiviral treatment is 70%, with most survivors suffering from permanent neurological sequelae. The use of intravenous acyclovir together with improved diagnostic technologies such as PCR and magnetic resonance imaging has resulted in a reduction in the mortality rate to close to 20%. However, 70% of surviving patients still do not recover complete neurological functions. Thus, there is an urgent need to develop more effective treatments for a better clinical outcome. It is well recognized that cerebral damage resulting from HSE is caused by viral replication together with an overzealous inflammatory response. Both of these processes constitute potential targets for the development of innovative therapies against HSE. In this review, we discuss recent progress in therapy that may be used to ameliorate the outcome of patients with HSE, with a particular emphasis on immunomodulatory agents. Ideally, the administration of adjunctive immunomodulatory drugs should be initiated during the rise of the inflammatory response, and its duration should be limited in time to reduce undesired effects. This critical time frame should be optimized by the identification of reliable biomarkers of inflammation.

Herpes simplex virus infections in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of HSV in the pre- and post-transplant period. A majority of transplant recipients are seropositive for HSV-1 or 2. Compared with immunocompetent persons, SOT recipients shed HSV more frequently, have more severe clinical manifestations, and are slower to respond to therapy. Most HSV infection is diagnosed on clinical grounds, but patients may present with atypical lesions and/or other clinical manifestations. Acquisition from the donor is rare. Polymerase chain reaction is the preferred diagnostic test unless culture is needed for resistance testing. For limited mucocutaneous lesions, oral therapy can be used; however, in severe, disseminated, visceral or CNS involvement, acyclovir doses of up to 10 mg/kg every 8 hours intravenously should be initiated. Acyclovir-resistant HSV is less common in SOT patients than in HSCT and can be treated with foscarnet, though other novel therapies are currently under investigation. HSV-specific prophylaxis should be considered for all HSV-1 and HSV-2-seropositive organ recipients who are not receiving antiviral medication for CMV prevention that has activity against HSV.

Critical Care Viral Infections

Viral infections are a common cause of critical illness, particularly of the respiratory, gastrointestinal, and central nervous systems. Most are managed by supportive care alone. Early identification is critical to proper care to facilitate antimicrobial de-escalation. A small subset of viruses has directed treatment, and critical care providers should be knowledgeable about the diagnosis and treatment of influenza, herpes simplex meningoencephalitis, and viral hepatitis. Antivirals can reduce the morbidity and mortality associated with each of these illnesses.

Global dynamics of an epidemiological model with age of infection and disease relapse

In this paper, an epidemiological model with age of infection and disease relapse is investigated. The basic reproduction number for the model is identified, and it is shown to be a sharp threshold to completely determine the global dynamics of the model. By analysing the corresponding characteristic equations, the local stability of a disease-free steady state and an endemic steady state of the model is established. By means of suitable Lyapunov functionals and LaSalle's invariance principle, it is verified that if the basic reproduction number is less than unity, the disease-free steady state is globally asymptotically stable, and hence the disease dies out; if the basic reproduction number is greater than unity, the endemic steady state is globally asymptotically stable and the disease becomes endemic.

Infections in Neurocritical Care

Neurointensive care (NICU) patients experience complex infectious disease challenges. Central nervous system (CNS) infections are difficult to diagnose and treat, and post-neurosurgical patients are vulnerable to a unique set of healthcare-acquired infections (HAI) in addition to those typical of critically ill patients. The purpose of this review is to summarize the approach to suspected infection in the NICU and discuss management of several infectious syndromes in the NICU setting.

Neurological Disorders Associated with Human Alphaherpesviruses

Herpes simplex virus (HSV) encephalitis is the most common cause of sporadic fatal encephalitis worldwide, and central nervous system (CNS) involvement is observed in approximately one-third of neonatal HSV infections . In recent years, single-gene inborn errors of innate immunity have been shown to be associated with susceptibility to HSV encephalitis . Temporal lobe abnormalities revealed by magnetic resonance imaging-the most sensitive imaging method for HSV encephalitis-are considered strong evidence for the disease. Detection of HSV DNA in the cerebrospinal fluid by polymerase chain reaction (PCR) is the gold standard for the diagnosis of HSV encephalitis and neonatal meningoencephalitis. Intravenous acyclovir for 14-21 days is the standard treatment in HSV encephalitis. Neurological outcomes in neonates are improved by intravenous high-dose acyclovir for 21 days followed by oral acyclovir suppressive therapy for 6 months. Varicella-zoster virus (VZV) causes a wide range of CNS manifestations. VZV encephalitis typically occurs after primary infection, and reactivation of VZV may cause encephalitis. On the other hand, VZV infection of cerebral arteries produces vasculopathy, which can manifest as ischemic stroke. Vasculopathy can occur after primary infection or reactivation of VZV. PCR detection of VZV DNA in the cerebrospinal fluid can be used for the diagnosis of encephalitis or vasculopathy. Although there are no controlled treatment trials to assess VZV treatments of encephalitis or vasculopathy, intravenous acyclovir is a common treatment.

