Neurologic complications in children with enterovirus 71 infection

Enterovirus 71, one virus and many stories

Enterovirus 71 (EV71) has emerged as a significant cause of brainstem encephalitis and acute flaccid paralysis in Taiwan. It may be complicated by autonomic nervous system dysregulation and pulmonary edema (PE). Cytokines in the central nervous system and systemic inflammatory responses play important roles in the pathogenesis of EV71-associated PE. Pathogenesis-based management with intravenous immunoglobulin and milrinone has been associated with reduced mortality in children with severe EV71 infections.

Enterovirus 71 in Taiwan

The enterovirus 71 (EV71) outbreak in Taiwan in 1998 proved fatal in many children. A seroepidemiological study performed prior to the 1998 outbreak showed pre-epidemic (1997) EV71 seroprevalence rates to be about 60-70% in adults and children older than 6 years of age. A retrospective case review carried out from 1980-81 identified 16 cases of hand, foot and mouth disease associated with central nervous system involvement, two of whom died soon after hospitalization. There were 405 severe cases and 78 deaths reported in the 1998 epidemic, and dozens of fatal EV71 cases were still reported from 2000 to 2002. A stage-based management strategy was developed to reduce fatality, but most survivors of brainstem encephalitis with cardiopulmonary failure have neurologic sequelae and impaired cognition. Continuous clinical and laboratory surveillance of EV71 disease is required to enable earlier implementation of control and prevention measures. Development of EV71-specific antiviral therapy, a novel class of imidazolidinones, and development of a vaccine are ongoing.

Emerging issues in neurovirology: new viruses, diagnostic tools, and therapeutics

In the current era of escalating globalization with rapid transport, changing climate, and an ever growing human population with associated changes in lifestyle, poverty, and war, the emergence of new neurologic infections is accelerated. Understanding their origins using epidemiologic and molecular tools will contribute to improved control of agent spread throughout vulnerable populations. Although few interventions are effective in acute epidemics, the prompt identification of new infectious agents and the roll-out of vaccines together with new antiviral and neuroprotective drugs are promising for the management of future epidemics.

Acute encephalitis caused by intrafamilial transmission of enterovirus 71 in adult

Enterovirus 71 (EV71) is a common cause of hand, foot, and mouth disease and sometimes causes severe neurologic complications, mainly in children. We report a case of adult-onset encephalitis caused by intrafamilial transmission of a subgenogroup C4 strain of EV71. This case elucidates the risk for EV71 encephalitis even in adults.

Neuroimaging of viral infections in infants and young children

Many viral infections can involve the central nervous systems (CNS) of fetuses, neonates, infants, and children. The pathogenesis, patterns of CNS involvement, and species of viral infection may differ in the developing fetus, infant and neonate, and early childhood. Familiarity with the clinical course and imaging appearances of the variable CNS diseases is helpful in making correct differential diagnoses and in prompting timely treatment. This article reviews the clinical courses, pathologic findings, and imaging features of the most common viral infections that may involve the CNS of neonates and infants, including congenital and neonatal CNS viral infections, common CNS viral infections, and parainfectious encephalomyelitis.

Expression of VP1 protein in the milk of transgenic mice: a potential oral vaccine protects against enterovirus 71 infection

Enterovirus 71 (EV71) is the most common etiological agent detected in cases of hand-foot-and-mouth disease (HFMD) resulting in incidences of neurological complications and fatality in recent years. The clinical data have already shown the significant increase in recent EV71 epidemic activity throughout the Asia-Pacific region. Due to the lack of an effective antiviral agent, primary prevention of the disease, including the development of an effective vaccine, has been the top priority in terms of control strategies. In this study, we first generated a transgenic animal system to produce the EV71 VP1 capsid protein under the control of alpha-lactalbumin promoter and alpha-casein leader sequences. A high level of recombinant VP1 protein (2.51 mg/ml) was expressed and secreted into the milk of transgenic mice. Mouse pups that received VP1-transgenic milk orally demonstrated relatively better health conditions after challenge with the respective virus as compared with the non-transgenic milk fed group; moreover, the mice fed with the VP1-milk had body weights similar to those of the PBS placebo control groups. According to the serum-neutralization assay and serum antibody detection, the littermates suckling VP1-milk generated antibodies specific to EV71. Our data suggest that EV71 VP1-containing milk is suitable for development as a potential oral vaccine.

Upper aerodigestive tract sequelae in severe enterovirus 71 infection: predictors and outcome

OBJECTIVE

Enterovirus 71 (EV71) infection sequelae can be severe and life-threatening, and long-term follow-up outcomes remain unknown. Therefore, we conducted a retrospective follow-up study to review airway and neurological sequelae development in patients with severe EV71 infection. We also studied the incidence and risk factors for tracheotomy and gastrostomy requirement.

PATIENTS AND METHODS

We investigated 202 EV71-infected children according to their disease stage. Seventy-two of them were diagnosed to have EV71 encephalitis, which was characterized by myoclonus, ataxia, nystagmus, oculomotor palsy and bulbar palsy or combinations of these conditions. All the 72 patients required endotracheal intubation due to respiratory failure or ventilator dependence; among these, 14 underwent tracheostomy and 10 underwent gastrostomy. All patients were followed-up for at least 3 years after discharge. Predictors of tracheostomy and gastrostomy requirement were age <2 years, body weight <10th percentile, pulmonary hemorrhage or edema, meningeal symptoms and magnetic resonance imaging (MRI) findings of upper spinal cord and brainstem. We determined outcome based on persistent tracheostomy or gastrostomy requirement and whether patients developed positive neurological sequelae.

RESULTS

Significant tracheostomy and gastrostomy predictors were age <2 years, pulmonary edema or hemorrhage, hypotension, hemiparesis and positive MRI findings. Statistical analysis revealed pulmonary edema and hypotension as index predictors of tracheostomy requirement and pulmonary edema as the significant risk factor for gastrostomy.

CONCLUSIONS

Long-term neuropsychological impact was observed on children who present the signs of the pulmonary edema or hypotension in the early onset of the EV71 infection. EV71-infected patients who develop neurological pulmonary edema or hypotension should be hemodynamically stabilized and undergo early tracheostomy to prevent further complications. This may improve the decannulation success rate after the brainstem function recovers.

