Infectious causes of acute flaccid paralysis

Thirteen-year surveillance results of acute flaccid paralysis cases in Southeast Turkey and the effect of refugee movements on surveillance results

OBJECTIVE

Acute flaccid paralysis (AFP) is a major neurological problem. Turkey has accepted over 4 million refugees since 2011 due to the wars in neighbouring countries. In the long term, refugees can have adverse effects on the limited resources of health, sanitation, water supply, foodstuff, and shelter services of host countries, precipitating the transmission and spread of enteroviruses causing AFP. This study examines the 13-year surveillance and incidence of AFP cases in southeast Turkey, and questions possible impact of refugee movements on these parameters, comparing the periods before (2007-2010) and after (2011-2019) 2011, when the refugee movements emerged.

METHODS

The records of cases reported from southeast part of Turkey with suspected AFP between January 2007 and December 2019 were reviewed retrospectively.

RESULTS

Of the patients, 121 (58.5%) were male. Mean age was 80.36 ± 46.67 months. Eighty-five (41.1%) were aged 60 months or younger. The number of patients under 60 months increased significantly after 2011. Mean incidence was calculated as 0.88 cases/100,000 person years versus 1.58 cases/100,000 person years in the period before and after 2011, respectively. Guillain-Barré syndrome (GBS) was the most common cause of AFP in both periods. As of 2011, however, the incidence of acute transverse myelitis increased approximately 4 times and GBS decreased proportionally. Non-polio enteroviruses were the most frequent isolates, detected from 9.1% of stool samples.

CONCLUSION

Although refugee movements appear to may have adverse effects on AFP incidence and surveillance outcomes, larger studies involving the whole country, particularly at places where no refugees settled, are needed to achieve more conclusive evidence.

Incidence of Guillain-Barré syndrome in the world between 1985 and 2020: A systematic review

Introduction

Guillain-Barré syndrome (GBS) is an acute inflammatory demyelinating polyradiculoneuropathy that affects the peripheral nervous system. The study aimed to describe the incidence of GBS in the world up to the year 2020.

Methods

A systematic review was conducted. Searches were done in four databases, PUBMED, EMBASE, EBSCO and Biblioteca virtual em Saude (BVS), and in grey literature and manual search in the reference lists of eligible studies.

Results

A total of 72 studies were included. The incidence of GBS among the cohort studies varied from 0.30 to 6.08 cases per 100.000 habitants and 0.42 to 6.58 cases per 100.000 person-years. Among the self-controlled studies, the risk incidence ranged from 0.072 to 1 case per 100.000 habitants and 1.73 to 4.30 cases per 100.000 person-years.

Conclusions

The reported incidence of GBS in the world among the studies included in the review is slightly higher than that reported in previous studies. The highest incidence rates were associated with public health events of international concern.

Guillain-Barre syndrome: An autoimmune disorder post-COVID-19 vaccination?

SARS-CoV-2 causes Coronavirus Disease 2019 (COVID-19), an infectious condition that can present none or one or more of these symptoms: fever, cough, headache, sore throat, loss of taste and smell, aches, fatigue and musculoskeletal pain. For the prevention of COVID-19, there are vaccines available including those developed by Pfizer, Moderna, Sinovac, Janssen, and AstraZeneca. Recent evidence has shown that some COVID-19-vaccinated individuals can occasionally develop as a potential side effect Guillain-Barre syndrome (GBS), a severe neurological autoimmune condition in which the immune response against the peripheral nerve system (PNS) can result in significant morbidity. GBS had been linked previously to several viral or bacterial infections, and the finding of GBS after vaccination with certain COVID-19, while rare, should alert medical practitioners for an early diagnosis and targeted treatment. Here we review five cases of GBS that developed in different countries after COVID-19 vaccination.

National Surveillance for Acute Flaccid Myelitis - United States, 2018-2020

Acute flaccid myelitis (AFM), a recognized complication of certain viral infections, is a serious neurologic condition that predominantly affects previously healthy children and can progress rapidly, leading to respiratory insufficiency and permanent paralysis. After national AFM surveillance began in 2014, peaks in AFM cases were observed in the United States in 2014, 2016, and 2018 (1). On the basis of this biennial pattern, an increase in AFM was anticipated in 2020. To describe the epidemiology of confirmed AFM cases since 2018, demographic, clinical, and laboratory information collected as part of national AFM surveillance was reviewed. In 2018, a total of 238 confirmed AFM cases were reported to CDC, compared with 47 cases in 2019 and 32 in 2020. Enterovirus D68 (EV-D68) was detected in specimens from 37 cases reported in 2018, one case in 2019 and none in 2020. Compared with 2018, cases reported during 2019-2020 occurred in older children and were less frequently associated with upper limb involvement, febrile or respiratory prodromal illness, or cerebrospinal fluid (CSF) pleocytosis. These findings suggest that the etiologies of AFM in 2019 and 2020 differed from those in 2018. The absence of an increase in cases in 2020 reflects a deviation from the previously observed biennial pattern, and it is unclear when the next increase in AFM should be expected. Clinicians should continue to maintain vigilance and suspect AFM in any child with acute flaccid limb weakness, particularly in the setting of recent febrile or respiratory illness.

Molecular characterization and epidemiological aspects of non-polio enteroviruses isolated from acute flaccid paralysis in Brazil: a historical series (2005-2017)

Due to the advanced stage of polio eradication, the possible role of non-polio enteroviruses (NPEVs) associated to acute flaccid paralysis (AFP) cases has been highlighted. In this study, we described epidemiological aspects of NPEVs infections associated to AFP and explore the viral genetic diversity, information still scarce in Brazil. From 2005 to 2017, 6707 stool samples were collected in the scope of the Brazilian Poliomyelitis Surveillance Program. NPEVs were isolated in 359 samples (5.3%) and 341 (94.9%) were genotyped. About 46 different NPEV types were identified with the following detection pattern EV-B > EV-A > EV-C. The major EV-types were CVA2, CV4, EV-A71, CVB3, CVB5, E6, E7, E11, CVA13 and EV-C99, which corresponds to 51.6% of the total. Uncommon types, such as CVA12, EV-90 and CVA11, were also identified. Different E6 genogroups were observed, prevailing the GenIII, despite periods of co-circulation, and replacement of genogroups along time. CVA2 sequences were classified as genotype C and data suggested its dispersion in South-American countries. CVA13 viruses belonged to cluster B and Venezuelan viruses composed a new putative cluster. This study provides extensive information on enterovirus diversity associated with AFP, reinforcing the need of tailoring current surveillance strategies to timely monitor emergence/re-emergence of NPEVs.