Management of Viral Central Nervous System Infections: A Primer for Clinicians

Viruses are a common cause of central nervous system (CNS) infections with many host, agent, and environmental factors influencing the expression of viral diseases. Viruses can be responsible for CNS disease through a variety of mechanisms including direct infection and replication within the CNS resulting in encephalitis, infection limited to the meninges, or immune-related processes such as acute disseminated encephalomyelitis. Common pathogens including herpes simplex virus, varicella zoster, and enterovirus are responsible for the greatest number of cases in immunocompetent hosts. Other herpes viruses (eg, cytomegalovirus, John Cunningham virus) are more common in immunocompromised hosts. Arboviruses such as Japanese encephalitis virus and Zika virus are important pathogens globally, but the prevalence varies significantly by geographic region and often season. Early diagnosis from radiographic evidence and molecular (eg, rapid) diagnostics is important for targeted therapy. Antivirals may be used effectively against some pathogens, although several viruses have no effective treatment. This article provides a review of epidemiology, diagnostics, and management of common viral pathogens in CNS disease.

Herpes Simplex Encephalitis: an Update

PURPOSE OF REVIEW

The goal of this review is to provide an update on current thinking regarding herpes simplex encephalitis (HSE), emphasizing new information about pathogenesis, diagnosis, and immune responses. Specific questions to be addressed are the following: (1) Is there a genetic predisposition to HSE? (2) What clinical approaches have the greatest impact on improving the long-term outcomes in patients with HSE? And (3) are there immune-mediated mechanisms that may account for relapsing HSE?

RECENT FINDINGS

Toll-like receptor 3 (TLR 3) plays an important role in innate immune responses, including generation of interferons. Multiple single-gene errors in TLR 3 interferon pathways have recently been described in children that result in increased susceptibility to HSE. Conversely, studies in both animal models and humans indicate that both cytolytic viral replication and immune-mediated responses (including cytotoxic T lymphocytes and immune mechanisms mediated by TLR 2) contribute to the pathology of HSV, suggesting possible new therapeutic approaches. In terms of treatment, data clearly indicate that a longer duration between onset of symptoms and initiation of effective antiviral therapy correlates directly with less favorable clinical outcome. Recurrent or relapsing HSE may occasionally occur, but recent observations indicate that many instances of "relapsing HSE", especially in children, are more often anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis triggered by the antecedent HSV infection. Innate immune responses are critical for defense against HSV; genetic defects in this system may predispose patients to HSE. During acute HSE, exuberant immune responses may contribute to the CNS pathology, suggesting that selective immunosuppressive therapy, coupled with potent antiviral drugs, may eventually play a role in the therapeutic management of HSV. While overall clinical outcomes of HSE remain suboptimal, the initiation of high-dose acyclovir therapy as early as possible in the course of the illness provides the best chance for a patient to survive with minimal neurologic damage. Distinguishing relapsing HSE from autoimmune anti-NMDAR antibody encephalitis is critically important because therapeutic approaches will be very different.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

Herpetic infections have plagued humanity for thousands of years, but only recently have advances in antiviral medications and supportive treatments equipped physicians to combat the most severe manifestations of disease. Prompt recognition and treatment can be life-saving in the care of patients with herpes simplex-1 virus encephalitis, the most commonly identified cause of sporadic encephalitis worldwide. Clinicians should be able to recognize the clinical signs and symptoms of the infection and familiarize themselves with a rational diagnostic approach and therapeutic modalities, as early recognition and treatment are key to improving outcomes. Clinicians should also be vigilant for the development of acute complications, including cerebral edema and status epilepticus, as well as chronic complications, including the development of autoimmune encephalitis associated with antibodies to the N-methyl-D-aspartate receptor and other neuronal cell surface and synaptic epitopes. Herein, we review the pathophysiology, differential diagnosis, and clinical and radiological features of herpes simplex virus-1 encephalitis in adults, including a discussion of the most common complications and their treatment. While great progress has been made in the treatment of this life-threatening infection, a majority of patients will not return to their previous neurologic baseline, indicating the need for further research efforts aimed at improving the long-term sequelae.

HSV encephalitis-induced anti-NMDAR encephalitis in a 67-year-old woman: report of a case and review of the literature

Herpes simplex virus (HSV) encephalitis can induce an autoimmune encephalitis mediated by autoantibodies against the N-methyl-D-aspartate receptor (NMDAR). Post-HSV NMDAR encephalitis and de novo NMDAR encephalitis have been more commonly described in children and young adults. We describe the case of a 67-year-old woman with post-HSV NMDAR encephalitis and review the relevant literature. Clinical, serological, neurophysiological, and imaging evaluations were undertaken in the evaluation of this patient. A literature review was performed. Nearly 2 months after a typical course of HSV encephalitis confirmed by HSV polymerase chain reaction studies from the spinal fluid and treated with intravenous acyclovir, a 67-year-old woman suffered neurological deterioration. There was no evidence of active HSV infection, but NMDAR antibodies were found in her serum and spinal fluid. The patient improved after initiation of immunosuppressive therapy. All patients who experience new or recurrent neurological symptoms following recovery from HSV encephalitis should be evaluated for post-infectious autoimmune encephalitis, including NMDAR encephalitis.

