The 1998 enterovirus 71 outbreak in Taiwan: pathogenesis and management

EV71 induces COX-2 expression via c-Src/PDGFR/PI3K/Akt/p42/p44 MAPK/AP-1 and NF-kappaB in rat brain astrocytes

Enterovirus 71 (EV71) induces the expression of cyclooxgenase (COX)-2 served as a major neurotoxic factor in CNS injury. However, the mechanisms underlying EV71-initiated intracellular signaling pathways leading to COX-2 expression remain unknown. Therefore, we investigated the mechanisms underlying EV71-induced COX-2 expression and prostaglandin E(2) (PGE(2)) production in rat brain astrocytes (RBA)-1, determined by Western blotting, RT-PCR, and promoter assay. Here, we reported that EV71-induced COX-2 expression and PGE(2) production were attenuated by pretreatment with the inhibitors of c-Src (PP1), PDGFR (AG1296), PI3K (Wortmannin), MEK1/2 (PD98059), NF-kappaB (helenalin), and AP-1 (Tanshinone) and transfection with shRNA or siRNA of c-Src, PDGFR, p85, c-Jun, c-Fos, ERK1, or ERK2. We further observed that EV71-induced activation of Akt and p42/p44 MAPK were mediated via c-Src and PDGFR. Pretreatment with PP1 attenuated EV71-stimulated phosphorylation of Src, PDGFR, Akt, and p42/p44 MAPK. Inhibition of PI3K by Wortmannin attenuated EV71-induced Akt and p42/p44 MAPK phosphorylation, but had no effect on PDGFR phosphorylation, suggesting that PDGFR is an upstream and p42/p44 MAPK is a downstream component of PI3K/Akt in these responses. EV71-stimulated NF-kappaB translocation from the cytoplasm to the nucleus, IkappaBalpha degradation and NF-kappaB promoter activity were attenuated by pretreatment with helenalin, but not AG1296, Wortmannin, and PD98059. EV71-induced c-Jun mRNA expression was attenuated by pretreatment with PD98059, AG1296, or Wortmannin. These results demonstrate that in RBA-1 cells, EV71-induced COX-2 expression associated with PGE(2) production is mediated through activation of c-Src/PDGFR/PI3K/Akt/p42/p44 MAPK to initiate the expression of AP-1.

A comparison of the biological characteristics of EV71 C4 subtypes from different epidemic strains

The comparative analysis of the biological characterization and the genetic background study of EV71 circulating strains is commonly recognized as basic work necessary for development of an effective EV71 vaccine. In this study, we sequenced five EV71 circulating strains, isolated from Fuyang, Hefei, Kunming and Shenzhen city of China and named them FY-23, FY-22, H44, K9 and S1 respectively. The sequence alignment demonstrated their genotypes be C4. The genetic distance of the VP1 gene from these isolates suggested that they were highly co-related with genetic identity similar to other previously reported EV71 strains in China. Additionally, these strains were identified to display some obvious proliferation dynamics and plaque morphology when propagated in Vero cells. However, a distinctive difference in pathogenic ability in neonatal mice was found. Some differences in cross neutralization test & immunogenic analysis were also found. All these results are related to the biological characterization of circulating EV71 strains in China and aid in the development of an EV71 vaccine in the future.

Circulating viruses associated with severe complicated enterovirus infection in Taiwan: a multi-year analysis

BACKGROUND

Few studies have investigated the viral isolation characteristics for severe complicated enterovirus infection (SCEI). This study evaluated the seasonality and contribution of circulated viruses to the chronologic trend and weekly reported SCEI epidemic.

METHODS

Enterovirus infection surveillance and virology laboratory data in 2000 to 2008 obtained from the Centers for Disease Control in Taiwan were analyzed. We measured the monthly and weekly virology isolation rates by viral types. The virus-specific and the season-specific relative risks for SCEI and 95% confidence intervals (CI) associated with the isolated circulating viruses and weather status was evaluated.

RESULTS

Among 1539 virology confirmed SCEI cases, the mean annual incidence rates ranged from 0.72/100,000 to 32.5/100,000 in children aged 5 years and less; rates were higher in warm months with cases peaking in June (12.6%). The untypeable nonpolio enterovirus was the most frequently isolated type among the monitored specimens (6.07%), followed by coxsackievirus A (3.99%), EV71 (1.77%), coxsackievirus B (1.56%), and echovirus (1.23%). However, these SCEI cases had very strong associations with the isolation of EV71 and coxsackievirus A and B. The corresponding relative risks were 1.14 (95% CI, 1.11-1.17), 1.03 (95% CI, 1.01-1.04), and 1.09 (95% CI, 1.07-1.12), respectively, for 1% increase in weekly isolation rate.

CONCLUSIONS

Isolation rates for EV71 and coxsackieviruses A and B can predict the development of SCEI cases, particularly in warm months.

Development of enterovirus 71 vaccines

Enterovirus 71 (EV71) was first isolated in 1969 in California, USA. Several epidemic outbreaks with high mortality rates have occurred in European and Asian Countries (Bulgaria in 1975, Hungary in 1978, Malaysia in 1997, Taiwan in 1998 and China in 2008). EV71 CNS involvement may be associated with neurological sequelae, delayed neurodevelopment and reduced cognitive functioning. Since poliovirus was nearly eradicated by vaccination, EV71 is now considered as one of the top candidates for new vaccine development against human enteroviruses. Recently, several EV71 vaccine candidates, including live-attenuated virus, inactivated whole virus, recombinant viral protein, virus-like particle and DNA vaccines, have been evaluated in animals but no clinical trial has yet been conducted. Based on historical experiences with poliovirus vaccines and animal studies, the inactivated whole-virus vaccines are feasible and could be licensed readily, so these are targeted for preparing clinical trials in several organizations in Asia.