Acute infectious myelopathies

PURPOSE OF REVIEW

The patient who presents with an acute spinal cord syndrome with weakness/paralysis of the limbs presents a diagnostic. Two important syndromes are acute transverse myelitis (ATM) and acute flaccid paralysis (AFP). Both can be caused by a number of infectious and noninfectious causes. Since 2014 there have been outbreaks of acute flaccid myelitis (a subgroup of AFP) in the United States, with a national surveillance program underway. In addition, there have been increasing reports of ATM from new and emerging pathogens, and opportunistic infections in immunocompromised hosts.

RECENT FINDINGS

Infectious causes of ATM or AFP need to be ruled out first. There may be important clues to an infectious cause from epidemiologic risk factors, immune status, international travel, MRI, and laboratory findings. We summarize key features for the more common pathogens in this review. Advances in laboratory testing have improved the diagnostic yield from cerebrospinal fluid, including real-time polymerase chain reaction, metagenomic next-generation sequencing, and advanced antibody detection techniques. These tests still have limitations and require clinical correlation.

SUMMARY

We present a syndromic approach to infectious myelopathies, focusing on clinical patterns that help narrow the diagnostic possibilities.

Characteristics of Patients with Acute Flaccid Myelitis, United States, 2015-2018

Differences between years with and without increased activity suggest differences in viral etiologies.

Observed peaks of acute flaccid myelitis (AFM) cases have occurred biennially since 2014 in the United States. We aimed to determine if AFM etiology differed between peak and nonpeak years, considering that clinical features of AFM differ by virus etiology. We compared clinical and laboratory characteristics of AFM cases that occurred during peak (2016 and 2018, n = 366) and nonpeak (2015 and 2017, n = 50) years. AFM patients in peak years were younger (5.2 years) than those in nonpeak years (8.3 years). A higher percentage of patients in peak years than nonpeak years had pleocytosis (86% vs. 60%), upper extremity involvement (33% vs. 16%), and an illness preceding limb weakness (90% vs. 62%) and were positive for enterovirus or rhinovirus RNA (38% vs. 16%). Enterovirus D68 infection was associated with AFM only in peak years. Our findings suggest AFM etiology differs between peak and nonpeak years.

Role of Melatonin on Virus-Induced Neuropathogenesis-A Concomitant Therapeutic Strategy to Understand SARS-CoV-2 Infection

Viral infections may cause neurological disorders by directly inducing oxidative stress and interrupting immune system function, both of which contribute to neuronal death. Several reports have described the neurological manifestations in Covid-19 patients where, in severe cases of the infection, brain inflammation and encephalitis are common. Recently, extensive research-based studies have revealed and acknowledged the clinical and preventive roles of melatonin in some viral diseases. Melatonin has been shown to have antiviral properties against several viral infections which are accompanied by neurological symptoms. The beneficial properties of melatonin relate to its properties as a potent antioxidant, anti-inflammatory, and immunoregulatory molecule and its neuroprotective effects. In this review, what is known about the therapeutic role of melatonin in virus-induced neuropathogenesis is summarized and discussed.

Neurological associations of COVID-19

BACKGROUND

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is of a scale not seen since the 1918 influenza pandemic. Although the predominant clinical presentation is with respiratory disease, neurological manifestations are being recognised increasingly. On the basis of knowledge of other coronaviruses, especially those that caused the severe acute respiratory syndrome and Middle East respiratory syndrome epidemics, cases of CNS and peripheral nervous system disease caused by SARS-CoV-2 might be expected to be rare.

RECENT DEVELOPMENTS

A growing number of case reports and series describe a wide array of neurological manifestations in 901 patients, but many have insufficient detail, reflecting the challenge of studying such patients. Encephalopathy has been reported for 93 patients in total, including 16 (7%) of 214 hospitalised patients with COVID-19 in Wuhan, China, and 40 (69%) of 58 patients in intensive care with COVID-19 in France. Encephalitis has been described in eight patients to date, and Guillain-Barré syndrome in 19 patients. SARS-CoV-2 has been detected in the CSF of some patients. Anosmia and ageusia are common, and can occur in the absence of other clinical features. Unexpectedly, acute cerebrovascular disease is also emerging as an important complication, with cohort studies reporting stroke in 2-6% of patients hospitalised with COVID-19. So far, 96 patients with stroke have been described, who frequently had vascular events in the context of a pro-inflammatory hypercoagulable state with elevated C-reactive protein, D-dimer, and ferritin. WHERE NEXT?: Careful clinical, diagnostic, and epidemiological studies are needed to help define the manifestations and burden of neurological disease caused by SARS-CoV-2. Precise case definitions must be used to distinguish non-specific complications of severe disease (eg, hypoxic encephalopathy and critical care neuropathy) from those caused directly or indirectly by the virus, including infectious, para-infectious, and post-infectious encephalitis, hypercoagulable states leading to stroke, and acute neuropathies such as Guillain-Barré syndrome. Recognition of neurological disease associated with SARS-CoV-2 in patients whose respiratory infection is mild or asymptomatic might prove challenging, especially if the primary COVID-19 illness occurred weeks earlier. The proportion of infections leading to neurological disease will probably remain small. However, these patients might be left with severe neurological sequelae. With so many people infected, the overall number of neurological patients, and their associated health burden and social and economic costs might be large. Health-care planners and policy makers must prepare for this eventuality, while the many ongoing studies investigating neurological associations increase our knowledge base.

Enterovirus D68-Associated Acute Flaccid Myelitis, United States, 2020

Acute flaccid myelitis (AFM) is a serious neurologic condition that causes limb weakness or paralysis in previously healthy children. Since clusters of cases were first reported in 2014, nationwide surveillance has demonstrated sharp increases in AFM cases in the United States every 2 years, most occurring during late summer and early fall. Given this current biennial pattern, another peak AFM season is expected during fall 2020 in the United States. Scientific understanding of the etiology and the factors driving the biennial increases in AFM has advanced rapidly in the past few years, although areas of uncertainty remain. The Centers for Disease Control and Prevention and AFM partners are focused on answering key questions about AFM epidemiology and mechanisms of disease. This article summarizes the current understanding of AFM etiology and outlines priorities for surveillance and research as we prepare for a likely surge in cases in 2020.

Vital Signs: Clinical Characteristics of Patients with Confirmed Acute Flaccid Myelitis, United States, 2018

Background

Acute flaccid myelitis (AFM) is a serious neurologic syndrome that affects mostly children and is characterized by the acute onset of limb weakness or paralysis. Since U.S. surveillance for AFM began in 2014, reported cases have peaked biennially. This report describes the clinical characteristics of AFM patients during 2018, the most recent peak year.