Global Stability of a Delayed SIRI Epidemic Model with Nonlinear Incidence

In this paper we propose the global dynamics of an SIRI epidemic model with latency and a general nonlinear incidence function. The model is based on the susceptible-infective-recovered (SIR) compartmental structure with relapse (SIRI). Sufficient conditions for the global stability of equilibria (the disease-free equilibrium and the endemic equilibrium) are obtained by means of Lyapunov-LaSalle theorem. Also some numerical simulations are given to illustrate this result.

Update on herpes virus infections of the nervous system

Herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) are human neurotropic viruses that establish latent infection in dorsal root ganglia (DRG) for the entire life of the host. From the DRG they can reactivate to cause human morbidity and mortality. Although they vary, in part, in the clinical disorders they cause, and in their molecular structure, they share several features that govern the biology of their infection of the human nervous system. HSV-1 is the causative agent of encephalitis, corneal blindness, and several peripheral nervous system disorders; HSV-2 is responsible for meningoencephalitis in neonates and meningitis in adults. The biology of their ability to establish latency, maintain it for the entire life of the host, reactivate, and cause primary and recurrent disease is being studied in animal models and in humans. This review covers recent advances in understanding the biology and pathogenesis of HSV-related disease.

Modelling diseases with relapse and nonlinear incidence of infection: a multi-group epidemic model

In this paper, we introduce a basic reproduction number for a multi-group SIR model with general relapse distribution and nonlinear incidence rate. We find that basic reproduction number plays the role of a key threshold in establishing the global dynamics of the model. By means of appropriate Lyapunov functionals, a subtle grouping technique in estimating the derivatives of Lyapunov functionals guided by graph-theoretical approach and LaSalle invariance principle, it is proven that if it is less than or equal to one, the disease-free equilibrium is globally stable and the disease dies out; whereas if it is larger than one, some sufficient condition is obtained in ensuring that there is a unique endemic equilibrium which is globally stable and thus the disease persists in the population. Furthermore, our results suggest that general relapse distribution are not the reason of sustained oscillations. Biologically, our model might be realistic for sexually transmitted diseases, such as Herpes, Condyloma acuminatum, etc.

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.

Pediatric herpes simplex virus encephalitis: a retrospective multicenter experience

Knowledge on pediatric herpes simplex virus encephalitis is limited. Here we summarize 6 neonates and 32 children diagnosed by polymerase chain reaction (n = 37) or serological studies (n = 1), respectively. Diagnosis was difficult, as only 15 patients presented neurologic symptoms. Moreover, cerebrospinal fluid glucose, protein, and leukocytes were normal in 6 patients. Subsequently, all but 2 showed neurologic symptoms. Diffusion-weighted neuroimaging was the most sensitive early imaging method. Despite acyclovir treatment, 8 patients experienced early relapses, showing movement abnormalities, impaired vigilance, and seizures. Diffuse white matter changes, found in 3 of 5 relapse patients on neuroimaging, and a negative cerebrospinal fluid herpes simplex virus polymerase chain reaction suggested inflammatory processes. All relapse patients were again treated with acyclovir, and 3 responded to additional corticosteroid treatment. Whereas outcome after relapses was poor, overall outcome was good. No child died; 14 were asymptomatic at discharge, and neuroimaging remained normal in 7 of 30 patients studied.

Herpes simplex virus-1 encephalitis: a review of current disease management with three case reports

Herpes simplex virus-1 (HSV-1) is the most common cause of lethal sporadic encephalitis. Despite improved therapy with intraveneous acyclovir, HSV-1 encephalitis is associated with persistent severe neurological deficits. We report three cases of adult patients with HSV-1 encephalitis (HSE), discuss the current accepted guidelines for treatment as published by the Infectious Disease Society of America (IDSA) and review the literature pertaining to HSE. Our case presentations are consistent with the literature review noting a broad spectrum of clinical outcomes with HSE. We include the first published case of successful early transition to oral antiviral therapy. In the other two cases, repeat cerebrospinal fluid (CSF) analysis showed persistent lymphocytic pleocytosis necessitating prolonged viral suppression. Long-term neurological sequelae were noted in these two patients. The IDSA recommendation of 2-3 weeks of intraveneous acyclovir at 10 mg/kg every 8 h, depending on the clinical course, is sufficient for most cases of HSE. We recommend individualization of duration of treatment based on follow-up CSF analysis with quantification of HSV-1.

GLOBAL DYNAMICS OF A MULTI-GROUP EPIDEMIC MODEL WITH GENERAL RELAPSE DISTRIBUTION AND NONLINEAR INCIDENCE RATE

In this paper, we investigate a class of multi-group epidemic models allowing heterogeneity of the host population and that has taken into consideration with general relapse distribution and nonlinear incidence rate. We establish that the global dynamics are completely determined by the basic reproduction number R0. The proofs of the main results utilize the persistence theory in dynamical systems, Lyapunov functionals and a subtle grouping technique in estimating the derivatives of Lyapunov functionals guided by graph-theoretical approach. Biologically, the disease (with any initial inoculation) will persist in all groups of the population and will eventually settle at a constant level in each group. Furthermore, our results demonstrate that heterogeneity and nonlinear incidence rate do not alter the dynamical behaviors of the basic SIR model. On the other hand, the global dynamics exclude the existence of Hopf bifurcation leading to sustained oscillatory solutions.