Cooperative effect of the attenuation determinants derived from poliovirus sabin 1 strain is essential for attenuation of enterovirus 71 in the NOD/SCID mouse infection model

Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and is also associated with serious neurological disorders. An attenuated EV71 strain [EV71(S1-3')] has been established in the cynomolgus monkey infection model; this strain contains the attenuation determinants derived from the type 1 poliovirus vaccine strain, Sabin 1 [PV1(Sabin)], in the 5' nontranslated region (NTR), 3D polymerase, and 3' NTR. In this study, we analyzed the effect of the attenuation determinants of PV1(Sabin) on EV71 infection in a NOD/SCID mouse infection model. We isolated a mouse-adapted EV71 strain [EV71(NOD/SCID)] that causes paralysis of the hind limbs in 3- to 4-week-old NOD/SCID mice by adaptation of the virulent EV71(Nagoya) strain in the brains of NOD/SCID mice. A single mutation at nucleotide 2876 that caused an amino acid change in capsid protein VP1 (change of the glycine at position 145 to glutamic acid) was essential for the mouse-adapted phenotype in NOD/SCID mice. Next, we introduced attenuation determinants derived from PV1(Sabin) along with the mouse adaptation mutation into the EV71(Nagoya) genome. In 4-week-old mice, the determinants in the 3D polymerase and 3' NTR, which are the major temperature-sensitive determinants, had a strong effect on attenuation. In contrast, the effect of individual determinants was weak in 3-week-old NOD/SCID mice, and all the determinants were required for substantial attenuation. These results suggest that a cooperative effect of the attenuation determinants of PV1(Sabin) is essential for attenuated neurovirulence of EV71.

Hand, foot and mouth disease complicated with central nervous system involvement in Taiwan in 1980-1981

Sixteen cases from the 1980-1981 Taiwan outbreak of hand, foot and mouth disease (HFMD) associated with central nervous system involvement were identified: nine had polio-like syndrome, four had encephalitis or encephalomyelitis, one had cerebellitis, and two had aseptic meningitis. They all had fever, five (31%) had documented myoclonic jerk, and 15 (93%) had HFMD. Their mean blood leukocyte count was 12,490/microL, and five (31%) had leukocytosis (> 15,000/microL); mean cerebrospinal fluid (CSF) leukocyte count was 156/microL, CSF protein was 57 mg/dL and CSF glucose was 57 mg/dL. Two patients with HFMD plus encephalitis died within 1 day of hospitalization, and one of them had acute cardiopulmonary failure mimicking myocarditis. Twenty years later, at least one male patient had sequelae of polio-like syndrome and was therefore exempted from military service. Clinical severity was comparable to the 1998 EV71 epidemic.

Enterovirus 71 triggering of neuronal apoptosis through activation of Abl-Cdk5 signalling

The molecular mechanism behind what causes an infection of Enterovirus 71 (EV71) in young children to result in severe neurological diseases is unclear. Herein, we show that Cdk5, a critical signalling effector of various neurotoxic insults in the brain, is activated by EV71 infection of neuronal cells. EV71-induced neuronal apoptosis could be effectively repressed by blocking either Cdk5 kinase activity or its protein expression. Moreover, EV71-induced Cdk5 activation was modulated by c-Abl. The suppression of c-Abl kinase activity by STI571 notably repressed both the Cdk5 activation and neuronal apoptosis in cells infected with EV71. Although EV71 also induces apoptosis in non-neuronal cells, it did not affect Abl and Cdk5 activities in several non-neuronal cell lines. Intriguingly, coxsackievirus A16 (CA16), a genetically closely related serotype to EV71 that usually does not induce severe neurological disorders, could only weakly stimulate Abl, but not Cdk5 kinase activity. Taken together, our data suggest a serotype- and cell type-specific mechanism, by which EV71 induces Abl kinase activity, which in turn triggers Cdk5-signalling for neuronal apoptosis.

Epidemiologic and virologic investigation of hand, foot, and mouth disease, southern Vietnam, 2005

During 2005, 764 children were brought to a large children's hospital in Ho Chi Minh City, Vietnam, with a diagnosis of hand, foot, and mouth disease. All enrolled children had specimens (vesicle fluid, stool, throat swab) collected for enterovirus isolation by cell culture. An enterovirus was isolated from 411 (53.8%) of the specimens: 173 (42.1%) isolates were identified as human enterovirus 71 (HEV71) and 214 (52.1%) as coxsackievirus A16. Of the identified HEV71 infections, 51 (29.5%) were complicated by acute neurologic disease and 3 (1.7%) were fatal. HEV71 was isolated throughout the year, with a period of higher prevalence in October-November. Phylogenetic analysis of 23 HEV71 isolates showed that during the first half of 2005, viruses belonging to 3 subgenogroups, C1, C4, and a previously undescribed subgenogroup, C5, cocirculated in southern Vietnam. In the second half of the year, viruses belonging to subgenogroup C5 predominated during a period of higher HEV71 activity.

Outbreak of Neurologic Enterovirus Type 71 Disease: A Diagnostic Challenge

BACKGROUND

Similar to poliovirus, enterovirus type 71 (EV71) causes severe disease, including aseptic meningitis, encephalitis, acute flaccid paralysis, and acute cardiopulmonary dysfunction. Large epidemics of EV71 infection have been reported worldwide.

METHODS

After recognition of a cluster of cases of EV71 disease, we reviewed records of patients with EV71 disease who required hospitalization at The Children's Hospital in Denver, Colorado, from 2003 through 2005. The presence of enterovirus was detected by reverse-transcriptase polymerase chain reaction (PCR) and/or viral culture of specimens from multiple sources, and the virus was typed as EV71 using genetic sequencing.

RESULTS

Eight cases of EV71 disease were identified in both 2003 and 2005. Fifty-six percent of patients with EV71 disease were < or = 6 months of age (range, 4 weeks to 9 years). All 16 patients had EV71 central nervous system infection. Enterovirus PCR (EV-PCR) of cerebrospinal fluid specimens yielded positive results for only 5 (31.2%) of the 16 patients; all of these patients were < 4 months of age and had less severe disease. However, EV-PCR of upper respiratory tract specimens yielded positive results for 8 (100%) of 8 patients, and EV-PCR of lower gastrointestinal tract specimens yielded positive results for 7 (87.5%) of 8 patients.