Methods

Medical records from persons meeting AFM clinical criterion (acute onset of flaccid limb weakness) were submitted to CDC. Patients with confirmed AFM met the clinical criterion and had magnetic resonance imaging indicating spinal cord lesions largely restricted to gray matter and spanning one or more vertebral segments. Symptoms, physical findings, test and imaging results, and hospitalization data were abstracted and described.

Results

Among 238 patients with confirmed AFM during 2018, median age was 5.3 years. Among the 238 patients, 205 (86%) had onset during August–November. Most (92%) had prodromal fever, respiratory illness, or both beginning a median of 6 days before weakness onset. In addition to weakness, common symptoms at clinical evaluation were gait difficulty (52%), neck or back pain (47%), fever (35%), and limb pain (34%). Among 211 who were outpatients when weakness began, most (76%) sought medical care within 1 day, and 64% first sought treatment at an emergency department. Overall, 98% of patients were hospitalized, 54% were admitted to an intensive care unit, and 23% required endotracheal intubation and mechanical ventilation.

Conclusion

Clinicians should suspect AFM in children with acute flaccid limb weakness, especially during August–November and when accompanied by neck or back pain and a recent history of febrile respiratory illness. Increasing awareness in frontline settings such as emergency departments should aid rapid recognition and hospitalization for AFM.

Enteroviruses in gastrointestinal diseases

Gastrointestinal diseases including diarrhoea constitute a major cause of morbidity and mortality in infants and young children especially in developing countries. Worldwide deaths among all ages due to diarrhoea during 2015 were estimated to be about 1.31 million, diarrhoeal deaths in children below 5 years of age being 499 000. Rotavirus accounted for about 200 000 deaths. Although diarrhoeal deaths decreased significantly during the last two decades, they still represent the third largest cause of infantile deaths. Several bacterial, viral, parasitic, fungal and non-infectious diarrhoea causing agents have been identified, but 30% to 40% of diarrhoeal cases remain undiagnosed. Enteroviruses transmit by the faecal-oral route and replicate first in intestinal cells before spreading to the target organ. They have been associated with diarrhoea in a few studies, but their causative role in diarrhoea in humans has not been systematically demonstrated. In view of the recent demonstration that enteroviruses cause diarrhoea in newborn mice pups, thus validating Koch's postulates, the purpose of this review is to emphasise the importance of recognising enteroviruses as major gastrointestinal pathogens associated with acute and persistent diarrhoea and non-diarrhoeal increased frequency of bowel movements in infants, young children and adults. Our studies and several other subsequent studies reported from different countries should stimulate strategies to reduce the burden of infantile gastrointestinal disease, which has hitherto remained unaddressed.

Molecular epidemiology of an enterovirus A71 outbreak associated with severe neurological disease, Spain, 2016

Introduction

Enterovirus A71 (EV-A71) is an emerging pathogen that causes a wide range of disorders including severe neurological manifestations. In the past 20 years, this virus has been associated with large outbreaks of hand, foot and mouth disease with neurological complications in the Asia-Pacific region, while in Europe mainly sporadic cases have been reported. In spring 2016, however, an EV-A71 outbreak associated with severe neurological cases was reported in Catalonia and spread further to other Spanish regions.

Aim

Our objective was to investigate the epidemiology and clinical characteristics of the outbreak.

Methods

We carried out a retrospective study which included 233 EV-A71-positive samples collected during 2016 from hospitalised patients. We analysed the clinical manifestations associated with EV-A71 infections and performed phylogenetic analyses of the 3’-VP1 and 3Dpol regions from all Spanish strains and a set of EV-A71 from other countries.

Results

Most EV-A71 infections were reported in children (mean age: 2.6 years) and the highest incidence was between May and July 2016 (83%). Most isolates (218/233) were classified as subgenogroup C1 and 217 of them were grouped in one cluster phylogenetically related to a new recombinant variant strain associated with severe neurological diseases in Germany and France in 2015 and 2016. Moreover, we found a clear association of EV-A71-C1 infection with severe neurological disorders, brainstem encephalitis being the most commonly reported.

Conclusion

An emerging recombinant variant of EV-A71-C1 was responsible for the large outbreak in 2016 in Spain that was associated with many severe neurological cases.

Coronaviruses and Central Nervous System Manifestations

SARS-CoV-2 is a highly pathogenic coronavirus that has caused an ongoing worldwide pandemic. Emerging in Wuhan, China in December 2019, the virus has spread rapidly around the world. Corona virus disease 2019 (COVID-19), which is caused by SARS-CoV-2, has resulted in significant morbidity and mortality. The most prominent symptoms of SARS-CoV-2 infection are respiratory. However, accumulating evidence highlights involvement of the central nervous system (CNS). This includes headache, anosmia, meningoencephalitis, acute ischemic stroke, and several presumably post/para-infectious syndromes and altered mental status not explained by respiratory etiologies. Interestingly, previous studies in animal models emphasized the neurotropism of coronaviruses; thus, these CNS manifestations of COVID-19 are not surprising. This minireview scans the literature regarding the involvement of the CNS in coronavirus infections in general, and in regard to the recent SARS-CoV-2, specifically.

Spectrum of Movement Disorders in Patients With Neuroinvasive West Nile Virus Infection

Background

West Nile virus (WNV) is a flavivirus that is recognized as one of the common causes of arboviral neurological disease in the world. WNV infections usually manifest with constitutional symptoms such as fever, fatigue, myalgia, rash, arthralgia, and headache. Neuroinvasive WNV infections are characterized by signs and symptoms suggestive of meningitis, encephalitis, meningoencephalitis, and acute flaccid paralysis. In addition, many patients with neuroinvasive WNV infection develop a wide range of movement disorders. This article aims to comprehensively review the spectrum and natural course of the movement disorders observed in patients with neuroinvasive WNV infections.

Methods

A literature search was performed in March 2019 (in PubMed and EMBASE) to identify articles for this review.

Results

Movement disorders observed in the context of WNV infections include tremor, opsoclonus-myoclonus, parkinsonism, myoclonus, ataxia, and chorea. Most often, these movement disorders resolve within a few weeks to months with an indolent course. The commonly observed tremor phenotypes include action tremor of the upper extremities (bilateral > unilateral). Tremor in patients with West Nile meningitis subsides earlier than that in patients with West Nile encephalitis/acute flaccid paralysis. Opsoclonus-myoclonus in WNV infections responds well to intravenous immunoglobulins/plasmapheresis/corticosteroids. Parkinsonism has been reported to be mild in nature and usually lasts for a few weeks to months in the majority of the patients.