Management of suspected viral encephalitis in adults--Association of British Neurologists and British Infection Association National Guidelines

In the 1980s the outcome of patients with herpes simplex encephalitis was shown to be dramatically improved with aciclovir treatment. Delays in starting treatment, particularly beyond 48 h after hospital admission, are associated with a worse prognosis. Several comprehensive reviews of the investigation and management of encephalitis have been published. However, their impact on day-to day clinical practice appears to be limited. The emergency management of meningitis in children and adults was revolutionised by the introduction of a simple algorithm as part of management guidelines. In February 2008 a group of clinicians met in Liverpool to begin the development process for clinical care guidelines based around a similar simple algorithm, supported by an evidence base, whose implementation is hoped would improve the management of patients with suspected encephalitis.

Management of suspected viral encephalitis in children - Association of British Neurologists and British Paediatric Allergy, Immunology and Infection Group national guidelines

In the 1980s the outcome of patients with herpes simplex encephalitis was shown to be dramatically improved with aciclovir treatment. Delays in starting treatment, particularly beyond 48 h after hospital admission, are associated with a worse prognosis. Several comprehensive reviews of the investigation and management of encephalitis have been published. However, their impact on day-to-day clinical practice appears to be limited. The emergency management of meningitis in children and adults was revolutionised by the introduction of a simple algorithm as part of management guidelines. In February 2008 a group of clinicians met in Liverpool to begin the development process for clinical care guidelines based around a similar simple algorithm, supported by an evidence base, whose implementation is hoped would improve the management of patients with suspected encephalitis.

Herpes simplex virus encephalitis: new infection or reactivation?

PURPOSE OF REVIEW

This review describes the pathogenesis, clinical presentation, course, and therapy of herpes simplex encephalitis (HSE), the most fatal viral encephalitis, in which prognosis is dependent on early diagnosis and effective therapy.

RECENT FINDINGS

Herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) are human neurotropic viruses that establish latent infection in dorsal-root ganglia for the entire life of the host. From this reservoir, they can reactivate to cause human morbidity and mortality. HSE is one of the most devastating disorders caused by these viruses. The biology of their ability to establish latency, maintain it for the entire life of the host, reactivate, and cause primary and recurrent disease is being studied in animal models and in humans. Of special interest is the question whether HSE is the result of primary infection or is it the outcome of reactivation. The present review covers the biological, medical, and neurological aspects of HSE, focusing among others on recent molecular findings of gene expression during latent infection of HSV-1.

SUMMARY

Despite accumulating knowledge, there are still several issues regarding both pathogenesis and therapy of HSV-1 that currently defy understanding.

Herpes simplex encephalitis and management of acyclovir in encephalitis patients in France

This study reports on the clinical profiles of herpes simplex encephalitis (HSE) case-patients and the management of acyclovir prescriptions. We designed a study on the causes of encephalitis in France in 2007. Case-patients fulfilling the inclusion criteria were enrolled in all the hospitals that volunteered to participate. Fifty-five of 253 enrolled case-patients were diagnosed with HSE. Three (5%) HSE patients died and 48 (89%) were discharged with persistent neurological symptoms. All HSE patients were prescribed acyclovir, 10 of whom had a 2-week course; 42 a 3-week course; two received incomplete courses; and one received two courses of 21 days each due to relapse. The acyclovir dosage was reported for 45 adult HSE patients, 25 (53%) of whom received 10 mg/kg t.i.d. and 22 (47%) received 15 mg/kg t.i.d. The mortality rate was low despite 49% of patients being admitted to intensive-care units. A high dose of acyclovir was not associated with a better outcome in HSE patients. Most patients had persisting symptoms on discharge suggesting neuropsychological rehabilitation is an important issue for survivors.

The neurotropic herpes viruses: herpes simplex and varicella-zoster

Herpes simplex viruses types 1 and 2 (HSV1 and HSV2) and varicella-zoster virus (VZV) establish latent infection in dorsal root ganglia for the entire life of the host. From this reservoir they can reactivate to cause human morbidity and mortality. Although the viruses vary in the clinical disorders they cause and in their molecular structure, they share several features that affect the course of infection of the human nervous system. HSV1 is the causative agent of encephalitis, corneal blindness, and several disorders of the peripheral nervous system; HSV2 is responsible for meningoencephalitis in neonates and meningitis in adults. Reactivation of VZV, the pathogen of varicella (chickenpox), is associated with herpes zoster (shingles) and central nervous system complications such as myelitis and focal vasculopathies. We review the biological, medical, and neurological aspects of acute, latent, and reactivated infections with the neurotropic herpes viruses.

Main adult herpes virus infections of the CNS

Herpes viruses are widely involved in human infectious diseases, and some are life threatening, such as CNS infections. These manifestations vary according to the type of virus involved and the immune status of the patient. This article will review the clinical manifestations (encephalitis, myelitis, meningitis and postinfectious encephalomyelitis), the diagnostic strategies and the presently used drugs (acyclovir, valacyclovir, ganciclovir, valgancyclovir, foscarnet and cidofovir). The review will also discuss drugs that are currently in the pipeline and that could be used in the future.