CONCLUSIONS

An outbreak of neurologic EV71 disease occurred in Denver, Colorado, during 2003 and 2005. Likely, EV71 disease remains unrecognized in other parts of the United States, because EV-PCR of cerebrospinal fluid frequently yields negative results. EV-PCR of specimens from the respiratory and gastrointestinal tracts had higher diagnostic yields than did EV-PCR of cerebrospinal fluid. EV71 infection should be considered in young children presenting with aseptic meningitis, encephalitis, acute flaccid paralysis, or acute cardiopulmonary collapse. EV71 infection may be an underrecognized emerging disease in the United States.

Surgical Strategies for Brachial Plexus Polio-Like Paralysis

BACKGROUND

Brachial plexus polio-like paralysis is an acute flaccid paralysis of the upper limb following viral infection. Surgical approaches to the paralytic limb have not previously been discussed in the literature. This study is the first to describe the clinical course and propose a surgical strategy for disabilities related to poliomyelitis-like paralysis.

METHODS

Between 1982 and 2004, 17 patients (11 boys and six girls) presented with acute flaccid paralysis of the upper limb. Their clinical course was reviewed retrospectively. Average age at onset of disease was 2 years (range, 4 months to 13 years). All patients had disability in shoulder abduction and/or elbow flexion. Ten patients underwent reconstructive surgery.

RESULTS

Stage V shoulder abduction (>160 degrees) according to Gilbert's classification was regained in five patients who underwent nerve transfer within 1 year of paralysis. One patient treated by nerve transfer after 3 years of paralysis obtained only stage I abduction (<45 degrees). In two patients, multiple local muscle transfers were performed for the shoulder abduction disability, resulting in mild improvement from stage I to stage II abduction (<90 degrees). In four patients, functioning free muscle transplantation for elbow flexion was carried out, and all regained functional M4 muscle strength. Of seven patients in the nonsurgical group, two had complete spontaneous recovery within 1 year, but five had permanent residual limb paralysis at a mean follow-up of 10 years.

CONCLUSIONS

Surgical strategies, including nerve transfer for shoulder abduction deficit within 1 year after attack and functioning free muscle transplantation for the elbow flexion deficit in the late period, should be considered for this disease. Late reconstruction, either by nerve transfer or by using local multiple muscle transfer for shoulder abduction, is ineffective.

Epidemiologic features of hand-foot-mouth disease and herpangina caused by enterovirus 71 in Taiwan, 1998-2005

OBJECTIVE

In 1998, an epidemic of hand-foot-mouth disease/herpangina was caused by human enterovirus 71 infection in Taiwan. The underlying factors of widespread emergence of viral infection are unclear. The purpose of this study was to assess the epidemiology of hand-foot-mouth disease/herpangina in Taiwan between March 1998 and December 2005.

METHODS

We analyzed data reported to surveillance systems at the Taiwan Center for Disease Control. Viral isolation was performed by 11 reference virus laboratories at medical centers as well as the Taiwan Center for Disease Control.

RESULTS

During the 8-year study period, the reported incidence of mild cases of hand-foot-mouth disease/herpangina varied from 0.8 to 19.9 cases per sentinel physician per week, peaking in 1998. Seasonal variations in incidence were observed, with an incidence peak observed during the summer season. Annual incidence changed significantly from 1998 to 2005. Both age-specific incidence and fatality of severe hand-foot-mouth disease/herpangina decreased as age increased. Most (93%) cases occurred in children who were aged 4 years and younger. Inpatients had a higher rate of enterovirus 71 infection than outpatients. Among severe cases, the majority (80%) had pulmonary edema/hemorrhage and encephalitis.

CONCLUSIONS

Hand-foot-mouth disease/herpangina is a common disease in Taiwan. Enterovirus 71 infection has emerged as an important public problem causing serious clinical illness and, potentially, death in young children. Vaccine development is recommended for prevention of enterovirus 71 infection in the future.

Enterovirus 71 meningoencephalitis during chemotherapy in a child with metastatic osteosarcoma

Enterovirus meningoencephalitis is rare but can be severe. Very few cases of these infections have been reported in pediatric oncology. We report the case of a 10-year-old boy with tibial osteosarcoma and lung metastases who developed enterovirus 71 meningoencephalitis during aplasia. Clinical features comprised fever, hypotension, vesicular rash, generalized seizures, and altered consciousness. Diagnosis was confirmed by polymerase chain reaction on samples of cerebrospinal fluid and skin vesicles. The patient received treatment with intravenous immunoglobulins with an excellent outcome with no cutaneous or neurologic sequelae. Immunoglobulin therapy could be considered in cases of invasive enteroviral infection with such severity in pediatric oncology.

Restoration of shoulder function and elbow flexion by nerve transfer for poliomyelitis-like paralysis caused by enterovirus 71 infection

We report the case of an eight-month-old girl who presented with a poliomyelitis-like paralysis in her left upper limb caused by enterovirus 71 infection. She recovered useful function after nerve transfers performed six months after the onset of paralysis. Early neurotisation can be used successfully in the treatment of poliomyelitis-like paralysis in children.

Diagnostic approaches for patients with suspected encephalitis

Encephalitis represents a diagnostic challenge, with an infectious etiology identified in only 40% to 70% of cases. More than 100 agents have been either definitively or anecdotally associated with encephalitis. Important considerations for diagnosis include selection of the appropriate clinical specimen (serum vs cerebrospinal fluid), determining the most sensitive diagnostic assay (serology vs polymerase chain reaction), and assessing causality when an organism is identified outside of the central nervous system (eg, a positive nasal swab for influenza). This review aims to provide an evidence-based, clinically relevant approach to the diagnostic evaluation of patients presenting with encephalitis, focusing on the most common or important causes in the immunocompetent host. Diagnostic issues associated with encephalitis due to herpes-group viruses, arboviruses (including West Nile virus), rickettsiae, bartonella, enteroviruses, and rabies are discussed in-depth. Diagnostic testing should be individualized based on clinical presentation and epidemiology.

