Fulminant neurogenic pulmonary oedema with hand, foot, and mouth disease

Genetic diversity of enterovirus 71 associated with hand, foot and mouth disease epidemics in Japan from 1983 to 2003

BACKGROUND

Enterovirus 71 (EV71) is one of the major etiologic agents of hand, foot and mouth disease (HFMD). The surveillance data indicate that EV71 infection follows an epidemic mode of transmission, causing large outbreaks and then becoming quiescent for a few years.

METHODS

We investigated the genetic diversity of a total of 121 EV71 strains isolated from patients with HFMD in Fukushima, Japan, from 1983 to 2003 and compared their genetic relation with the 164 EV71 strains isolated in the world using phylogenetic analysis based on the VP4 sequence.

RESULTS

We observed EV71-related HFMD outbreaks in Fukushima in 1984, 1987, 1990, 1993, 1997, 2000 and 2003. Phylogenetic reconstruction of EV71 strains isolated in Fukushima demonstrated 8 genetically distinct clusters, including 6 subgroups previously designated as B-1, B-2 and 3, B-4, C-1, C-2, and C-3 and 2 subgroups newly designated as B-5 and C-4. Additional 2 indistinct clusters belonged to genogroup C and were named C-U1 and C-U2. Of those subgroups, B-1, C-U1, C-U2, C-2, B4, and C-4 and B-5 dominantly related to epidemics that occurred in the years 1984, 1987 and 1990, 1993, 1997, 2000 and 2003, respectively. EV71 strains derived from each outbreak in Fukushima formed a single cluster with those isolated during almost the same time period in other area of Japan and in other countries.

CONCLUSIONS

Our results suggested that the repeated EV71 outbreaks might be the result of the worldwide transmission of the newly introduced genetically divergent EV71 strains.

N-acetylcysteine abrogates acute lung injury induced by endotoxin

1. Acute lung injury (ALI) or acute respiratory distress syndrome is a serious clinical problem with high mortality. N-Acetylcysteine (NAC) is an anti-oxidant and a free radical scavenger. It has been reported recently that NAC ameliorates organ damage induced by endotoxin (lipopolysaccharide; LPS) in conscious rats. The present study was designed to evaluate the effects of NAC on LPS-induced ALI and other changes in anaesthetized rats. 2. Sprague-Dawley rats were anaesthetized with pentobarbital (40 mg/kg, i.p.). Endotracheal intubation was performed to provide artificial ventilation. Arterial pressure and heart rate were monitored. The extent of ALI was evaluated with the lung weight (LW)/bodyweight ratio, LW gain, exhaled nitric oxide (NO) and protein concentration in bronchoalveolar lavage (PCBAL). Haematocrit, white blood cells, plasma nitrate/nitrite, methyl guanidine (MG), tumour necrosis factor (TNF)-alpha and interleukin (IL)-1b were measured. Pathological changes in the lung were examined and evaluated. 3. Endotoxaemia was produced by injection of 10 mg/kg, i.v., LPS (Escherichia coli). Animals were randomly divided into three groups. In the vehicle group, rats received an i.v. drip of physiological saline solution (PSS) at a rate of 0.3 mL/h. The LPS group received an i.v. drip of PSS for 1 h, followed by LPS (10 mg/kg by slow blous injection, i.v., over 1-2 min). Rats in the LPS + NAC group received NAC by i.v. drip at a rate of 150 mg/kg per h (0.3 mL/h) for 60 min starting 10 min before LPS administration (10 mg/kg by slow blous injection, i.v., over 1-2 min). Each group was observed for a period of 6 h. 4. N-Acetylcysteine treatment improved the LPS-induced hypotension and leukocytopenia. It also reduced the extent of ALI, as evidenced by reductions in LW changes, exhaled NO, PCBAL and lung pathology. In addition, NAC diminished the LPS-induced increases in nitrate/nitrite, MG, TNF-a and IL-1b. 5. In another series of experiments, LPS increased the mortality rate compared with the vehicle group (i.v. drip of PSS at a rate of 0.3 mL/h) during a 6 h observation period. N-Acetylcysteine, given 10 min prior to LPS, significantly increased the survival rate. 6. The results of the present study suggest that NAC exerts a protective effect on the LPS-induced ALI. The mechanisms of action may be mediated through the reduction of the production of NO, free radicals and pro-inflammatory cytokines.

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.

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.