Extracorporeal life support for treatment of children with enterovirus 71 infection-related cardiopulmonary failure

PURPOSE

Enterovirus 71 (EV71) infection leading to cardiopulmonary failure (CPF) is rare, but usually fatal. In such cases, intensive cardiorespiratory support is essential for survival. In this study, we report our experience in the treatment of EV71-related CPF with extracorporeal life support (ECLS).

METHODS

This was a retrospective study of a total of 13 children, aged 16 +/- 10 months, with EV71-related hemodynamically unstable CPF, which was refractory to conventional treatments, who were rescued by transsternal ECLS from 2000 to 2008. The clinical manifestations and outcomes of the 13 children (present cohort) were compared with those of 10 children (past cohort) who had EV71-related CPF without ECLS between 1998 and 2000.

RESULTS

Among these 13 patients, 10 were successfully weaned off ECLS and survived. The myocardial recovery time was 71 +/- 28 (median, 69) h, and the ECLS duration was 93 +/- 33 (median, 93) h. Six surviving patients had a good neurological outcome at hospital discharge. All surviving patients had some neurological sequelae but showed improvement at follow-up, including dysphagia in nine, central hypoventilation in seven, limb weakness in six and seizure in three. The present cohort had better neurological outcomes (46 vs. 0%, P = 0.005) and a higher survival rate (77 vs. 30%, P = 0.024) than the past cohort, respectively.

CONCLUSIONS

Patients with EV71-related CPF supported by ECLS had a higher survival rate and fewer neurological sequelae than those who only received conventional treatments. ECLS is an effective alternative method for treatment of children with refractory EV71-related CPF.

Enterovirus 71: epidemiology, pathogenesis and management

Enterovirus 71 (EV71) has emerged as a major cause of neurological threat in the world following the eradication of poliovirus. Most EV71 infections commonly result in hand-foot-mouth disease or herpangina, and some cases are associated with brainstem encephalitis and acute flaccid paralysis. Mortality was high in EV71 brainstem encephalitis complicated with pulmonary edema, particularly in children below 5 years of age. Destruction of vasomotor in the brainstem by EV71 produces autonomic nervous system dysregulation prior to the pulmonary edema. The pulmonary edema is the result of increased pulmonary vascular permeability caused by the direct brainstem lesions and/or a systemic inflammatory response syndrome produced by the release of cytokines and chemokines. There is currently no specific antiviral agent to treat or vaccine to prevent EV71 diseases. Treating severe EV71 brainstem encephalitis patients with intravenous IgG and milrinone is associated with significantly decreased mortality by attenuated sympathetic activity and cytokine production.

Diseases caused by enterovirus 71 infection

The purpose of this review was to explore the epidemiology, pathogenesis, virology, and management of enterovirus 71 (EV71) infection. Published literature was surveyed by Medline using the keyword "EV71." The reported incidence of cases of hand-foot-mouth disease/herpangina varied from year to year; seasonal variations in incidence were observed, with a peak in incidence during the summer season. Most cases of hand-foot-mouth disease/herpangina hospitalized for complications occurred in children less than 5 years old. The brainstem was the most likely major target of EV71 infection. Different enteroviruses cocirculate in the community annually. The emergence of the EV71 epidemic in the Asia Pacific region has been associated with the circulation of 5 genetic lineages (genotypes B3, B4, C1, C2, C4) that appear to be undergoing rapid evolutionary changes. The relationship between the gene structure of the EV71 virus and the factors that ensure its survival, ease of transmission, and evasion of immunity is still unclear. EV71 central nervous system involvement causes serious clinical illness, death, and long-term neurologic and psychiatric disorders in young children. EV71 infection has emerged as an important public health problem. Vaccine development is recommended for the prevention of EV71 infection in the future.

Reemergence of enterovirus 71 in 2008 in taiwan: dynamics of genetic and antigenic evolution from 1998 to 2008

In recent years, enterovirus 71 (EV71) has been a cause of numerous outbreaks of hand-foot-and-mouth disease, with severe neurological complications in the Asia-Pacific region. The reemergence in Taiwan of EV71 genotype B5 in 2008 resulted in the largest outbreak of EV71 in Taiwan in the past 11 years. Phylogenetic analyses indicated that dominant genotype changes from B to C or C to B occurred at least three times between 1986 and 2008. Furthermore, antigenic cartography of EV71 by using neutralization tests revealed that the reemerging EV71 genotype B5 strains formed a separate cluster which was antigenically distinct from the B4 and C genotypes. Moreover, analyses of full-length genomic sequences of EV71 circulating in Taiwan during this period showed the occurrence of intra- and interserotypic recombination. Therefore, continuous surveillance of EV71 including the monitoring of genetic evolution and antigenic changes is recommended and may contribute to the development of a vaccine for EV71.