Conclusion

A wide spectrum of movement disorders is observed in neuroinvasive WNV infections. Longitudinal studies are warranted to obtain better insights into the natural course of these movement disorders.

Genetic landscape and macro-evolution of co-circulating Coxsackieviruses A and Vaccine-derived Polioviruses in the Democratic Republic of Congo, 2008-2013

Enteroviruses (EVs) are among the most common viruses infecting humans worldwide but only a few Non-Polio Enterovirus (NPEV) isolates have been characterized in the Democratic Republic of Congo (DR Congo). Moreover, circulating vaccine-derived polioviruses (PVs) [cVDPVs] isolated during multiple outbreaks in DR Congo from 2004 to 2018 have been characterized so far only by the sequences of their VP1 capsid coding gene. This study was carried to i) investigate the circulation and genetic diversity of NPEV and polio vaccine isolates recovered from healthy children and Acute Flaccid Paralysis (AFP) patients, ii) evaluate the occurrence of genetic recombination among EVs belonging to the Enterovirus C species (including PVs) and iii) identify the virological factors favoring multiple emergences of cVDPVs in DR Congo. The biological material considered in this study included i) a collection of 91 Sabin-like PVs, 54 cVDPVs and 150 NPEVs isolated from AFP patients between 2008 and 2012 in DR Congo and iii) a collection of 330 stool specimens collected from healthy children in 2013 in the Kasai Oriental and Maniema provinces of DR Congo. Studied virus isolates were sequenced in four distinct sub-genomic regions 5’-UTR, VP1, 2C^ATPase and 3D^pol. Resulting sequences were compared through comparative phylogenetic analyses. Virus isolation showed that 19.1% (63/330) healthy children were infected by EVs including 17.9% (59/330) of NPEVs and 1.2% (4/330) of type 3 Sabin-like PVs. Only one EV-C type, EV-C99 was identified among the NPEV collection from AFP patients whereas 27.5% of the 69 NPEV isolates typed in healthy children belonged to the EV-C species: CV-A13 (13/69), A20 (5/69) and A17 (1/69). Interestingly, 50 of the 54 cVDPVs featured recombinant genomes containing exogenous sequences in at least one of the targeted non-structural regions of their genomes: 5’UTR, 2C^ATPase and 3D^pol. Some of these non-vaccine sequences of the recombinant cVDPVs were strikingly related to homologous sequences from co-circulating CV-A17 and A20 in the 2C^ATPase region as well as to those from co-circulating CV-A13, A17 and A20 in the 3D^pol region. This study provided the first evidence uncovering CV-A20 strains as major recombination partners of PVs. High quality AFP surveillance, sensitive environmental surveillance and efficient vaccination activities remain essential to ensure timely detection and efficient response to recombinant cVDPVs outbreaks in DR Congo. Such needs are valid for any epidemiological setting where high frequency and genetic diversity of Coxsackieviruses A13, A17 and A20 provide a conducive viral ecosystem for the emergence of virulent recombinant cVDPVs.

The strategy of the Global Polio Eradication Initiative is based on the surveillance of patients suffering from Acute Flaccid Paralysis (AFP) and mass vaccination with live-attenuated vaccine strains of polioviruses (PVs) in endemic areas. However, vaccine strains of PVs can circulate and replicate for a long time when the vaccine coverage of the population is low. Such prolonged circulation and replication of vaccine strains of PVs can result to the emergence of circulating vaccine-derived polioviruses [cVDPVs] that are as virulent as wild PVs. In this study, we performed the molecular characterization of a large collection of 377 virus isolates recovered from paralyzed patients between 2008 and 2012 in DR Congo and healthy children in 2013 in the Kasai Oriental and Maniema provinces of DR Congo. We found that the genetic diversity of enteroviruses of the species Enterovirus C is more important than previously reported. Interestingly, 50 of the 54 cVDPVs featured recombinant genomes containing exogenous sequences of the 2C ATPase and/or 3D polymerase coding genes acquired from co-circulating Coxsackieviruses A13, A17 and A20. Coxsackieviruses A20 strains were identified for the first time as major partners of genetic recombination with co-circulating live-attenuated polio vaccine strains.

Our findings highlight the need to reinforce and maintain high quality surveillance of PVs and efficient immunization activities in order to ensure early detection and control of emerging cVDPVs in all settings where high frequency and diversity of Coxsackieviruses A13, A17 and A20 have been documented.

Comparative quantitative clinical, neuroimaging, and functional profiles in children with acute flaccid myelitis at acute and convalescent stages of disease

AIM

To quantify characteristics in acute flaccid myelitis (AFM) at acute and convalescent stages.

METHOD

This was a retrospective case series of children with AFM evaluated at a single institution in the USA (2014-2017). Acute inflammatory/ischemic myelopathies were excluded. Neurological assessments and segmental quantitative analysis of signal abnormalities on magnetic resonance imaging (MRI) of the brain and spinal cord were performed.

RESULTS

Sixteen patients (11 males, five females) were evaluated. Median age at onset was 4 years (interquartile range [IQR] 3-6y). All had parainfectious acute-onset limb weakness, lower motor neuron examination, and spinal fluid pleocytosis. On acute spinal cord MRI, longitudinally extensive T2 hyperintensities were identified throughout the spinal cord mostly within grey matter; five out of 12 patients had dorsal brainstem T2 hyperintensities. At a median of 2 months follow-up (IQR 2-3mo), spinal cord MRI improved in seven out of nine patients although focal T2 hyperintensities persisted in cervical and lumbar grey matter. At a median follow-up of 4 months (IQR 2-6mo), Medical Research Council sum score rose from a median of 29 to 32; distal muscle groups improved more than proximal ones; four out of 16 patients were ventilator-dependent; and two out of 16 patients were quadriplegic.

INTERPRETATION

While patients may show marked improvement on neuroimaging from acute to convalescent stages, the majority of children with AFM have limited motor recovery and continued disability. Clinicians should consider the timing of clinical and neuroimaging exams when assessing diagnosis and prognosis.

WHAT THIS PAPER ADDS

During the 2014 to 2017 acute flaccid myelitis outbreak in the USA, clinical recovery was better in distal than proximal muscle groups. Lumbar spinal cord showed more residual abnormalities at convalescence.