An attenuated strain of enterovirus 71 belonging to genotype a showed a broad spectrum of antigenicity with attenuated neurovirulence in cynomolgus monkeys

Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and is also sometimes associated with serious neurological disorders. In this study, we characterized the antigenicity and tissue specificity of an attenuated strain of EV71 [EV71(S1-3')], which belongs to genotype A, in a monkey infection model. Three cynomolgus monkeys were inoculated with EV71(S1-3'), followed by lethal challenge with the parental virulent strain EV71(BrCr-TR) via an intravenous route on day 45 postinoculation of EV71(S1-3'). Monkeys inoculated with EV71(S1-3') showed a mild neurological symptom (tremor) but survived lethal challenge by virulent EV71(BrCr-TR) without exacerbation of the symptom. The immunized monkey sera showed a broad spectrum of neutralizing activity against different genotypes of EV71, including genotypes A, B1, B4, C2, and C4. For the strains examined, the sera showed the highest neutralization activity against the homotype (genotype A) and the lowest neutralization activity against genotype C2. The order of decreasing neutralization activity of sera was as follows: A > B1 > C4 > B4 > C2. To examine the tissue specificity of EV71(S1-3'), two monkeys were intravenously inoculated with EV71(S1-3'), followed by examination of virus distribution in the central nervous system (CNS) and extraneural tissues. In the CNS, EV71(S1-3') was isolated only from the spinal cord. These results indicate that EV71(S1-3') acts as an effective antigen, although this attenuated strain was still neurotropic when inoculated via the intravenous route.

Cerebrospinal fluid cytokines in enterovirus 71 brain stem encephalitis and echovirus meningitis infections of varying severity

Taiwan has experienced several outbreaks of enterovirus 71 (EV71) infections since 1998. This study examined the quantitative relationship between specific cytokines in the cerebrospinal fluid (CSF) and the severity of EV71 brain stem encephalitis (BE), and investigated whether the CSF cytokine response differed from that to uncomplicated echovirus meningitis (EM). The study included 57 children with EV71 BE, of whom 24 had isolated BE, 24 had autonomic nervous system (ANS) dysregulation, and nine had pulmonary oedema (PE), and 15 children with EM. All were confirmed by virus culture. Mean CSF glucose, total protein and lactate levels were increased significantly in association with the severity of EV71 BE. The mean CSF concentration of interleukin (IL)-1beta in children with EV71 PE was significantly higher than in those with isolated BE. IL-6 and interferon (IFN)-gamma levels were significantly higher for EV71 PE and ANS dysregulation than for isolated BE. In contrast, EM was associated with high levels of IL-1beta and low levels of IFN-gamma. Cytokines in the central nervous system, as well as in blood, appear to be involved in the pathogenesis of EV71 BE.

Neurodevelopment and cognition in children after enterovirus 71 infection

BACKGROUND

Enterovirus 71 is a common cause of hand, foot, and mouth disease and encephalitis in Asia and elsewhere. The long-term neurologic and psychiatric effects of this viral infection on the central nervous system (CNS) are not well understood.

METHODS

We conducted long-term follow-up of 142 children after enterovirus 71 infection with CNS involvement - 61 who had aseptic meningitis, 53 who had severe CNS involvement, and 28 who had cardiopulmonary failure after CNS involvement. At a median follow-up of 2.9 years (range, 1.0 to 7.4) after infection, the children received physical and neurologic examinations. We administered the Denver Developmental Screening Test (DDST II) to children 6 years of age or younger and the Wechsler intelligence test to children 4 years of age or older.

RESULTS

Nine of the 16 patients with a poliomyelitis-like syndrome (56%) and 1 of the 5 patients with encephalomyelitis (20%) had sequelae involving limb weakness and atrophy. Eighteen of the 28 patients with cardiopulmonary failure after CNS involvement (64%) had limb weakness and atrophy, 17 (61%) required tube feeding, and 16 (57%) required ventilator support. Among patients who underwent DDST II assessment, delayed neurodevelopment was found in only 1 of 20 patients (5%) with severe CNS involvement and in 21 of 28 patients (75%) with cardiopulmonary failure (P<0.001 for the overall comparison). Children with cardiopulmonary failure after CNS involvement scored lower on intelligence tests than did children with CNS involvement alone (P=0.003).

CONCLUSIONS

Enterovirus 71 infection with CNS involvement and cardiopulmonary failure may be associated with neurologic sequelae, delayed neurodevelopment, and reduced cognitive functioning. Children with CNS involvement without cardiopulmonary failure did well on neurodevelopment tests. (ClinicalTrials.gov number, NCT00172393 [ClinicalTrials.gov].).

The correlation between neurological evaluations and neurological outcome in acute encephalitis: a hospital-based study

Acute encephalitis is a common CNS infectious disease in children. However, there are limited studies concerning about the correlation between the clinical evaluations and neurological outcome. To investigate the value of neurological evaluations, and the correlation between these evaluations and neurological outcomes of acute encephalitis, in the present study we retrospectively evaluated the neurological outcome of 0- to 16-year-old children with encephalitis or meningoencephalitis between 1999 and 2000. Of 101 children enrolled, 4 died and 25 had other neurological sequelae, including epilepsy, headache, developmental delay, and emotional or behavioral changes during the 5 years of follow-up. The causative organisms in patients with neurological sequelae were herpes virus (HSV) 2/2 (100%), influenza 2/3 (67%), mycoplasma 5/12 (42%), and enterovirus 71 2/7 (29%). The important predictors for adverse outcomes were focal neurological signs, multiple seizures or status epilepticus on admission, leukopenia, focal slow waves or continuous generalized delta waves in electroencephalography (EEG), and focal cortical parenchymal hyperintensity in the magnetic resonance imaging (MRI) (p<0.05). Patients with initial presentations of focal neurological signs, papilledema, myoclonic jerks, and status epilepticus tended to have higher incidence of abnormal findings in brain MRI, although not achieving statistic significances. In addition, children with focal spikes or continuous generalized delta waves in EEG also had higher incidence of MRI abnormalities. We conclude that brain MRI studies may be indicated in patients with focal neurological signs, intractable seizure, and focal spikes, focal delta waves, or continuous generalized delta waves in EEG. For those with MRI examinations, focal cortical hyperintensity suggests poorer neurological outcomes.