Antiviral effect of epigallocatechin gallate on enterovirus 71

Oxidative stress is known to be a determinant of a host's susceptibility to pathogens. Natural compounds with antioxidant activity may provide a preventive measure against infection. Tea polyphenols were evaluated for their ability to inhibit enterovirus 71 (EV71) replication in Vero cell culture. Among the polyphenolic compounds tested, epigallocatechin gallate (EGCG) and gallocatechin gallate (GCG) potently inhibited replication of EV71. EGCG and GCG reduced the titer of infectious progeny virus by 95%. Quantitative RT-PCR analysis also revealed that EGCG suppressed replication of genomic RNA. It was accompanied by an increased cytoprotective effect. EGCG and GCG caused 5-fold increase in the viability of EV71-infected cells. The viral inhibitory effect correlated well with the antioxidant capacity of polyphenol. Mechanistically, EV71 infection led to increased oxidative stress, as shown by increased dichlorofluorescein and MitoSOX Red fluorescence. Upon EGCG treatment, reactive oxygen species (ROS) generation was significantly reduced. Consistent with this, EV71 replication was enhanced in glucose-6-phosphate dehydrogenase deficient cells, and such enhancement was largely reversed by EGCG. These findings suggest that EGCG may suppress viral replication via modulation of cellular redox milieu.

Identification and validation of clinical predictors for the risk of neurological involvement in children with hand, foot, and mouth disease in Sarawak

Background

Human enterovirus 71 (HEV71) can cause Hand, foot, and mouth disease (HFMD) with neurological complications, which may rapidly progress to fulminant cardiorespiratory failure, and death. Early recognition of children at risk is the key to reduce acute mortality and morbidity.

Methods

We examined data collected through a prospective clinical study of HFMD conducted between 2000 and 2006 that included 3 distinct outbreaks of HEV71 to identify risk factors associated with neurological involvement in children with HFMD.

Results

Total duration of fever ≥ 3 days, peak temperature ≥ 38.5°C and history of lethargy were identified as independent risk factors for neurological involvement (evident by CSF pleocytosis) in the analysis of 725 children admitted during the first phase of the study. When they were validated in the second phase of the study, two or more (≥ 2) risk factors were present in 162 (65%) of 250 children with CSF pleocytosis compared with 56 (30%) of 186 children with no CSF pleocytosis (OR 4.27, 95% CI2.79–6.56, p < 0.0001). The usefulness of the three risk factors in identifying children with CSF pleocytosis on hospital admission during the second phase of the study was also tested. Peak temperature ≥ 38.5°C and history of lethargy had the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 28%(48/174), 89%(125/140), 76%(48/63) and 50%(125/251), respectively in predicting CSF pleocytosis in children that were seen within the first 2 days of febrile illness. For those presented on the 3^rd or later day of febrile illness, the sensitivity, specificity, PPV and NPV of ≥ 2 risk factors predictive of CSF pleocytosis were 75%(57/76), 59%(27/46), 75%(57/76) and 59%(27/46), respectively.

Conclusion

Three readily elicited clinical risk factors were identified to help detect children at risk of neurological involvement. These risk factors may serve as a guide to clinicians to decide the need for hospitalization and further investigation, including cerebrospinal fluid examination, and close monitoring for disease progression in children with HFMD.

Enterovirus-associated encephalitis in the California encephalitis project, 1998-2005

BACKGROUND

Encephalitis is a relatively rare presentation of enterovirus (EV) infections. Clinical and epidemiologic characteristics of EV encephalitis (EVE) have not been well characterized.

METHODS

Patients with encephalitis enrolled in the California Encephalitis Project from 1998 to 2005 were tested for a range of pathogens, including EV, using a standardized diagnostic algorithm. EVE was categorized as "confirmed" (EV detected in cerebrospinal fluid [CSF] or brain tissue) or "possible" (EV found in respiratory or fecal specimens or serum EV immunoglobulin [Ig] M detected). We compared clinical and epidemiologic characteristics of EVE with those of other infectious encephalitis cases.

RESULTS

EVE was diagnosed in 73 (4.6%) of 1571 patients (45 confirmed cases, 28 possible cases); 11.1% of cases had other infectious causes. Patients with confirmed EVE were younger, although 27% were adults, who presented with significantly less severe symptoms. Serotypes identified in EVE cases correlated with the predominant serotype for the given year reported to the National Enterovirus Surveillance System at the Centers for Disease Control and Prevention. Two of 4 fatal EVE cases were associated with EV71.

CONCLUSION

EVs are an important cause of encephalitis cases requiring hospitalization, in both children and adults. Our data suggest that EVE severity varies by serotype, confirm the importance of CSF/brain tissue polymerase chain reaction, and demonstrate that serum IgM findings are of little value in diagnosing EVE.

Simultaneous detection of human enterovirus 71 and coxsackievirus A16 in clinical specimens by multiplex real-time PCR with an internal amplification control

The recent and continuing HFMD outbreak caused by EV71 in several provinces of China since March 2008 has affected thousands of children and resulted in nearly 50 deaths. In this study, a sensitive and specific multiplex real-time RT-PCR assay has been developed for the rapid detection of EV71 and CV-A16. By using an internal amplification control, the real-time assay achieves detection of samples containing inhibitors and avoids false negatives. It should prove useful for clinical diagnosis of EV71 or CV-A16 infections.