Primary Epstein-Barr virus infection in immunocompetent patients with acute transverse myelitis and a combination of polyradiculitis and anterior horn syndrome as neurological manifestations

Neurological manifestations of a primary Epstein-Barr virus (EBV) infection are rare. We describe a case with acute transverse myelitis and another case with a combination of polyradiculitis and anterior horn syndrome as manifestations of a primary EBV infection.The first case is a 50-year-old immunocompetent male diagnosed with acute transverse myelitis, 2 weeks after he was clinically diagnosed with infectious mononucleosis. The second case is an 18-year-old immunocompetent male diagnosed with a combination of polyradiculitis and anterior horn syndrome while he had infectious mononucleosis. The first patient was treated with methylprednisolone. After 1 year, he was able to stop performing clean intermittent self-catheterisation. The second patient completely recovered within 6 weeks without treatment.Primary EBV infection should be considered in immunocompetent patients presenting with acute transverse myelitis and a combination of polyradiculitis and anterior horn syndrome. Antiviral treatment and steroids are controversial, and the prognosis of neurological sequelae is largely unknown.

Acute flaccid paralysis in South African children: Causes, respiratory complications and neurological outcome

AIM

To describe the causes, clinical presentation and neurological outcome of acute flaccid paralysis in children.

METHODS

A retrospective study in a tertiary paediatric hospital in South Africa. Data on clinical presentation, respiratory complications and long-term neurological outcomes of children presenting with acute flaccid paralysis were collected. Logistic regression analysis was applied to determine predictors for the need of mechanical ventilation.

RESULTS

The study included 119 patients, 99 of whom had Guillain-Barré syndrome (GBS); 47 patients (39.5%) required mechanical ventilation. Backward logistic regression analysis revealed that bulbar dysfunction (P < 0.001), autonomic dysfunction (P = 0.003) and upper limb paralysis (P = 0.038) significantly predicted the need for mechanical ventilation. EuroQol-5D scores of self-care problems and usual activities after discharge significantly declined over time.

CONCLUSIONS

In this large series from Africa, GBS was the main cause of acute flaccid paralysis in children and was associated with significant morbidity. Other causes of acute flaccid paralysis mimicking GBS were not uncommon and should be excluded in this setting.

Non-polio Enterovirus detection with acute flaccid paralysis: A systematic review

Acute flaccid paralysis (AFP), as defined by the World Health Organization (WHO), is characterized by an acute onset of limb weakness. In the post-polio era, other enterovirus (EV) serotypes associated with AFP may become more prominent. This study aims to collate the data on the non-polio enteroviruses (NPEV) associated with AFP. A systematic review of published case reports, case series, and surveillance studies of AFP from 1960 through 2017 was undertaken. Data were collected including the country of the study, number of specimens positive for NPEV and available clinical data. The majority of studies originated from Asia. In surveillance studies, EV 71 (a serotype of Enterovirus A) was the most commonly detected serotype with AFP, followed by Enterovirus B serotype echovirus 11 and then Enterovirus B serotype echovirus 11. In case studies and case reports, EV 71 and EV 68 (a serotype of Enterovirus D), were the most commonly detected NPEV. As poliovirus eradication continues, there is a need to ensure that AFP surveillance will also detect other potentially vaccine preventable viruses.

Clinical Characteristics of Severe Japanese Encephalitis: A Case Series from South Korea

Japanese encephalitis (JE) virus is a major cause of devastating viral encephalitis, especially in Asia. Although a successful vaccination program led to its near-elimination over three decades in South Korea, the incidence of JE has increased since 2010. The present study investigated the clinical manifestations, laboratory findings, and factors affecting neurological outcomes of reemerging JE. We retrospectively reviewed medical records of laboratory-confirmed JE patients who presented with acute encephalitis syndrome at three tertiary hospitals between 2010 and 2015. A total of 17 patients with JE were identified. Their median age was 51 years, and 10 (58.5%) were men. The most common symptoms and signs were fever (94.1%), altered consciousness (94.1%), and headache (80.2%). Hyporeflexia (47.1%), seizures (35.2%), abnormal brainstem reflex (23.5%), and flaccid weakness (17.6%) were also noted. Brain imaging revealed thalamic lesions in all patients, with the hippocampus, midbrain, basal ganglia, and cerebral cortex affected to varying degrees. Sixteen patients (94.1%) required management in the intensive care unit with mechanical ventilation due to neurological deterioration. At the time of discharge, 11 (64.7%) had poor recovery, defined as Glasgow coma scale scores of less than 8, and remained ventilator dependent. Comparison between the two outcome groups indicated that midbrain involvement (P = 0.028) and rapid deterioration (P = 0.005) were associated with severe neurological sequelae. Given that JE is a vaccine-preventable disease, vaccination for adults should be considered in response to the reemergence of JE.

Spinal Cord Infarction in the Course of a Septic Shock: About One Case and Review of the Literature

We report the case of a patient admitted to our intensive care unit in the course of a septic shock, secondary to cholangitis. After rapid hemodynamic stabilization, antibiotherapy, and endoscopic extraction of bile ducts stones, she appeared to have developed flaccid paraplegia. The suspected diagnosis of medullar ischemia was confirmed by typical MRI findings. This case stresses the potential pathogenic role of hypotension in medullar ischemia and the place of magnetic resonance imaging (MRI) as a reliable diagnostic tool.

Acute Flaccid Myelitis in the United States, August-December 2014: Results of Nationwide Surveillance

BACKGROUND

During late summer/fall 2014, pediatric cases of acute flaccid myelitis (AFM) occurred in the United States, coincident with a national outbreak of enterovirus D68 (EV-D68)-associated severe respiratory illness.

METHODS

Clinicians and health departments reported standardized clinical, epidemiologic, and radiologic information on AFM cases to the Centers for Disease Control and Prevention (CDC), and submitted biological samples for testing. Cases were ≤21 years old, with acute onset of limb weakness 1 August-31 December 2014 and spinal magnetic resonance imaging (MRI) showing lesions predominantly restricted to gray matter.

RESULTS

From August through December 2014, 120 AFM cases were reported from 34 states. Median age was 7.1 years (interquartile range, 4.8-12.1 years); 59% were male. Most experienced respiratory (81%) or febrile (64%) illness before limb weakness onset. MRI abnormalities were predominantly in the cervical spinal cord (103/118). All but 1 case was hospitalized; none died. Cerebrospinal fluid (CSF) pleocytosis (>5 white blood cells/µL) was common (81%). At CDC, 1 CSF specimen was positive for EV-D68 and Epstein-Barr virus by real-time polymerase chain reaction, although the specimen had >3000 red blood cells/µL. The most common virus detected in upper respiratory tract specimens was EV-D68 (from 20%, and 47% with specimen collected ≤7 days from respiratory illness/fever onset). Continued surveillance in 2015 identified 16 AFM cases reported from 13 states.

CONCLUSIONS

Epidemiologic data suggest this AFM cluster was likely associated with the large outbreak of EV-D68-associated respiratory illness, although direct laboratory evidence linking AFM with EV-D68 remains inconclusive. Continued surveillance will help define the incidence, epidemiology, and etiology of AFM.