Differences in replication capacity between enterovirus 71 isolates obtained from patients with encephalitis and those obtained from patients with herpangina in Taiwan

The cellular-tropism and biological characteristics of enterovirus 71 (EV71) isolates in Taiwan (TW) were studied. Growth curve experiments were conducted using cell lines that were possibly exhibited pathogenesis, and RT-PCR and sequencing tests were undertaken to amplify the 5' non-coding region (5'-NCR). The encephalitis isolate EV71 TW98NTU2078 was PBMC-tropic, temperature-resistant (Tr) at 40 degrees C, and easier to replicate in HTB-14 (astrocytoma) than the herpangina isolate EV71 TW98NTU1186 (The viral yields were 100-fold higher than those of the herpangina isolate EV71 TW98NTU1186 at 96 hr post infection.). The herpangina isolate EV71 TW98NTU1186 was non-PBMC-tropic, and temperature-sensitive (Ts) at 40 degrees C. The replication of EV71 TW98NTU1186 in HTB-14 was lower. No EV71 isolate infected HTB-37 (human colon adenocarcinoma cells). The encephalitis EV71 isolate exhibited better replication and transmission in PBMCs and astrocytes than did the EV71 isolate without CNS involvement.

New enteroviruses, EV-93 and EV-94, associated with acute flaccid paralysis in the Democratic Republic of the Congo

Surveillance of acute flaccid paralysis often identifies enteroviruses not typeable by virus neutralization in cell culture. During 2000 and 2001, 186 isolates from 138 children with acute flaccid paralysis in the Democratic Republic of the Congo were sent for typing to the National Reference Centre for Enteroviruses in Lyon, France. The 5' UTR of the viral genome could be amplified by PCR for 158 isolates from 114 patients. Isolates from 89 patients were neutralizable, and contained non-polio enterovirus types. Seventeen children were infected with more than one entero- or adenovirus; another three were co-infected with both these viruses. Serological typing failed with 19 isolates from 13 (9%) patients. The VP1 region of these strains could be amplified by PCR and sequenced, which revealed that five children were infected with CV-A17, EV-70, EV-76, EV-77, or CV-A13. Two patients were doubly infected, one with CV-A24 and E-9, and another with E-27 and EV-81. Isolates from six children contained strains with divergent VP1 region. The amino acid sequences of these complete VP1 regions diverged >or=28% from published types indicating that they represented two new enterovirus types, tentatively designated EV-93 belonging to HEV-B and EV-94 within HEV-D. The latter enterovirus has in parallel been isolated from sewage in Egypt. In conclusion, there was a high frequency of "untypable" enterovirus isolates from cases with acute flaccid paralysis in the Democratic Republic of the Congo. Six of these were shown to represent two enteroviruses not previously described.

Long-term cognitive and motor deficits after enterovirus 71 brainstem encephalitis in children

OBJECTIVES

Several large outbreaks of enterovirus 71 infections have occurred in Taiwan during the past decade. Brainstem encephalitis was the most common neurologic complication. This study was designed to determine the long-term cognitive and motor outcomes of children with enterovirus 71 brainstem encephalitis.

METHODS

We conducted a prospective follow-up study of children who met the case definition for enterovirus 71 brainstem encephalitis. Subjects were stratified into isolated brainstem encephalitis (stage II), autonomic nervous system dysregulation (stage IIIa), and pulmonary edema (stage IIIb). The subjects and their parents or guardians were interviewed using structured questionnaires and received comprehensive cognitive and neurologic examinations. Motor coordination, visual-motor skill, and intellectual ability were evaluated.

RESULTS

Follow-up studies were conducted in 63 previously healthy children with enterovirus 71 brainstem encephalitis (49 stage II, 7 stage IIIa, and 7 stage IIIb). The mean time to follow-up was 2.8 +/- 1.0 years (range: 1.4-4.9 years). Boys outnumbered girls by 3 to 2. The mean age at diagnosis was 2.4 +/- 1.4 years (range: 0.3-7.1 years). The most common abnormal neurologic findings on admission were altered consciousness (47.6%), followed by abnormal activities of daily living (52.4%), cerebellar dysfunction (17.5%), and cranial nerve palsy (15.9%). At follow-up, 51 of 63 children had no detectable deficits. Among the remaining 12 children, 3 died during the follow-up. The remaining 9 children (14.3%) had residual deficits. Two of these with stage IIIb disease continued to have severe motor and respiratory failure.

CONCLUSIONS

Residual defects were still present in a significant proportion of children with enterovirus 71 brainstem encephalitis at >2 years after their hospitalization. Children with stage II disease were most likely to have residual cerebellar defects. Those with stage IIIb disease continued to have severe respiratory and motor impairment. Long-term follow-up of this cohort is needed to determine the ultimate prognosis.

Heart rate variability monitoring in the detection of central nervous system complications in children with enterovirus infection

PURPOSE

Previous studies suggest the possibility of autonomic dysfunction in patients with complicated hand, foot, and mouth disease (HFMD) and herpangina. Heart rate variability (HRV), an index for autonomic nervous system, may be useful to detect disease progression.

MATERIALS AND METHODS

From 2001 to 2002, 66 patients (1-9 years old) were enrolled prospectively in either a control (20 patients) or disease (46 patients with HFMD or herpangina) group. The disease group was subdivided into stage I (fever only), stage II (with complications of encephalomyelitis), and stage III (with complications of encephalomyelitis as well as tachycardia, hyperglycemia, tachypnea, and hypertension or hypotension) groups. Data from electrocardiograms were transformed for HRV.

RESULTS

The HRV parameters generally decreased and the low frequency (LF)/high frequency ratio (HF) increased in the disease groups. Patients in disease group stage II had significantly lower parameters of HRV (triangular index, total power, LF power, and HF power) and higher LF/HF ratio than those in disease group stage I. With this trend, patients with stage III disease had extremely low HRV parameters. The inferred criteria of HRV (standard deviation of normal-to-normal interval <17 milliseconds and HF power <24 milliseconds(2)) to define stage III patients (sensitivity, 100%; specificity, 71.4%) were also useful to predict disease progression.

CONCLUSIONS

The HRV markedly decreased, most likely because of autonomic dysfunction, in patients with HFMD and herpangina when complicated with central nervous system involvement and cardiopulmonary failure and may be useful parameters to monitor disease progression.

Modulation of cytokine production by intravenous immunoglobulin in patients with enterovirus 71-associated brainstem encephalitis

BACKGROUND

Several epidemics of enterovirus 71 (EV71) infections occurred in Taiwan since 1998.