Glucose-6-phosphate dehydrogenase deficiency enhances enterovirus 71 infection

Variations in the cellular microenvironment affect the host's susceptibility to pathogens. Using glucose-6-phosphate dehydrogenase (G6PD)-deficient fibroblasts as a model, this study demonstrated that the cellular redox status affects infectivity as well as the outcome of enterovirus 71 (EV71) infection. Compared with their normal counterparts, G6PD-deficient cells supported EV71 replication more efficiently and showed greater cytopathic effect and loss of viability. Mechanistically, viral infection led to increased oxidative stress, as indicated by increased dichlorofluorescein fluorescence and a diminished ratio of glutathione (GSH) to its disulfide form (GSSG), with the effect being greater in G6PD-deficient cells. Exogenous expression of active G6PD in the deficient cells, which increased the intracellular GSH : GSSG ratio, suppressed the generation of viral progeny. Consistent with this, treatment with N-acetylcysteine offered resistance to EV71 propagation and a cytoprotective effect on the infected cells. These findings support the notion that G6PD status, and thus redox balance, is an important determinant of enteroviral 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.

Attention-deficit/hyperactivity-related symptoms among children with enterovirus 71 infection of the central nervous system

BACKGROUND

No study has investigated the association between enterovirus 71 central nervous system infection and symptoms related to attention-deficit/hyperactivity disorder. In this study we evaluated attention-deficit/hyperactivity disorder-related symptoms and internalizing problems as long-term sequelae resulting from enterovirus 71 central nervous system infection in children.

METHODS

We enrolled 86 children 4 to 16 years old with virus-culture-confirmed enterovirus 71 infection and central nervous system involvement diagnosed 3 to 7 years before the study and 172 control subjects, matched for age, gender, and parents' education levels. Their mothers and teachers were asked to report on possible attention-deficit/hyperactivity disorder-related symptoms, and their mothers were asked to report on possible internalizing problems. All of the children previously infected with enterovirus 71 received intelligence tests.

RESULTS

Forty-two (49%) of the children previously infected with enterovirus 71 had had viral meningitis; 35 (41%) had severe central nervous system involvement, such as encephalitis, poliomyelitis-like syndrome, or encephalomyelitis; and 9 (10%) had cardiopulmonary failure and central nervous system involvement. The children previously infected with enterovirus 71 had higher scores than matched control subjects on teacher- and mother-rated scales of inattention, hyperactivity-impulsivity, oppositional symptoms, and attention-deficit/hyperactivity disorder index. The rate of elevated attention-deficit/hyperactivity disorder-related symptoms among children with enterovirus 71 central nervous system infection was 20%, whereas that rate among matched control subjects was only 3%. They also had more internalizing problems. Their verbal and performance IQs, as well as verbal comprehension indices, were significantly inversely correlated with symptoms of inattention, hyperactivity-impulsivity, and attention-deficit/hyperactivity disorder index scores.

CONCLUSIONS

Enterovirus 71 central nervous system infection may affect long-term regulation of attention and emotion and cause hyperactivity-impulsivity in children.

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.

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.

Establishing a nationwide emergency department-based syndromic surveillance system for better public health responses in Taiwan

Background

With international concern over emerging infectious diseases (EID) and bioterrorist attacks, public health is being required to have early outbreak detection systems. A disease surveillance team was organized to establish a hospital emergency department-based syndromic surveillance system (ED-SSS) capable of automatically transmitting patient data electronically from the hospitals responsible for emergency care throughout the country to the Centers for Disease Control in Taiwan (Taiwan-CDC) starting March, 2004. This report describes the challenges and steps involved in developing ED-SSS and the timely information it provides to improve in public health decision-making.

Methods

Between June 2003 and March 2004, after comparing various surveillance systems used around the world and consulting with ED physicians, pediatricians and internal medicine physicians involved in infectious disease control, the Syndromic Surveillance Research Team in Taiwan worked with the Real-time Outbreak and Disease Surveillance (RODS) Laboratory at the University of Pittsburgh to create Taiwan's ED-SSS. The system was evaluated by analyzing daily electronic ED data received in real-time from the 189 hospitals participating in this system between April 1, 2004 and March 31, 2005.

Results

Taiwan's ED-SSS identified winter and summer spikes in two syndrome groups: influenza-like illnesses and respiratory syndrome illnesses, while total numbers of ED visits were significantly higher on weekends, national holidays and the days of Chinese lunar new year than weekdays (p < 0.001). It also identified increases in the upper, lower, and total gastrointestinal (GI) syndrome groups starting in November 2004 and two clear spikes in enterovirus-like infections coinciding with the two school semesters. Using ED-SSS for surveillance of influenza-like illnesses and enteroviruses-related infections has improved Taiwan's pandemic flu preparedness and disease control capabilities.

Conclusion

Taiwan's ED-SSS represents the first nationwide real-time syndromic surveillance system ever established in Asia. The experiences reported herein can encourage other countries to develop their own surveillance systems. The system can be adapted to other cultural and language environments for better global surveillance of infectious diseases and international collaboration.

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.