Chronic herpes simplex virus encephalitis in childhood

Although herpes simplex virus is a major cause of acute encephalitis in childhood, chronic herpes simplex virus encephalitis has only rarely been reported. This report presents a case of chronic herpes simplex virus encephalitis in a 6-year-old female. Diagnosis was based on the detection of herpes simplex virus deoxyribonucleic acid by polymerase chain reaction in combination with the cerebrospinal fluid/serum ratio of herpes simplex virus-specific immunoglobulin G, the presence of herpes simplex virus-specific oligoclonal immunoglobulin G bands in cerebrospinal fluid, and calcifications in the temporal regions found on cerebral computed tomographic scan. Prolonged antiviral therapy was beneficial to later mental development.

Current use of anti-infectives in dermatology

Dermatologic diseases encompass a broad category of pathologic situations. Infection remains a significant aspect of the pathology faced in patient encounters, and it is natural to expect that anti-infectives play a major element in the armamentarium utilized by dermatologists. Aside from the treatment of the classic bacterial and fungal infections, there are now new uses for antiviral agents to help suppress recurrent disease, such as herpes simplex. There is also the novel approach of using anti-infectives, or agents that have been thought to have antimicrobial activity, to treat inflammatory diseases. This review describes anti-infectives, beginning with common antibiotics used to treat bacterial infections. The discussion will then cover the current use of antivirals. Finally, the description of antifungals will be separated, starting with the oral agents and ending with the topical antimycotics. The use of anti-infectives in tropical dermatology has been purposefully left out, and perhaps should be the subject of a separate review. Cutaneous bacterial infections consist chiefly of those microorganisms that colonize the skin, such as species of staphylococcus and streptococcus. Propionibacterium acnes and certain other anaerobes can be involved in folliculitis, pyodermas and in chronic conditions such as hidradenitis suppurativa.

Molecular methods for diagnosis of viral encephalitis

Hundreds of viruses cause central nervous system (CNS) disease, including meningoencephalitis and postinfectious encephalomyelitis, in humans. The cerebrospinal fluid (CSF) is abnormal in >90% of cases; however, routine CSF studies only rarely lead to identification of a specific etiologic agent. Diagnosis of viral infections of the CNS has been revolutionized by the advent of new molecular diagnostic technologies to amplify viral nucleic acid from CSF, including PCR, nucleic acid sequence-based amplification, and branched-DNA assay. PCR is ideally suited for identifying fastidious organisms that may be difficult or impossible to culture and has been widely applied for detection of both DNA and RNA viruses in CSF. The technique can be performed rapidly and inexpensively and has become an integral component of diagnostic medical practice in the United States and other developed countries. In addition to its use for identification of etiologic agents of CNS disease in the clinical setting, PCR has also been used to quantitate viral load and monitor duration and adequacy of antiviral drug therapy. PCR has also been applied in the research setting to help discriminate active versus postinfectious immune-mediate disease, identify determinants of drug resistance, and investigate the etiology of neurologic disease of uncertain cause. This review discusses general principles of PCR and reverse transcription-PCR, including qualitative, quantitative, and multiplex techniques, with comment on issues of sensitivity, specificity, and positive and negative predictive values. The application of molecular diagnostic methods for diagnosis of specific infectious entities is reviewed in detail, including viruses for which PCR is of proven efficacy and is widely available, viruses for which PCR is less widely available or for which PCR has unproven sensitivity and specificity, and nonviral entities which can mimic viral CNS disease.

Herpes simplex: Encephalitis children and adolescents

Herpes simplex encephalitis (HSE) remains one of the most devastating infections of the central nervous system despite available antiviral therapy. Children and adolescents account for approximately one third of all cases of HSE. Clinical diagnosis is suggested in the encephalopathic, febrile patient with focal neurologic signs. However, these clinical findings are not pathognomonic because numerous other infections in the central nervous system can mimic HSE. Support for the diagnosis from a neurodiagnostic perspective is aided by the demonstration of disease of the temporal lobe by magnetic resonance image scan and spike and slow-wave activity on electroencephalogram. In the current era, the gold standard for establishing diagnosis is the detection of herpes simplex virus DNA in the cerebrospinal fluid by polymerase chain reaction (PCR). Although PCR is an excellent test and far more desirable than brain biopsy, false negatives can occur early after disease onset. Current therapeutic management calls for the administration of acyclovir at 10 mg/kg every 8 hours for 21 days. Even with early administration of therapy after the onset of disease, nearly two thirds of survivors will have significant residual neurologic deficits. Recent investigative efforts are assessing the value of PCR detection of viral DNA at the completion of therapy and the value of prolonged antiviral therapy.