OBJECTIVES

We performed the study to determine the changes in cytokine profiles associated with administration of intravenous immunoglobulin (IVIG) in patients with EV71-associated brainstem encephalitis complicated by autonomic nervous system (ANS) dysfunction and pulmonary edema.

STUDY DESIGN

Plasma cytokine concentrations (IL-1beta, IL-6, IL-8, IFN-gamma, TNF-alpha, IL-2, IL-4, IL-5, IL-10, and IL-13) were monitored on admission and within 12-24h after administration of IVIG in a cohort of children (n=22) with virologically confirmed EV71 infection, from March 2000 through April 2004.

RESULT

Plasma levels of IFN-gamma, IL-6, IL-8, IL-10, and IL-13 levels significantly decreased in patients with pulmonary edema after administration of IVIG, P<0.05. Plasma levels of IL-6 and IL-8 were significantly decreased in patients with ANS dysregulation after administration of IVIG, P<0.05. Administration of IVIG was not associated with significant changes in plasma concentration of IL-1beta, IL-2, IL-4, IL-5 IL-10, IL-13 and TNF-alpha in patients with ANS dysregulation.

CONCLUSIONS

These findings suggest that IVIG might be considered to have a therapeutic role in EV71-associated brainstem encephalitis. A clinical trial is needed to support this hypothesis.

Comparison of heart failure in children with enterovirus 71 rhombencephalitis and cats with norepinephrine cardiotoxicity

The mechanism of heart failure in patients with enterovirus 71 rhombencephalitis (brain stem encephalitis) remains unknown. Our previous reports hypothesized that a catecholamine storm induced by rhombencephalitis may account for the heart failure. The aim of this study was to develop a novel feline model of norepinephrine cardiotoxicity and compare the resulting heart failure to that in children with enterovirus 71 rhombencephalitis. Nine of 75 children (12%) with enterovirus 71 rhombencephalitis (5 boys and 4 girls; age, 4-28 months; median age, 16 months) were complicated with left ventricular hypokinesia (ejection fraction, 31 +/- 9%). Six cats (weight, 3.03 +/- 0.64 kg) were administered intravenous norepinephrine 30 microg/kg/min for 3 hours. Echocardiography assessed the left ventricular diameter and function before and after the administration of norepinephrine. Pathology studies included hematoxylin and eosin stain and in situ terminal deoxyribonucleotidyl transferase-mediated dUTP nick end-labeling assay. In the feline model, norepinephrine induced significant left ventricular dilatation (end diastolic diameter from 1.18 +/- 0.19 to 1.62 +/- 0.22 cm, p = 0.001; endsystolic diameter from 0.54 +/- 0.09 to 1.36 +/- 0.32 cm, p = < 0.001) and hypokinesia (ejection fraction from 87.5 +/- 4.1 to 35.2 +/- 16.3%, p = 0.001). Heart specimens from 4 patients and six cats showed similar pathology findings, including myocardial hemorrhage, cardiomyocyte apoptosis, and coagulative myocytolysis, which is characterized by sarcoplasmic coagulation, granulation, vacuolization, myofibrillar waving, and disruption. Both groups showed no significant inflammatory reaction. In conclusion, heart failure in patients with enterovirus 71 rhombencephalitis is similar to that in cats with norepinephrine cardiotoxicity. Norepinephrine cardiotoxicity may play a role in the pathogenesis of heart failure in enterovirus 71 rhombencephalitis.

Critical management in patients with severe enterovirus 71 infection

OBJECTIVE

The aim of this study was to analyze clinical details occurring in children with severe enterovirus 71 (EV71) infection and synthesize the critical care experience for patients with severe EV71 infection.

METHODS

A retrospective clinical, laboratory, and hemodynamic study was performed in a pediatric intensive care unit in a university hospital. From March 1998 to April 2000, seven consecutive pediatric patients with severe EV71 infection were retrospectively analyzed as the comparison group. From May 2000 to March 2003, eight consecutive patients with severe EV71 infection who had received the protocol therapy were enrolled as the study group. Detailed information about clinical treatment and pharmacological therapy was collected for comparison.

RESULTS

The clinical presentations and laboratory findings between the comparison and the study groups were not significantly different. The amount of intravenous fluid in the first 24 h was significantly higher in the comparison group (9.2+/-5.0 vs 4.9+/-1.3 mL/kg per h). More patients in the study group received low doses of dopamine infusion, patients in the comparison group received more epinephrine, and none of them received milrinone. The acute-stage and long-term survival rates were higher in the study group (100% vs 43%, 87% vs 29%).

CONCLUSION

Early cardiopulmonary support may prevent the vicious cycle of cardiopulmonary failure and improve the clinical outcome of severe EV71 infection. Milrinone may be the ideal inotropic agent for these patients. Echocardiography, a central line, and an arterial line could be an alternate method to replace direct intracardiac hemodynamic monitoring for guiding critical management.

Paediatric Investigators Collaborative Network on Infections in Canada (PICNIC) study of aseptic meningitis

Background

The seasonality, clinical and radiographic features and outcome of aseptic meningitis have been described for regional outbreaks but data from a wider geographic area is necessary to delineate the epidemiology of this condition.

Methods

A retrospective chart review was completed of children presenting with aseptic meningitis to eight Canadian pediatric hospitals over a two-year period.

Results

There were 233 cases of proven enteroviral (EV) meningitis, 495 cases of clinical aseptic meningitis and 74 cases of possible aseptic meningitis with most cases occurring July to October. Headache, vomiting, meningismus and photophobia were more common in children ≥ 5 years of age, while rash, diarrhea and cough were more common in children < 5 years of age. Pleocytosis was absent in 22.3% of children < 30 days of age with proven EV meningitis. Enterovirus was isolated in cerebrospinal fluid (CSF) from 154 of 389 patients (39.6%) who had viral culture performed, and a nucleic acid amplification test for enterovirus was positive in CSF from 81 of 149 patients (54.3%). Imaging of the head by computerized tomography or magnetic resonance imaging was completed in 96 cases (19.7%) and 24 had abnormal findings that were possibly related to meningitis while none had changes that were definitely related to meningitis. There was minimal morbidity and there were no deaths.