EV71 induces VCAM-1 expression via PDGF receptor, PI3-K/Akt, p38 MAPK, JNK and NF-κB in vascular smooth muscle cells

Enterovirus 71 (EV71) is a widespread virus that causes severe and fatal diseases in patients, including circulation failure. The mechanisms underlying EV71-initiated intracellular signaling pathways to influence host cell functions remain unknown. In this study, we identified a requirement for PDGFR, PI3-K/Akt, p38 MAPK, JNK, and NF-kappaB in the regulation of VCAM-1 expression by rat vascular smooth muscle cells (VSMCs) in response to viral infection. EV71 induced VCAM-1 expression in a time- and viral concentration-dependent manner. Infection of VSMCs with EV71 stimulated VCAM-1 expression and phosphorylation of PDGFR, Akt, and p38 MAPK which were attenuated by AG1296, wortmannin, and SB202190, respectively. The phosphorylation of JNK stimulated by EV71 was not detected under present conditions. In contrast, JNK inhibitor SP600125 inhibited EV71-induced VCAM-1 expression. Furthermore, VCAM-1 expression induced by EV71 was significantly attenuated by a selective NF-kappaB inhibitor (helenalin). Consistently, EV71-stimulated translocation of NF-kappaB into the nucleus and degradation of IkappaB-alpha as well as VCAM-1 mRNA expression was blocked by helenalin, AG1296, SB202190, SP600125, wortmannin, and LY294002. Moreover, the involvement of p38 MAPK, PI3-K/Akt, and NF-kappaB in EV71-induced VCAM-1 expression was reveled by that transfection with dominant negative plasmids of p38 MAPK, p85, Akt, NIK, IKK-alpha, and IKK-beta attenuated these responses. These findings suggest that in VSMCs, EV71-induced VCAM-1 expression was mediated through activation of PDGFR, PI3-K/Akt, p38 MAPK, JNK, and NF-kappaB pathways.

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.

Retrograde axonal transport: a major transmission route of enterovirus 71 in mice

Inoculation of enterovirus 71 (EV71) by the oral (p.o.), intramuscular (i.m.), or intracranial route resulted in brain infection, flaccid paralysis, pulmonary dysfunction, and death of 7-day-old mice. The lag time of disease progression indicated that neuroinvasion from the inoculation sites was a prerequisite for the development of the clinical signs. Although EV71 p.o. inoculation led to a persistent viremia and a transient increase in blood-brain barrier permeability at the early stage of the infection, only low levels of virus, which led to neither severe infection nor clinical illness, could be detected in the brain, suggesting that hematogenous transport might not represent a major transmission route. In the spinal cord, following both p.o. and hind limb i.m. inoculation, the virus first appeared and increased rapidly in the lower segments, especially at the anterior horn areas, and then spread to the upper segments and brain in the presence of viremia. A reverse pattern, with the virus being first detected in the upper segment, was observed when the virus was i.m. inoculated in the forelimb. Colchicine, a fast axonal transport inhibitor, but not sciatic nerve transection reduced EV71 neuroinvasion in a dose-dependent manner, indicating a neuronal transmission of the virus.

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].).

Human Enterovirus 71 Disease in Sarawak, Malaysia: A Prospective Clinical, Virological, and Molecular Epidemiological Study

BACKGROUND

Human enterovirus (HEV)-71 causes large outbreaks of hand-foot-and-mouth disease with central nervous system (CNS) complications, but the role of HEV-71 genogroups or dual infection with other viruses in causing severe disease is unclear.

METHODS

We prospectively studied children with suspected HEV-71 (i.e., hand-foot-and-mouth disease, CNS disease, or both) over 3.5 years, using detailed virological investigation and genogroup analysis of all isolates.

RESULTS

Seven hundred seventy-three children were recruited, 277 of whom were infected with HEV-71, including 28 who were coinfected with other viruses. Risk factors for CNS disease in HEV-71 included young age, fever, vomiting, mouth ulcers, breathlessness, cold limbs, and poor urine output. Genogroup analysis for the HEV-71-infected patients revealed that 168 were infected with genogroup B4, 68 with C1, and 41 with a newly emerged genogroup, B5. Children with HEV-71 genogroup B4 were less likely to have CNS complications than those with other genogroups (26 [15%] of 168 vs. 30 [28%] of 109; odds ratio [OR], 0.48; 95% confidence interval [CI], 0.26-0.91; P=.0223) and less likely to be part of a family cluster (12 [7%] of 168 vs. 29 [27%] of 109; OR, 0.21; 95% CI, 0.10-0.46; P<.0001); children with HEV-71 genogroup B5 were more likely to be part of a family cluster (OR, 6.26; 95% CI, 2.77-14.18; P<.0001). Children with HEV-71 and coinfected with another enterovirus or adenovirus were no more likely to have CNS disease.

CONCLUSIONS

Genogroups of HEV-71 may differ with regard to the risk of causing CNS disease and the association with family clusters. Dual infections are common, and all possible causes should be excluded before accepting that the first virus identified is the causal agent.

Combining multiplex reverse transcription-PCR and a diagnostic microarray to detect and differentiate enterovirus 71 and coxsackievirus A16

Cluster A enteroviruses, including enterovirus 71 (EV71) and coxsackievirus A16 (CA16), are known to cause hand-foot-and-mouth disease (HFMD). Despite the close genetic relationship between these two viruses, EV71 is generally known to be a more perpetuating pathogen involved in severe clinical manifestations and deaths. While the serotyping of enteroviruses is mostly done by conventional immunological methods, many clinical isolates remain unclassifiable due to the limited number of antibodies against enterovirus surface proteins. Array-based assays are able to detect several serotypes with high accuracy. We combined an enterovirus microarray with multiplex reverse transcription-PCR to try to develop a method of sensitively and accurately detecting and differentiating EV71 and CA16. In an effort to design serotype-specific probes for detection of the virus, we first did an elaborate bioinformatic analysis of the sequence database derived from different enterovirus serotypes. We then constructed a microarray using 60-mer degenerate oligonucleotide probes covalently bound to array slides. Using this enterovirus microarray to study 144 clinical specimens from patients infected with HFMD or suspected to have HFMD, we found that it had a diagnostic accuracy of 92.0% for EV71 and 95.8% for CA16. Diagnostic accuracy for other enteroviruses (non-EV71 or -CA16) was 92.0%. All specimens were analyzed in parallel by real-time PCR and subsequently confirmed by neutralization tests. This highly sensitive array-based assay may become a useful alternative in clinical diagnostics of EV71 and CA16.