A rare cause of acute flaccid paralysis: Human coronaviruses

Acute flaccid paralysis (AFP) is a life-threatening clinical entity characterized by weakness in the whole body muscles often accompanied by respiratory and bulbar paralysis. The most common cause is Gullian–Barre syndrome, but infections, spinal cord diseases, neuromuscular diseases such as myasthenia gravis, drugs and toxins, periodic hypokalemic paralysis, electrolyte disturbances, and botulism should be considered as in the differential diagnosis. Human coronaviruses (HCoVs) cause common cold, upper and lower respiratory tract disease, but in the literature presentation with the lower respiratory tract infection and AFP has not been reported previously. In this study, pediatric case admitted with lower respiratory tract infection and AFP, who detected for HCoV 229E and OC43 co-infection by the real-time polymerase chain reaction, has been reported for the first time.

Spinal Nerve Root Enhancement on MRI Scans in Children: A Review

Spinal nerve root enhancement in pediatric patients is generally nonspecific, and clinical and laboratory correlation is essential. Nerve root enhancement indicates lack of integrity of the blood-nerve barrier. In this review, we will present a range of pediatric conditions that can present with spinal nerve root enhancement including inflammatory, infectious, hereditary, and neoplastic causes. Familiarity with the various pathologic entities associated with spinal nerve root enhancement is important for a concise differential diagnosis in the appropriate clinical setting. This will avoid unnecessary additional investigations.

The first reported case of West Nile encephalitis in Korea

West Nile encephalitis was first identified in 1937, but until now, it was never diagnosed in Korea. A 58-yr-old Korean man was admitted with headache and cognitive dysfunction. The patient had been on a business trip in Guinea. Cerebrospinal fluid (CSF) showed pleocytosis. The patient complained of both leg weakness,and arachnoiditis and myelitis were observed on lumbar magnetic resonance imaging (MRI). A specific neutralizing antibody for West Nile virus was positive in serum. After a treatment with interferon-α 3mu, follow up CSF findings recovered completely after 3 months later. The first case of West Nile encephalitis in Korea was imported from Guinea, and was cured successfully.

High frequency of enterovirus D68 in children hospitalised with respiratory illness in Norway, autumn 2014

Objectives

An unexpectedly high proportion of children were admitted for severe respiratory infections at the Oslo University Hospital, Ullevål, Norway, during September and October, 2014. In light of the ongoing outbreak of enterovirus-D68 (EV-D68) in North America a real-time RT-PCR for screening of enterovirus and enterovirus D68 was established.

Design

We developed a duplex real-time RT-PCR for rapid screening of enterovirus D68. The method target the 5′ non-translated region (NTR) of the HEV genome at a location generally used for enterovirus detection.

Sample

Nasopharyngeal samples (n = 354), from children <15 years of age, received for respiratory virus analysis in OUH during September 1st and October 31nd, 2014, were tested for enterovirus and screened for enterovirus D68.

Main outcome measures and results

The duplex real-time RT-PCR method was an efficient tool for rapid screening for EV-D68 in respiratory specimens. Enterovirus was detected in 66 (22%) of 303 pediatric nasopharyngeal samples collected from children hospitalised with acute respiratory infection within the two-month period. Out of these, 33 (50%) were EV-D68. EV-D68 was associated with acute flaccid paralysis in one child.

Conclusions

An unexpectedly high proportion of children admitted for severe respiratory infections at the Oslo University Hospital, Ullevål, Norway, were diagnosed with EV- D68 during September 1st and October 31nd, 2014. These results emphasise that greater vigilance is required throughout Europe as enteroviruses are cause of severe respiratory disease.

Molecular epidemiology of enterovirus B77 isolated from non polio acute flaccid paralytic patients in Pakistan during 2013

Human enteroviruses are associated with various clinical syndromes and severe neurological disorders. The aim of this study was to determine the molecular epidemiology of non polio enteroviruses and their correlation with acute flaccid paralysis (AFP) patients living in Khyber Pakhtunkhwa (KP) and Federally Administered Tribal Areas (FATA) of Pakistan. The stool samples collected from these patients were used for isolation of non polio enteroviruses (NPEVs). Out of 38 samples, 29 (76.3%) were successfully typed by microneutralization assay into eleven serotypes including echovirus (E)-3 (5.3%), E-7 (2.6%), E-11 (13.2%), E-12 (7.9%), E-13 (10.5%), E-20 (7.9%), E-27 (5.3%), E-29 (10.5%), E-30 (7.9%), E-33 (2.6%), coxsackievirus (CV) B5 (2.6%) and nine isolates (23.7%) remained untyped which were confirmed as NPEVs by real time RT-PCR. Complete VP1 genetic sequencing data characterized untypeable isolates into enterovirus B77 (EV-B77). Moreover, molecular phylogenetic analysis classified these viruses into two new genotypes having high genetic diversity (at least 17.7%) with prototype. This study provides valuable information on extensive genetic diversity of EV-B77 genotypes. Although, its association with neurological disorder has not yet been known but isolation of nine EV-B77 viruses from AFP cases highlights the fact that they may have a contributing role in the etiology of AFP. In addition, it is needed to establish enterovirus surveillance system and laboratory diagnostic facilities for early detection of NPEVs that may cause poliomyelitis like paralysis especially in the situation when we are at the verge of polio eradication.

Neuroepidemiology and the epidemiology of viral infections of the nervous system

The field of neurovirology will undoubtedly experience evolution and change in the years to come. The epidemiology of viral CNS diseases continues to change, and as our understanding of the pathogenesis and pathophysiology associated with viral agents grows, so does our understanding of the behavior of these pathogens among populations. The appearance of viral pathogens in newsettings, new or unrecognized modes of transmission,and the emergence of previously unrecognized pathogens will continue to challenge our laboratory diagnostic and epidemiologic capabilities. However, each lesson that is learned from this evolving epidemiology will hopefully result in improved surveillance, diagnostic,and treatment and prevention capabilities.

Fifteen years of acute flaccid paralysis surveillance in Hong Kong: findings from 1997 to 2011

AIM

Acute flaccid paralysis (AFP) surveillance system was set up in Hong Kong in 1997 for World Health Organization's (WHO) certification of poliomyelitis eradication. This paper describes and reviews the demographic, clinical and virological characteristics of AFP cases reported to the system in its first 15 years.

METHODS

All patients aged under 15 years presented with acute onset of paralysis of any limbs reported to the Department of Health from January 1997 to December 2011 were reviewed. Data on demographic characteristics, vaccination history, clinical presentation and virological investigation on stool specimens collected during investigation were analysed with descriptive statistics.