Chronic Granulomatous Herpes Simplex Encephalitis in Children

Herpes simplex encephalitis is usually a monophasic acute illness but can cause chronic disease, particularly in children. Little information is available as to the histological substrate. We report the findings in 3 children. In 2 children, herpes encephalitis had occurred during the first 2 years, but both later developed intractable epilepsy that led to neurosurgery. The biopsies showed chronic granulomatous inflammation with foci of mineralization. One child made a good post-operative recovery. The other was found post-operatively to have herpes simplex virus type 1 (HSV-1) DNA and elevated titers of HSV IgM antibodies in the CSE He was given acyclovir but after initial improvement developed hemiparesis, with extensive signal change on MRI. Repeat biopsy revealed florid granulomatous inflammation with necrosis. The third patient was an infant who had had a cutaneous facial HSV-2 eruption soon after birth. This was treated with topical acyclovir, after which she remained well until 2 months, when she presented with a relatively non-specific illness, developed blisters of the right hand and foot, and died a few days later. Necropsy revealed severe granulomatous encephalitis, most extensive in the temporal lobe and insula, and associated with mineralization. Our findings indicate that herpes simplex encephalitis in children can be complicated by chronic granulomatous inflammation with mineralization. This pattern of disease may be an under-recognized complication of herpes simplex infection during the first few years of life.

Exacerbation of herpes simplex encephalitis after successful treatment with acyclovir

Herpes simplex encephalitis (HSE) in children sometimes exacerbates after successful treatment; yet the frequency, etiology, and clinical features of exacerbation remain unclear. We report data for 27 children with HSE confirmed by polymerase chain reaction (PCR) analysis; all were successfully treated with acyclovir, but 7 (26%) had a relapse of encephalitic illness. In 2 of those 7, serial examination with a PCR assay showed that herpes simplex virus (HSV) DNA reappeared temporarily in the cerebrospinal fluid (CSF). For 5 of the 7 patients, a second course of acyclovir therapy was effective. Coxsackievirus A9 was isolated from CSF of 1 case patient during subsequent exacerbation. The total dose during initial acyclovir therapy was significantly lower in the relapse group than in the control group (P=.027). In conclusion, exacerbation of HSE in children may be more common than previously recognized. It is suggested that the replication of HSV or another viral pathogen caused a second encephalitic illness (HSE) in some cases.

Rapid Diagnosis of Herpes Simplex Encephalitis Using Microchip Electrophoresis of PCR Products

Background: Herpes simplex virus (HSV) is the most common cause of acute sporadic encephalitis in the United States. PCR of DNA extracted from cerebrospinal fluid (CSF) allows for reliable diagnosis of herpes simplex encephalitis (HSE). A faster turnaround time for HSE testing would improve patient management and lead to better outcomes. The aims of this study, therefore, were to develop a microchip-based electrophoretic method for rapid detection of HSV PCR products, and to compare the performance characteristics of liquid hybridization/gel retardation as an established clinical PCR product detection method with the new microchip-based method.

Methods: The study examined archival DNA from 33 selected CSF specimens submitted for HSV PCR testing to the clinical laboratory. One aliquot of the HSV PCR product was analyzed by liquid hybridization/gel retardation analysis, and a second PCR aliquot was analyzed directly with a microchip capillary electrophoresis system using an instrument built in-house. PCR samples were introduced directly into the microchip without a desalting step by use of a novel fluidic interface. Channel surfaces on the glass microchip were silanized, followed by derivatization with polyvinylpyrrolidone.

Results: Of the 33 CSF specimens tested by liquid hybridization analysis of HSV PCR products, 10 tested positive for HSV DNA, 2 gave a weakly positive result, and 21 tested negative. Total analysis time for detection of HSV DNA by gel retardation assay was 18 h. Microchip electrophoresis provided identical results in <110 s/sample, achieving 100% sensitivity and specificity compared with the established method.

Conclusions: Microchip-based electrophoresis can rapidly and accurately separate HSV PCR products, giving results identical to those obtained by liquid hybridization but with substantially decreased turnaround time. Clinical implementation of the new method will help to improve patient management and outcomes.

Antiviral agents for non-human immunodeficiency virus infections

Several new agents for treating viral infections have been developed in recent years. All available agents are virustatic, inhibiting specific steps in the process of viral replication. No agent is active against nonreplicating or latent viruses. Acyclovir is useful in the treatment of genital herpes, herpes simplex encephalitis, mucocutaneous herpetic infection, varicella infection in the immunosuppressed host, and herpes zoster infection in the normal and the immunosuppressed host. It can also be used for prevention of herpesvirus infection in immunocompromised patients. Ganciclovir is indicated for the treatment of cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome and is effective in the treatment and prevention of cytomegalovirus infection in other immunocompromised patients. Famciclovir and valacyclovir are effective in the management of herpes simplex and varicella-zoster infection. Amantadine and rimantadine are useful therapeutically and prophylactically in the management of influenza A virus infection. Chronic hepatitis B infection can respond to lamivudine therapy, and the optimal treatment of hepatitis C is the combination of interferon alfa and ribavirin. Despite pronounced toxic effects, foscarnet and cidofovir are effective antiviral agents in specific settings.

[Recurrence of herpes simplex encephalitis]

Herpes simplex encephalitis (HSE) rarely occurs in children, is not easily diagnosed, and has a poor prognosis.