Conclusion

The clinical presentation of aseptic meningitis varies with the age of the child. Absence of CSF pleocytosis is common in infants < 30 days of age. Enterovirus is the predominant isolate, but no etiologic agent is identified in the majority of cases of aseptic meningitis in Canadian children.

Microchip, reverse transcription-polymerase chain reaction and culture methods to detect enterovirus infection in pediatric patients

BACKGROUND

Enterovirus infection usually presents with mild and self-limited illness in children. However, Enterovirus type 71 can be characterized by neurotropism and may cause severe illness or even sudden death. Early detection of the virus will allow a physician to provide intensive or aggressive intervention. The purpose of the present study was to compare sensitivity of two innovative laboratory methods, that is, the DR.EV microchip method (DR. Chip Biotechnology, Shin-Tsu, Taiwan) and the reverse transcription-polymerase chain reaction (RT-PCR) method following conventional virus culture in detecting enterovirus infection in pediatric patients with herpangina or hand-foot-mouth disease.

METHODS

A total of 87 children (age range: 1-8 years) were enrolled because of typical clinical findings of herpangina and hand-foot-mouth disease. Two hundred children selected after a careful clinical history review and physical examinations, were included as controls. All of these children had at least throat swab and rectal swab specimens taken and tested for evidence of enterovirus infection by microchip, RT-PCR and virus culture methods. In addition, 21 patients also had cerebrospinal fluid (CSF) specimens taken to test for possible central nervous system involvement.

RESULT

The test results obtained from the 200 healthy kindergarten children were all negative for enteroviral infection by these three methods. Among the 87 test patients, the positive rates for throat swab, rectal swab and CSF by DR.EV chip, RT-PCR and virus culture were 71%, 68%, and 45% (throat swab); 66%, 61%, and 33% (rectal swab); and 52%, 29%, and 5% (CSF), respectively. There was no significant difference in the positive rates between the DR.EV chip and the RT-PCR methods (P > 0.1) on all types of specimens. However, statistically significant differences in positive rates were noted between the DR.EV chip and the conventional virus culture methods on all types of specimens (P < 0.001). Sensitivity of the microchip, RT-PCR and virus culture methods, was 82%, 72%, and 53%, respectively.

CONCLUSION

The DR.EV chip method yielded a statistically higher positive rate and faster test results than the conventional viral culture method.

Clinical perspectives of emerging pathogens in bleeding disorders

As a result of immunological and nucleic-acid screening of plasma donations for transfusion-transmissible viruses, and the incorporation of viral reduction processes during plasma fractionation, coagulation-factor concentrates (CFC) are now judged safe in terms of many known infectious agents, including hepatitis B and C viruses, HIV, and human T-cell lymphotropic virus. However, emerging pathogens could pose future threats, particularly those with blood-borne stages that are resistant to viral-inactivation steps in the manufacturing process, such as non-lipid-coated viruses. As outlined in this Review, better understanding of infectious diseases allows challenges from newly described agents of potential concern in the future to be anticipated, but the processes of zoonotic transmission and genetic selection or modification ensure that plasma-derived products will continue to be subject to infectious concerns. Manufacturers of plasma-derived CFC have addressed the issue of emerging infectious agents by developing recombinant products that limit the need for human plasma during production. Such recombinant products have extended the safety profile of their predecessors by ensuring that all reagents used for cell culture, purification steps, and stabilisation and storage buffers are completely independent of human plasma.

Status of cellular rather than humoral immunity is correlated with clinical outcome of enterovirus 71

We valuated specific cellular and humoral immune response of cases of enterovirus 71 (EV71) infection and correlated immune response with clinical outcome. After obtaining informed consent, we enrolled 30 EV71 cases including 7 cases with brainstem encephalitis plus pulmonary edema, 12 cases of CNS (CNS) involvement and 11 uncomplicated cases. We measured antibodies specific to EV71, lymphocyte proliferation response and EV71-stimulated cellular response of Th1/Th2 cytokines and chemokines. The 7 EV71 cases involving brainstem encephalitis plus pulmonary edema had a significantly lower phytohemagglutinin stimulation index than other cases (p = 0.04). After EV71 stimulation of peripheral mononuclear cells, there was a significant increase in cellular Th1 cytokine (gamma-interferon) and proinflammatroy cytokines. However, cases with pulmonary edema had significantly lower cellular gamma-interferon (p = 0.04), lower cellular IL-1beta (p = 0.04), lower cellular IL-6 (p = 0.04), lower cellular tumor necrosis factor-alpha response (p = 0.04), and lower cellular macrophage inflammatory protein-1alpha (p = 0.04) response compared with other cases. Their titers of EV71 neutralizing antibodies demonstrated no difference among cases. These results suggest lower EV71-specific cellular response may be associated with immunopathogenesis of EV71-related pulmonary edema.

Experience and result of extracorporeal membrane oxygenation in treating fulminant myocarditis with shock: what mechanical support should be considered first?

BACKGROUND

Extracorporeal membrane oxygenation (ECMO), instead of ventricular assist device (VAD), could work as the first-line treatment of choice for fulminant myocarditis (FM) with profound shock if intraaortic balloon pumping was inadequate. We reviewed our experience in treating FM with ECMO and compared it with the literature that described the use of VAD.

METHODS

Fifteen consecutive patients (age 27.1 +/- 19.3 years) who had FM with profound shock were rescued with ECMO emergently. Hypotension, depressed left ventricular ejection fraction (19.1% +/- 6.1%), and oliguria occurred in all patients with high-dose catecholamine (inotropic equivalents: 69.0 +/- 37.7 microg/kg/min) and ventilator support. Before ECMO support, 6 patients received intraaortic balloon pumping support, 5 received external cardiac massage, 5 needed a temporary pacemaker, and 4 needed continuous hemofiltration. The pre-ECMO cardiac enzyme and liver enzyme levels were abnormally high.

RESULTS

Fourteen patients (93.3%) could be weaned off mechanical support. Three of 14 successfully weaned patients died later as a result of complications. Survival to discharge was 73.3%, and none of survivors needed heart transplantation. The ECMO duration was 137.7 +/- 74.5 hours. The ECMO-related neurological complication (6.7%) and the reexploration rate for hemostasis (8.9%) were lower than the myocarditis group supported by VAD from the literature review. The 11 survivors exhibited no cardiac dysfunction during the follow-up period.