RESULTS

Of the 247 cases reported, about 45% were aged under five. All cases were classified as non-polio AFP according to WHO classification. About 60% were identified with neurological disorders, with Guillain-Barré syndrome (25.9%) and myelitis (13.4%) being the most common. Viruses were detected in 14.0% of the AFP cases, with non-polio enteroviruses (NPEV) (60.0%) and adenoviruses (31.4%) accounted for most of the positive detections. Most performance indicators set by the WHO were fulfilled.

CONCLUSIONS

The AFP surveillance facilitated the clinical, virological and epidemiological examination of paediatric AFP cases. From 1997 to 2011, Guillain-Barré syndrome and myelitis were the most common among paediatric AFP cases in Hong Kong. NPEV and adenoviruses accounted for most of the positive viral detections. No wild poliovirus was detected, and all cases were classified as non-polio AFP.

Viral Aetiology of Acute Flaccid Paralysis Surveillance Cases, before and after Vaccine Policy Change from Oral Polio Vaccine to Inactivated Polio Vaccine

Since 1992, surveillance for acute flaccid paralysis (AFP) cases was introduced in Malaysia along with the establishment of the National Poliovirus Laboratory at the Institute for Medical Research. In 2008, the Ministry of Health, Malaysia, approved a vaccine policy change from oral polio vaccine to inactivated polio vaccine (IPV). Eight states started using IPV in the Expanded Immunization Programme, followed by the remaining states in January 2010. The objective of this study was to determine the viral aetiology of AFP cases below 15 years of age, before and after vaccine policy change from oral polio vaccine to inactivated polio vaccine. One hundred and seventy-nine enteroviruses were isolated from the 3394 stool specimens investigated between 1992 and December 2012. Fifty-six out of 107 virus isolates were polioviruses and the remaining were non-polio enteroviruses. Since 2009 after the sequential introduction of IPV in the childhood immunization programme, no Sabin polioviruses were isolated from AFP cases. In 2012, the laboratory AFP surveillance was supplemented with environmental surveillance with sewage sampling. Thirteen Sabin polioviruses were also isolated from sewage in the same year, but no vaccine-derived poliovirus was detected during this period.

Clinical manifestations and outcomes of West Nile virus infection

Since the emergence of West Nile virus (WNV) in North America in 1999, understanding of the clinical features, spectrum of illness and eventual functional outcomes of human illness has increased tremendously. Most human infections with WNV remain clinically silent. Among those persons developing symptomatic illness, most develop a self-limited febrile illness. More severe illness with WNV (West Nile neuroinvasive disease, WNND) is manifested as meningitis, encephalitis or an acute anterior (polio) myelitis. These manifestations are generally more prevalent in older persons or those with immunosuppression. In the future, a more thorough understanding of the long-term physical, cognitive and functional outcomes of persons recovering from WNV illness will be important in understanding the overall illness burden.

Characterization of the non-polio enterovirus infections associated with acute flaccid paralysis in South-Western India

Non-polio enteroviruses (NPEVs) have been reported frequently in association with acute flaccid paralysis (AFP) cases during Polio Surveillance Programs (PSPs) worldwide. However, there is limited understanding on the attributes of their infections. This study reports characteristics of NPEVs isolated from AFP cases, investigated during PSPs held in 2009-2010, in Karnataka and Kerala states of south-western India having varied climatic conditions. NPEV cell culture isolates derived from stool specimens that were collected from 422 of 2186 AFP cases (<1-14 years age) and 17 of 41 asymptomatic contacts; and details of all AFP cases/contacts were obtained from National Polio Laboratory, Bangalore. The distribution of NPEV infections among AFP cases and circulation pattern of NPEV strains were determined by statistical analysis of the data. Genotyping of all NPEV isolates was carried out by partial VP1 gene sequencing and phylogenetic analysis. NPEV positive AFP cases were significantly higher in children aged <2 years; with residual paralysis; in summer months; and in regions with relatively hot climate. Genotyping of NPEVs identified predominance of human enteroviruses (HEV)-B species [81.9%-Echoviruses (E): 57.3%; coxsackieviruses (CV) B: 15%; numbered EVs: 8.9%; CVA9: 0.7%] and low levels of HEV-A [14.5%-CVA: 6%; numbered EVs: 8.5%] and HEV-C [3.6%-CVA: 2.6%; numbered EVs: 1%] species, encompassing 63 genotypes. EV76 (6.3%) and each of E3, CVB3 and E9 (4.97%) were found frequently during 2009 while E11 (6.7%), CVB1 (6.1%), E7 (5.1%) and E20 (5.1%) were detected commonly in 2010. A marked proportion of AFP cases from children aged <2 years; presenting with fever; and from north and south interior parts of Karnataka state was detected with E/numbered EVs than that found with CVA/CVB. This study highlights the extensive genetic diversity and diverse circulation patterns of NPEV strains in AFP cases from different populations and climatic conditions.

Antigenic diversity of enteroviruses associated with nonpolio acute flaccid paralysis, India, 2007-2009

Because of the broadened acute flacid paralysis (AFP) definition and enhanced surveillance, many nonpolio AFP (NP-AFP) cases have been reported in India since 2005. To determine the spectrum of nonpolio enterovirus (NPEV) serotypes associated with NP-AFP from polio-endemic and -free regions, we studied antigenic diversity of AFP-associated NPEVs. Of fecal specimens from 2,786 children with NP-AFP in 1 polio-endemic and 2 polio-free states, 823 (29.5%) were positive for NPEVs in RD cells, of which 532 (64.6%) were positive by viral protein 1 reverse transcription PCR. We identified 66 serotypes among 581 isolates, with enterovirus 71 most frequently (8.43%) detected, followed by enterovirus 13 (7.1%) and coxsackievirus B5 (5.0%). Most strains within a serotype represented new genogropups or subgenogroups. Agents for ≈35.0% and 70.0% of culture-positive and -negative cases, respectively, need to be identified. Association of human enterovirus with NP-AFP requires better assessment and understanding of health risks of NPEV infections after polio elimination.

The Pathogenesis and Prevention of Encephalitis due to Human Enterovirus 71

Human enterovirus 71 (HEV71) has emerged as a major cause of viral encephalitis in Southeast Asia, with increased epidemic activity observed since 1997. This is reflected in a large increase in scientific publications relating directly to HEV71. New research is elucidating details of the viral life cycle, confirming similarities between HEV71 and other enteroviruses. Scavenger receptor B2 (SCARB2) is a receptor for HEV71, although other receptors are likely to be identified. Currently, the only strategies to prevent HEV71-associated disease are early diagnosis and aggressive supportive management of identified cases. As more information emerges regarding the molecular processes of HEV71 infection, further advances may lead to the development of effective antiviral treatments and ultimately a vaccine-protection strategy. The protective efficacies of several inactivated HEV71 vaccines have been confirmed in animal models, suggesting that an effective vaccine may become available in the next decade.