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.

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.

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.

Therapeutic efficacy of milrinone in the management of enterovirus 71-induced pulmonary edema

Hand, foot, and mouth disease and herpangina are the major clinical manifestations of enterovirus 71 (EV71) infections. Brain-stem encephalitis and pulmonary edema are severe complications that can lead to death. This study was designed to evaluate the potential therapeutic effect of milrinone, a phosphodiesterase (PDE) inhibitor, in the treatment of patients with EV71-induced pulmonary edema. We conducted a historically controlled trial of 24 children with severe EV71-induced pulmonary edema from April 1998-June 2003 in southern Taiwan. Patients were divided into groups treated before and after the introduction of milrinone therapy. Etiological diagnosis was established by viral cultures and confirmed by specific immunofluorescence and neutralization tests. All 24 patients were below 5 years of age. The mortality was lower in the milrinone-treated vs. nontreated group (36.4% vs. 92.3%, P=0.005). Sympathetic tachycardia was decreased in patients treated with milrinone compared to controls (144 +/- 17/min vs. 206 +/- 26/min, P=0.004). A marked decrease in IL-13 (77 +/- 9 pg/ml vs. 162 +/- 88 pg/ml, P=0.001) was observed in milrinone-treated patients compared to controls. There was a significant reduction in white blood cell (10,838 +/- 4,537/mm3 vs. 19,475 +/- 7,798/mm3, P=0.009) and platelet (257 +/- 45 x 10(3)/mm3 vs. 400 +/- 87 x 10(3)/mm3, P=0.001) counts in milrinone-treated patients compared to controls. These results were associated with improvement in sympathetic regulation and decrease in IL-13 production. Milrinone therapy may provide a useful therapeutic approach for this highly lethal disorder.

Human endothelial cell activation and apoptosis induced by enterovirus 71 infection

Enterovirus 71 (EV71), a neurotropic virus, its infection is transmitted mainly by the oral-fecal route. However, it is unclear how EV71 is disseminated/spread from initial replication sites to the central nervous system. Since endothelial cells form the interface between blood and tissues throughout the body, it is likely that EV71 can infect and then exit endothelial cells to establish infection. In this study, human endothelial cells were examined for susceptibility to EV71 infection using human microvascular endothelial cell line (HMEC-1 cell). Immunofluorescence assay confirmed EV71 infection of HMEC-1. Viable viruses were cultured from both the culture supernatant and the cell lysate. Live but not UV-inactivated EV71 induced HMEC-1 to secrete IL-6, macrophage migration inhibition factor, and macrophage chemo-attractant protein 1, and to express toll-like receptor 4. In addition, EV71 decreased the viability and increased the apoptosis of HMEC-1 cells after 36-48 hr of infection. These results demonstrate that EV71 is able to infect, activate, and induce apoptosis of endothelial cells, which may play a role in the pathogenesis of EV71 infection.

A mouse-adapted enterovirus 71 strain causes neurological disease in mice after oral infection

A mouse-adapted enterovirus 71 (EV71) strain with increased virulence in mice, MP4, was generated after four serial passages of the parental EV71 strain 4643 in mice. Strain MP4 exhibited a larger plaque size, grew more rapidly, and was more cytotoxic in vitro than strain 4643. Although strains 4643 and MP4 both induced apoptosis of SK-N-SH human neuroblastoma cells, MP4 was more virulent than 4643 in 1-day-old mice (50% lethal doses, 10(2) and 10(4) PFU/mouse, respectively). Strain MP4 (5 x 10(6) PFU/mouse), but not 4643, could orally infect 7-day-old mice, resulting in rear-limb paralysis followed by death 5 to 9 days after inoculation with the virus. Histopathologically, neuronal loss and apoptosis were evident in the spinal cords as well as the brain stems of the infected mice. The limb muscles displayed massive necrosis. There was early and transient virus replication in the intestines, whereas the spinal cord, brain, and muscle became the sites of viral replication during the late phase of the infection. Virus transmission occurred among infected and noninfected cagemates, as demonstrated by the occurrence of seroconversion and the presence of viable viruses in the stool samples of the latter. Protection against EV71 challenge was demonstrated following administration of hyperimmune serum 1 day after inoculation with the virus. Nucleotide sequence analysis of the genome of EV71 strain MP4 revealed four nucleotide changes on the 5' untranslated region, three on the VP2 region, and eight on the 2C region, resulting in one and four amino acid substitutions in the VP2 and 2C proteins, respectively.

Outcome of enterovirus 71 infections with or without stage-based management: 1998 to 2002

BACKGROUND

Enterovirus 71 (EV71) infection may progress through four stages, one of which is cardiopulmonary failure. In Taiwan in 1998 almost all the EV71 patients with cardiopulmonary failure died. To improve clinical outcome of EV71 patients, we developed a stage-based management program in 2000.