CASE REPORT

We report a pediatric case with a relapse on the 29th day despite conventional acyclovir therapy. As the relapse mechanism is not clearly understood, antiviral and immunosuppressive therapy was administered.

CONCLUSION

This case underlines the importance of clinical examination and the necessity of accurate testing prior stopping antiviral treatment. A better understanding of the relapse mechanism is required in order to propose more efficient treatment.

Herpes simplex encephalitis: a review

Patients with herpes simplex encephalitis generally have altered mental function and are rarely able to provide a good medical history. Failure to diagnose this serious disease may result in permanent neurologic damage or death of the patient. Rapid institution of newer diagnostic tests such as polymerase chain reaction for herpes simplex virus is essential for proper diagnosis. Parenteral acyclovir therapy is efficacious but, clearly, improvements in prevention and therapy are still important research goals. This review is meant to inform physicians and nurses concerning the current diagnosis and management of this treatable but potentially fatal illness.

Routine diagnosis of herpes simplex virus (HSV) encephalitis by an internal DNA controlled HSV PCR and an IgG-capture assay for intrathecal synthesis of HSV antibodies

BACKGROUND

The development of antiviral therapy increases the need for rapid, sensitive and reliable methods or combination of methods for diagnosis and monitoring herpes simplex encephalitis, HSE.

OBJECTIVES

Evaluation of diagnostic performance of three successively developed HSV PCR assays when combined with a new capture ELISA for HSV intrathecal antibody production (ITT).

STUDY DESIGN

During a 3.6 year period a total of 4.206 CSF and serum samples from about 4.140 hospitalized patients with a tentative diagnosis of HSE were analyzed by a new ELISA for ITT. 1.962 CSF samples were examined also by PCR. Clinical signs and symptoms and additional tests were obtained on all ITT and/or PCR positive patients. In 1993 the PCR was a double PCR. In 1994 the PCR was a single PCR with internal inhibition control. Positive samples were confirmed by a different confirmative PCR to increase the specificity. From 1995 the PCR was as in 1994 but samples were no longer divided in the serology routine laboratory.

RESULTS

A total of 33 HSE cases was found (incidence 1.8 HSE per million people). All patients were treated with aciclovir. Three patients died, 9 patients had primary infection, 2 patients had HSE previously, and 2 patients relapsed. Only 11 patients recovered satisfactory. Of all 37 positive ITT 7 were unlikely positive. False positive PCR was seen in 1993 and 1994, due to sample-to-sample contamination during division of samples, but was not seen since 1995 when this procedure was changed. The test results depended on the state of the disease. Thus, the sensitivity, specificity, PPV and NPV for ITT were highest when performed more than 1 week after debut of symptoms whereas these values were highest using PCR within the first week.

CONCLUSION

Routine PCR diagnosis of HSE type 1 and 2 is a highly sensitive and specific method that should be performed together with serological ITT to cover the whole time span from debut of symptoms to several weeks after hospitalization.

Advantage of polymerase chain reaction in the diagnosis of herpes simplex encephalitis: presentation of 5 atypical cases

Four case of herpes encephalitis (HSVE) are described. The diagnosis was established by polymerase chain reaction (PCR) assay of cerebrospinal fluid (CSF). These reports illustrate different situations in the clinical management of this disease. PCR was considered useful in confirming the HSVE diagnosis in 3 atypical cases, and in the differentiation between virologic failure and postinfectious encephalitis in a patient with recurrence of symptoms. A case with typical HSVE clinical findings is also reported where PCR was negative and a temporal lobe lymphoma was diagnosed at autopsy. This last case is representative of the utility of PCR in the management of other diseases mimicking HSVE.

Failure of acyclovir sodium therapy in herpes simplex encephalitis

Herpes simplex encephalitis is an important disease characterized by focal haemorrhagic necrosis of the temporal and frontal lobes of the brain. The mortality rate may be as high as 70% of untreated cases. Isolation of the virus from brain tissue is the most reliable means of diagnosis. Although some non-invasive diagnostic modalities have been investigated, none is as reliable as brain tissue sampling. Despite acceptance that acyclovir sodium is the most effective drug for treatment, there is not a consensus on the dosage and duration of the antiviral therapy because some patients fail to respond and sometimes there is recurrence following therapy. We report a case of encephalitis in a previously normal host who died after a 13-day course of acyclovir therapy with isolation of HSV-type 1 from the brain post mortem.

Polymerase chain reaction in the investigation of "relapse" following herpes simplex encephalitis

Five cases of apparent relapse of herpes encephalitis were investigated. All patients recovered after antiviral and corticosteroid therapy. Samples of CSF taken from the patients at intervals through the initial and subsequent encephalitic episode were examined. PCR amplification of a 351 bp sequence from the Herpesvirus simplex (HSV) thymidine kinase gene demonstrated the presence of HSV DNA in CSF taken during the initial encephalitic illness but not during the second encephalitic episode. Intrathecal synthesis of HSV antibody (HSV antibody index > 1.9) was observed in all cases following the first episode, and there appeared to be no significant increase in intrathecal antibody synthesis in the second episode. High levels of CSF myelin basic protein were found during the acute phases of both the initial and the subsequent encephalitic illnesses. These data suggest that at least in our series of five patients, relapse following HSE may not be due to active viral replication.