Neurologic symptoms associated with cattle farming in the agricultural health study

OBJECTIVE

Infection with Campylobacter jejuni, a bacterium carried by poultry and livestock, is the most frequently identified antecedent to the autoimmune neurologic condition Guillain-Barré Syndrome. We used Agricultural Health Study data to assess whether cattle farming was associated with prevalence of neurologic symptoms.

METHODS

Prevalence of self-reported symptoms in cattle farmers (n = 8878) was compared with farmers who did not work with animals (n = 7462), using multivariate regression.

RESULTS

Prevalence of numbness and weakness were increased for beef and dairy farmers compared with the reference group (P < 0.0001). Of cattle farmers, 48% did not report raising other animal species, and prevalence of numbness and weakness were also increased in this subgroup compared with the reference group (P < 0.02).

CONCLUSIONS

Occupational exposure to cattle was associated with increased prevalence of self-reported symptoms associated with peripheral neuropathy.

Recent advances in the molecular epidemiology and control of human enterovirus 71 infection

Human enterovirus 71 (HEV71) has emerged as an important cause of viral encephalitis in the Southeast Asia over the past 15 years. A pattern of increased epidemic activity and endemic circulation of HEV71 has been observed since 1997 and is associated with the regular emergence of new genetic lineages. Although the reason for this increase in HEV71 circulation remains unknown, evidence is accumulating that recombination events may drive the evolution of new genetic lineages. Prevention of HEV71 epidemics is likely to require the development of an effective vaccine. Fortunately, several candidate EV71 vaccines have recently been reported, several of which have been shown to be effective in animal models and commenced clinical trial in 2010. Furthermore, ongoing investigations into the molecular basis of HEV71 infection and virulence have pointed the way towards novel approaches to live attenuated vaccine development.

Neuroimaging in acute transverse myelitis

Transverse myelitis is an acute inflammatory condition. A relatively rare condition, the diversity of causes makes it an important diagnostic challenge. An approach to the classification and work-up standardizes diagnostic criteria and terminology to facilitate clinical research, and forms a useful tool in the clinical work-up for patients at presentation. Its pathogenesis can be grouped into four categories. Imaging appearances can be nonspecific; however, the morphology of cord involvement, enhancement pattern, and presence of coexistent abnormalities on MR imaging can provide clues as to the causes. Neuroimaging is important in identifying subgroups that may benefit from specific treatment.

Formalin-inactivated vaccine provokes cross-protective immunity in a mouse model of human enterovirus 71 infection

Human enterovirus 71 (HEV71) has emerged as a major cause of epidemics of hand, foot and mouth disease associated with severe neurological sequelae in the Asia-Pacific region. In this study, a passive protection mouse model was used to evaluate the protective efficacy of formalin-inactivated HEV71 vaccines derived from a Chinese C4 genotype strain. Pregnant mice were immunised using a prime/boost strategy and ≥50U of vaccine protected five-day-old pups from lethal challenge with a mouse-adapted (B3 genotype) strain of HEV71. Immunised mice developed a neutralising antibody response to both the immunising C4 strain and to the mouse-adapted strain. Mice born to immunised dams showed significantly less myositis and reduced viral loads in tissues.

Guillain-Barré syndrome as a prominent cause of childhood acute flaccid paralysis in post polio eradication era in Egypt

Guillain-Barré syndrome often follows an antecedent gastrointestinal or respiratory illness but, in rare cases, follows vaccination. This study was conducted to identify preceding events, demographic, clinical characteristics and prognostic factors of childhood Guillain-Barré syndrome after post-poliomyelitis eradication era in Egypt. This is a prospective study of all children with GBS (no = 50) admitted to pediatric Cairo University Hospital between January 2006 and June 2007 (70.42% of all acute flaccid paralysis patients during this period). Upper respiratory infection was the most common preceding event (24%) while only 4 patients (8%) reported antecedent oral polio vaccine. Motor deficit was frequent and severe (quadriparesis in 92% and paraparesis in 8%). Autonomic dysfunction was recorded in 32% of patients. Forty two percent of patients had poor outcome with 16% deaths. Presence of severe disability on admission and on nadir, cranial nerve affection or the need for mechanical ventilator were found to be significant predictors for poor outcome.

Enterovirus infections of the central nervous system

Enteroviruses (EV) frequently infect the central nervous system (CNS) and induce neurological diseases. Although the CNS is composed of many different cell types, the spectrum of tropism for each EV is considerable. These viruses have the ability to completely shut down host translational machinery and are considered highly cytolytic, thereby causing cytopathic effects. Hence, CNS dysfunction following EV infection of neuronal or glial cells might be expected. Perhaps unexpectedly given their cytolytic nature, EVs may establish a persistent infection within the CNS, and the lasting effects on the host might be significant with unanticipated consequences. This review will describe the clinical aspects of EV-mediated disease, mechanisms of disease, determinants of tropism, immune activation within the CNS, and potential treatment regimes.

Interleukin-4 regulates the expression of CD209 and subsequent uptake of Mycobacterium leprae by Schwann cells in human leprosy

The ability of microbial pathogens to target specific cell types is a key aspect of the pathogenesis of infectious disease. Mycobacterium leprae, by infecting Schwann cells, contributes to nerve injury in patients with leprosy. Here, we investigated mechanisms of host-pathogen interaction in the peripheral nerve lesions of leprosy. We found that the expression of the C-type lectin, CD209, known to be expressed on tissue macrophages and to mediate the uptake of M. leprae, was present on Schwann cells, colocalizing with the Schwann cell marker, CNPase (2',3'-cyclic nucleotide 3'-phosphodiesterase), along with the M. leprae antigen PGL-1 in the peripheral nerve biopsy specimens. In vitro, human CD209-positive Schwann cells, both from primary cultures and a long-term line, have a higher binding of M. leprae compared to CD209-negative Schwann cells. Interleukin-4, known to be expressed in skin lesions from multibacillary patients, increased CD209 expression on human Schwann cells and subsequent Schwann cell binding to M. leprae, whereas Th1 cytokines did not induce CD209 expression on these cells. Therefore, the regulated expression of CD209 represents a common mechanism by which Schwann cells and macrophages bind and take up M. leprae, contributing to the pathogenesis of leprosy.