METHODS

The medical records of 196 EV71 patients who did not have stage-based management (1998 to 1999) and of 331 EV71 patients who did (2000 to 2002) at Chang Gung Children's Hospital were reviewed for demographic characteristics, clinical syndromes, case-fatality rates and sequelae. We compared and analyzed the results for the 2 groups.

RESULTS

Of the patients who did not receive stage-based management, 83% (15 of 18) of cases with both central nervous system (CNS) involvement and cardiopulmonary failure died during the acute stage of the infection. Two patients died at convalescence, and 1 had sequelae of dysphagia and limb weakness. By contrast of the patients who received stage-based management, 33% (12 of 36) of patients with CNS and cardiopulmonary failure died during the acute stage, 8% (3 of 36) died at convalescence, 14% (5 of 36) recovered and 43% (16 of 36) had severe sequelae of central hypoventilation, dysphagia and limb weakness (P < 0.001). For cases with CNS and cardiopulmonary failure, multivariate analysis showed that age older than 2 years and cerebro-spinal fluid white blood cell count >100/microl were associated with a increase in acute mortality [95% confidence interval (CI) 1.9 to 105.3, P = 0.001; 95% CI 1.1 to 66.6, P = 0.04, respectively], but stage-based management was significantly associated with a reduction in acute mortality (95% CI 0.007 to 0.24; P = 0.0004). Stage-based management did not affect the outcome of cases with CNS involvement alone.

CONCLUSIONS

Stage-based management reduced the case fatality rate of EV71-related cardiopulmonary failure, but two-thirds of the survivors had severe sequelae.

Infectious causes of acute flaccid paralysis

PURPOSE OF REVIEW

Although acute flaccid paralysis (AFP) is more frequently seen in the tropics than in temperate regions, recent outbreaks of West Nile virus (WNV) in North America have drawn attention to this important presentation. Starting with anatomical and neurophysiological considerations, this article examines data on AFP caused by WNV, and considers recent data on paralysis caused by enteroviruses, and Guillain-Barré syndrome (GBS).

RECENT FINDINGS

Neurophysiological, radiological and pathological studies suggest WNV causes AFP by damaging anterior horn cells in the spinal cord. The clinical presentation is probably best described as a 'poliomyelitis-like illness', and the disease as 'WNV myelitis'. Other findings during the recent outbreaks include increasing recognition of a Parkinson's-disease like presentation, and descriptions of virus transmission in blood transfusions and transplanted organs. GBS is now recognized as several disorders characterized by immune-mediated attack on peripheral nerves: in acute inflammatory demyelinating polyneuropathy the myelin sheath and Schwann cell of sensory and motor nerves are targeted; acute motor axonal and acute motor and sensory axonal neuropathy often follow Campylobacter jejuni enteritis and are associated with antibodies against the ganglioside component of the nerve axolemmal membrane. In Asia-Pacific, enterovirus 71 has caused outbreaks of neurological diseases with AFP and encephalitis, but no single genogroup of virus appears responsible for severe disease.

SUMMARY

Despite the near eradication of poliomyelitis, AFP caused by viruses remains an important clinical presentation. Distinguishing direct viral causes from GBS is important for public health reasons, and to avoid inappropriate therapies.

Transcranial Doppler sonography in the early stage of critical enteroviral infection

OBJECTIVE

There is a high fatality rate in enteroviral infection with central nervous system involvement. Our aim was to investigate the change in intracranial blood flow to disclose the characteristic findings in the early stage of critical enteroviral infection.

METHODS

We examined 27 patients in critical condition with enteroviral infection in our pediatric intensive care unit. We performed transcranial Doppler sonography within 12 hours of admission to the unit. The data were compared with those of a group of 11 patients with nonenteroviral encephalitis.

RESULTS

The peak systolic, end-diastolic, and mean velocities of the critical enteroviral infection group were significantly higher than those of the control group (P < .05). Gosling pulsatility index and Pourcelot resistive index values for the right and left middle cerebral arteries (pulsatility index, [mean +/- SD], 0.68 +/- 0.22 and 0.77 +/- 0.19, respectively; resistive index, 0.48 +/- 0.01 and 0.52 +/- 0.01) in patients with critical enteroviral infection were significantly lower than those of patients with nonenteroviral encephalitis (pulsatility index, 1.10 +/- 0.30 and 0.98 +/- 0.22; resistive index, 0.62 +/- 0.01 and 0.60 +/- 0.01; P < .05).

CONCLUSIONS

Low pulsatility index and resistive index values for cerebral blood flow were observed in the early stage of critical enteroviral infection. This characteristic finding of cerebral blood flow might be associated with the increased sympathetic discharge induced by a brain stem-involved systemic inflammatory response and dysfunction of autoregulation caused by the infection or other disorders of autoregulation that might cause severe or fatal complications.

Cardiac troponin I: a reliable marker and early myocardial involvement with meningoencephalitis after fatal enterovirus-71 infection

OBJECTIVES

A major outbreak of enterovirus 71 (EV71) in Taiwan in 1998 caused many severe cases and 78 deaths. Our purpose was to find reliable markers and early indicators of fatal EV71 central nervous system (CNS) infection.

METHODS

From June 2000 to November 2001, 21 patients with hand foot mouth disease or herpangina with CNS infection were admitted to Kaohsiung Veterans General Hospital. All 21 had culture-confirmed EV71 infection or were EV71 IgM positive. Patients were divided into two groups: group I included the five fatalities at our institution and group II, the 16 surviving patients.