CONCLUSIONS

Owning to advantages of fewer complications, easier application, and biventricular support, ECMO can be considered as the first-line treatment of mechanical support for FM with profound shock when intraaortic balloon pumping is inadequate or infeasible.

Type I interferons protect mice against enterovirus 71 infection

In this study, the contribution of type I interferons (IFNs) to protection against infection with enterovirus 71 (EV71) was investigated using a murine model where the virus was administrated to neonatal Institute of Cancer Research (ICR) mice by either the intraperitoneal (i.p.) or the oral route. In i.p. inoculated mice, post-infection treatment of dexamethasone (5 mg kg(-1) at 2 or 3 days after infection) exacerbated clinical symptoms and increased the tissue viral titre. In contrast, polyriboinosinic : polyribocytidylic acid [poly(I : C); 10 or 100 microg per mouse at 12 h before infection], a potent IFN inducer, improved the survival rate and decreased the tissue viral titres after EV71 challenge, which correlated with an increase in serum IFN-alpha concentration, the percentage of dendritic cells, their expression of major histocompatibility complex class II molecule and IFN-alpha in spleen. Treatment with a neutralizing antibody for type I IFNs (10(4) neutralizing units per mouse, 6 h before and 12 h after infection) resulted in frequent deaths and higher tissue viral load in infected mice compared with control mice. In contrast, an early administration of recombinant mouse IFN-alphaA (10(4) U per mouse for 3 days starting at 0, 1 or 3 days after infection) protected the mice against EV71 infection. In vitro analysis of virus-induced death in three human cell lines showed that human type I IFNs exerted a direct protective effect on EV71. It was concluded that type I IFNs play an important role in controlling EV71 infection and replication.

Serial Electrodiagnostic Studies in West Nile Virus–Associated Acute Flaccid Paralysis

A man in his 70s presented for acute rehabilitation with severe acute flaccid asymmetric weakness in both lower limbs. Cerebrospinal fluid and serum immunoglobulin M titers were positive for West Nile virus. Electrodiagnostic studies demonstrated severe diffuse motor axonopathy consistent with an anterior myelitis. Electrodiagnostic and clinical improvements were monitored. Electrodiagnostic testing at 6 and 18 mos demonstrated continuing reinnervation; nascent voluntary motor unit action potentials were first noted proximally and, at 18 mos, distally in the left lower limb, including muscles in which motor unit potentials were not initially noted. Corresponding clinical improvements, though slow, were demonstrated even at 1(1/2) yrs after onset. Thus, motoric changes after West Nile virus-associated anterior myelitis need to be monitored over a prolonged time period to allow accurate assessment of prognosis for recovery in rehabilitation programs.

Enteroviruses as agents of emerging infectious diseases

Although the enteroviruses as a group are ubiquitous and not normally considered as "emerging pathogens," the many different serotypes circulate at different frequencies in any given year and the prevalence of a given serotype may fluctuate wildly from year to year. As a result, several enterovirus serotypes have been associated with the emergence of specific diseases (for example, pandemic acute hemorrhagic conjunctivitis) and specific serotypes have emerged to cause outbreaks of major public health concern. Enterovirus 71 is a recognized cause of epidemic severe central nervous system disease in Southeast Asia. Acute hemorrhagic conjunctivitis was a newly described disease in the 1970s associated with emergence of enterovirus 70 and coxsackievirus A24 variant. In addition, the impending eradication of poliovirus and some of the challenges currently faced by the eradication program present the possibility that poliomyelitis could emerge in the posteradication era. These links between enterovirus infections and emerging diseases are reviewed.

Diverse apoptotic pathways in enterovirus 71-infected cells

Mechanisms related to the neuropathogenesis of enterovirus 71 infection remain unclear. This investigation conducts a comprehensive study of the apoptotic pathways in neural and non-neural cells following enterovirus 71 infection. Infections with enterovirus 71 not only induce classical cytopathic effects in SF268 (human glioblastoma), SK-N-MC (human neuroblastoma), RD, and Vero cells, but also induce classic signs of apoptosis in all cells, including DNA fragmentation and phosphatidylserine translocation. Apoptosis has also been caused by the efflux of cytochrome c from mitochondria, and subsequently by cleavage of caspase 9 in all cells. Activation of caspase 8 followed by cleavage of the proapoptotic protein Bid only occurs in non-neural cells. Results of this study demonstrate that a mitochondrial pathway of apoptosis mediated by activation and cleavage of caspase 9 is a main pathway in enterovirus 71-induced apoptosis, especially for enterovirus 71-infected neural cells.

[Neuromeningeal enterovirus infections in Tunisia: epidemiology, clinical presentation, and outcome of 26 pediatric cases]

Non-polio enteroviruses are the most common identified cause of viral neuromeningeal infections following the introduction of the mumps and polio vaccines.

OBJECTIVE

The aim of this study was to describe the epidemiology, clinical presentation, and the outcome of enteroviral infections of the CNS.

METHOD AND PATIENTS

We performed a prospective study on 41 children admitted for viral neuromeningeal infections in the pediatric department of Monastir between December 2001 and November 2002. Enteroviruses were detected from cerebrospinal fluid by RT-PCR.

RESULTS

This study showed that enteroviruses were responsible for 63.4% of the infections. The mean age of patients was 6.1 years. Aseptic meningitis was diagnosed in 14 cases and encephalitis in 10. The most frequent symptom was fever (61.5%), followed by seizures (42.3%), and confusion (23%). On follow-up, all patients with meningitis had recovered without sequels. Neurological complications in patients with encephalitis were epilepsy (3 cases), cerebral palsy (2 cases), and mental retardation (1 case).

CONCLUSION

This study confirmed that enteroviruses were the most common cause of viral infections of the CNS. Common use of RT-PCR can have a significant impact on the outcome of patients with enterovirus infections.

Viral diseases of the central nervous system

Viral diseases of the central nervous system encompass a wide range of different processes, mainly inflammation affecting the brain (encephalitis), the meninges (meningitis), or a combined meningoencephalitis. The spinal cord can be affected as well (myelitis). Another group of viral-related disorders, sometimes without a clear pathophysiological mechanism disclosed, include post-viral illnesses. All of these groups of diseases are discussed in this article, with an emphasis on their imaging presentation, using magnetic resonance imaging.