Relapse of herpes simplex encephalitis

We report five children who had recurrent central nervous system signs after conventional acyclovir therapy for herpes simplex encephalitis. Secondary exacerbation was characterized clinically by severe ballismic movement disorder in all five children, associated with fever, impairment of consciousness, and seizures. Biologic analysis in all children and magnetic resonance imaging and neuropathology studies of the brain in three cases were compatible with inflammatory reaction. In contrast, all viral cultures remained negative, herpes simplex virus antigen in one child and DNA tested by polymerase chain reaction in four children were undetectable in the first samples of cerebrospinal fluid during the relapse, suggesting a postinfectious, immune-mediated mechanism of relapse in these patients.

Choreoathetosis as an initial sign of relapsing of herpes simplex encephalitis

Twelve children with type 1 herpes simplex encephalitis (3 with relapse, 9 without) have been monitored during the past 7 years. Ten of the children received intravenous infusion of acyclovir (30 mg/kg/day) for 10 days, 1 child who experienced relapse received 15 mg/kg/day, and another relapsed child received no antiviral agents until relapse. Relapse occurred 20-36 days after initial onset. All relapsed patients underwent another 10 days of acyclovir treatment (30 mg/kg/day). Choreoathetosis appeared as the initial sign of relapse followed by rapidly progressive unresponsiveness in all 3 relapsed patients: in 1 nonrelapsed patient choreoathetosis occurred during the recovery period. In these 4 patients involuntary movement was remitted within 3 months to 2 years. One patient with choreoathetosis died of measles pneumonia 4 months after onset of herpes simplex encephalitis and the surviving 3 were severely retarded. Although neuroimaging sparing of basal ganglia does not indicate structural and functional abnormalities, the disturbance of the neural connection among the basal ganglia and the cerebral cortex, which manifested severe damage over frontal, temporal, and parietal mantles on CT, may be the source of movement disorders in these patients. We conclude that choreoathetosis may be the first sign of relapse of herpes simplex encephalitis in children and may be an indicator of poor prognosis. The neuropathogenesis of choreoathetosis requires further investigation.

[Neonatal encephalitis caused by herpes simplex: immunohistochemical diagnosis of a case]

The authors report the case of a female newborn infant, who had seizures and vesicles at the nose and inferior lip since the fifth day of life. CSF changes suggested an encephalitis. Signs of neurologic and respiratory deterioration were followed by death. Partial cranial autopsy showed a necrohemorrhagic temporal encephalitis without intranuclear inclusions. Immunohistochemical examination by the avidin-biotin-peroxidase technique with polyclonal antibodies against Herpes simplex type 1 and type 2 was positive to type 2 Herpes simplex virus.

Relapse of herpes simplex encephalitis after acyclovir therapy

A case of herpes simplex encephalitis in a previously healthy 17-month-old girl relapsing 1 week after completion of a 10-day acyclovir therapy is described. The child responded favourably to a second 10-day course with acyclovir. The time of relapse and the satisfactory response to a second course of acyclovir treatment indicate that the first course of therapy was inadequate for eradication of herpes simplex virus infection.

Chorea as a presentation of herpes simplex encephalitis relapse

Three infants, ages 3 months to 3 years, presented with chorea as the initial manifestation of herpes simplex encephalitis (HSE) relapse. Patient 2, treated with repeated 10 day courses of 30 mg/kg/day of acyclovir, had no clear improvement in neurological status. Patient 1, treated with a repeated 10-day course, improved only to have another HSE relapse 4 years later. Patient 3 clearly improved soon after a 3-week course of acyclovir at conventional dosages. A fourth patient (Patient 4) who relapsed with chorea after what was thought to be HSE, and who did not respond to repeated acyclovir treatment, was negative for herpes simplex virus indicators on brain biopsy and DNA testing. We recommend treating all patients suffering from HSE with a minimum 3-week course of acyclovir at 30-35 mg/kg/day in 3 divided doses.

Antiviral agents

In recent years, the antiviral armamentarium has expanded considerably. Currently available agents are virustatic, inhibiting specific steps in the process of viral replication. No agent is active against nonreplicating or latent viruses. Acyclovir is useful in the treatment of genital herpes, herpes simplex encephalitis, mucocutaneous herpetic infection, varicella infection in the immunosuppressed host, and herpes zoster infection in the normal and the immunosuppressed host. It can also be used for prevention of herpesvirus infection in immunocompromised patients. Ganciclovir is indicated for the treatment of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome (AIDS) and is effective in the management of organ-specific cytomegalovirus infection in other immunocompromised patients. Chronic hepatitis C and condyloma acuminatum due to human papillomavirus respond to therapy with interferon alfa-2b. Patients with human immunodeficiency virus infection and CD4 lymphocyte counts of less than 500 cells/mm3 should be treated with zidovudine. Amantadine is useful in a therapeutic and prophylactic role in the management of influenza A virus infection. With the expanded use of and indications for antiviral therapy, clinically significant resistance to these agents has been encountered with increasing frequency.