RESULTS

Of the 21 infants and children with EV71 infection with CNS involvement, MR imaging studies were completed on 17, and 15 showed hyperintensity in the posterior portions of brain stem. All patients received intravenous immunoglobulin (IVIG) 1 g/day for two days and supportive care. Five patients rapidly deteriorated owing to irreversible hypotension and died. The other 16 patients recovered completely without sequel. In group I patients, the decrease of cardiac ejection function is significant and laboratory findings showed lower platelet count (P=0.0192). The mean of initial cTnI level for groups I and II was 10.6+/-11.6 and 0.48+/-0.55 ng/dl, respectively, higher in group I than in II (P=0.0019).

CONCLUSION

We hypothesized that like patients with severe burns, those with severe EV-71 CNS meningoencephalitis have varying degrees of non-ischemic cardiac injury, manifesting as leakage of cTnI from myocytes into the circulation. EV-71 CNS meningoencephalitis likely to die with an early myocardial involvement evidenced by reduced ejection fraction and release of cTnI. We conclude that fatal EV71 CNS infection quickly leads to death due to severe encephalopathy associated with cardiomyopathy.

Acute neurogenic pulmonary edema: case reports and literature review

Neurogenic pulmonary edema (NPE) is an underdiagnosed clinical entity. Its pathophysiology is multifactorial but largely unknown. We report two cases of NPE and review the literature on NPE cases reported since 1990. A 21-year-old man had a seizure episode following cranioplasty. He became increasingly dyspneic, and clinical and laboratory signs of respiratory failure were evident. Chest radiography and computed tomography showed bilateral diffuse infiltrates. After supportive measures were taken, complete respiratory recovery occurred in 72 hours. A 52-year-old woman had several seizure episodes following subarachnoid hemorrhage due to a cavernoma. She became increasingly dyspneic upon arrival at the hospital. After tracheostomy and oxygen support were established, chest radiography showed bilateral diffuse infiltrates. Respiratory recovery was excellent, and the patient was eupneic with normal results of chest radiography 48 hours later. Fourteen reports (21 cases) were found. Thirteen patients were female, and the mean age of the patients was 31.6 years. The most frequent underlying factor was subarachnoid hemorrhage (42.9%). Symptom onset occurred <4 hours after the neurologic event in 71.4% of cases. One third of the patients presented with pink frothy sputum. Chest radiography showed bilateral diffuse infiltrates in 90.5% of cases. Supportive measures included oxygen support and vasoactive drugs. Recovery was usually very rapid: 52.4% of patients recovered in <72 hours. Almost 10% of patients died of NPE. Our two cases had clinical and laboratory features in common with most NPE cases. Physicians should remember NPE when neurologic patients suddenly become dyspneic. The mortality rate is high, but surviving patients usually recover very quickly.

Pleconaril, a novel antipicornaviral agent

Despite the availability of therapy for selected symptoms, no specific antiviral agents are available to treat or prevent infections due to the viruses of the Picornaviridae family--rhinoviruses and enteroviruses. Characterization of the three-dimensional structure of picornaviruses in the 1980s allowed development of compounds targeted at the virus itself. Pleconaril is a novel, orally available, systemically acting molecule whose pharmacokinetics are characterized by a two-compartment open model with first-order absorption and with a safety profile similar to that of placebo. It shows promising results in treatment of picornaviral respiratory tract infections, meningitis, and other life-threatening infections.

Enterovirus 71 outbreaks, Taiwan: occurrence and recognition

Enterovirus 71 (EV71) caused a large outbreak in Taiwan in 1998 with 78 deaths, and smaller outbreaks recurred in 2000 and 2001. The outbreak was recognized because of a large number of hand, foot, and mouth disease cases and the rapid deaths of children with the disease. Virologic and pathologic studies indicated that EV71 was the most important agent related to severe and fatal cases and that a neurogenic inflammatory response was involved in the pathogenesis of cardiopulmonary collapse resulting from fulminant EV71 infection. Seroepidemiologic study suggested that EV71 had circulated for at least 16 years and that the accumulation of susceptible hosts might have triggered the 1998 outbreak. However, a change in EV71 neurovirulence and host genetic susceptibility may also have affected the clinical outcome. The Taiwan outbreak shows that worldwide attention should be paid to such outbreaks, new antiviral drugs should be developed, and that vaccination of children under 5 years of age may be warranted.

Proinflammatory cytokine reactions in enterovirus 71 infections of the central nervous system

Enterovirus 71 (EV71) infection can lead to devastating clinical outcomes. An appreciation of the scientific relationship between cytokine response and patient mortality may help limit the risks posed by this deadly illness. We present the results of a study that compared the cerebrospinal fluid (CSF) and serum levels of interleukin-6 (IL-6) and interleukin-1beta (IL-1beta) in 24 patients with EV71 infection. Cases in this study involved diverse manifestations or complications, including encephalitis, poliomyelitis-like syndrome, meningitis, and pulmonary edema. CSF levels of IL-6 in study patients were found to be consistently higher during the first 2 days of central nervous system (CNS) involvement than afterward. Compared with patients who did not have pulmonary edema, patients who experienced pulmonary edema had dramatically varied blood values, including IL-6, white blood cell counts, and glucose levels. Our findings suggest that the combination of CNS and systemic inflammatory response may trigger EV71-related cardiopulmonary collapse.