Phosphorylation of PI3K/Akt and MAPK/ERK in an early entry step of enterovirus 71

Viruses have been known to subvert the anti-apoptotic pathways of the host cell in order to delay apoptosis. However, the mechanisms utilized by enterovirus 71 (EV71) to mediate anti-apoptotic activity remained undetermined. We observed that EV71 infection induced an early activation of both phosphatidylinositol 3-kinase (PI3K)/Akt and MAPK/ERK signaling pathways. The activity of GSK3β, a downstream target of these pathways, was negatively regulated by the activation of both MAPK/ERK and PI3K/Akt. The phosphorylation of GSK3 could be inhibited by treatment with the specific inhibitors of MAPK/ERK and PI3K/Akt. Other Akt downstream targets, BAD, caspase-9 and the Forkhead transcription factor (FKHR), were not phosphorylated during the course of infection by EV71. We further demonstrated that infection by UV-irradiated, inactivated virus triggered early Akt activation but was insufficient to trigger late Akt activation. These data suggest that with the phosphorylation of MAPK/ERK and PI3K/Akt the subsequent inactivation of GSK3β is utilized by EV71 as a potential mechanism to delay host cell apoptosis.

Predictors of unfavorable outcomes in enterovirus 71-related cardiopulmonary failure in children

BACKGROUND

Enterovirus 71 (EV71) can sometimes cause fatal or disabling diseases in children; therefore EV71-infected children with cardiopulmonary failure were investigated at Chang Gung Children's Hospital to discover the prognostic predictors.

METHODS

We investigated 27 EV71-infected children with cardiopulmonary failure from May 2000 to September 2001 and analyzed their clinical data to find predictors associated with unfavorable outcomes of deaths or ventilator dependence.

RESULTS

Of the 27 patients, 8 (30%) died and 10 (37%) were ventilator-dependent. Troponin I levels correlated most strongly with fatality, with 5 of the 6 children with troponin I levels >40 ng/ml dying (P = 0.001). Other factors correlated with fatality were cerebrospinal fluid white blood cell count > or =100/microL (P = 0.002) and initial systolic pressure < or =100 mm Hg (P = 0.05). Of the 19 survivors, 10 (53%) were left with central hypoventilation, dysphagia and/or limb weakness plus atrophy. The factors associated with ventilator dependence included higher inotrope equivalent (P < 0.001), duration of hypotension > or =40 hours, initial blood systolic pressure < or =100 mm Hg, positive EV71 isolation and age > or =12 months.

CONCLUSIONS

Poor prognostic factors were related to cardiovascular and neurologic damage; therefore physicians may consider advanced cardiovascular support for EV71-infected children with cardiopulmonary failure.

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.

Epidemiologic features of Kawasaki disease in Taiwan, 1996-2002

OBJECTIVE

Kawasaki disease (KD) is the most common acquired heart disease in children worldwide. The incidence of KD varies among different countries, with Asian countries supposedly having higher incidences than Western countries. However, the incidence of KD in Taiwan has not been well investigated.

METHODS

Since the implementation of Taiwan's National Health Insurance (NHI) in 1995, NHI has covered health care for >96% its population. Using the NHI database from 1996 to 2002, we investigated epidemiologic features of KD (International Classification of Diseases, Ninth Revision, code 446.1), the rate of coronary artery aneurysm formation (International Classification of Diseases, Ninth Revision, code 414.11), and the change in incidence during the recent 7 years. We also compared the annual incidences in Taiwan with those reported by other countries.

RESULTS

During the 7-year study period, KD occurred most frequently in the summer and least frequently in winter. It is interesting that the highest peak occurred in the summer of 1998 at the same time that Taiwan's enterovirus 71 epidemic was occurring. Ninety-one percent of KD cases occurred in children who were <5 years old, and the male-to-female ratio was 1.70:1. Recurrence of KD was found in 1.3% (94 of 7305) of these children, and coronary artery aneurysm was found in 7.3% (536 of 7305). The annual incidence per 100,000 children was 146 in children <1 year old, 98 in 1-year-old children, 51 in 2-year-old children, 28 in 3-year-old children, 19 in 4-year-old children, and 5.3 in 5- to 9-year-old children; the incidence of KD decreased with increased age. The overall incidence was 66 cases per 100,000 children <5 years old from 1996 to 2002 with the annual incidence not differing significantly during the 7-year study period.

CONCLUSIONS

KD in Taiwan occurs more frequently in boys and in the summer months. During the 7-year study period, the annual KD incidence in Taiwan of 66/100000 in children <5 years old was the second highest in the world after Japan.

Differential localization of neurons susceptible to enterovirus 71 and poliovirus type 1 in the central nervous system of cynomolgus monkeys after intravenous inoculation

Poliovirus and enterovirus 71 (EV71) are both neurotropic enteroviruses that cause serious neurological diseases, such as poliomyelitis and encephalitis. The neurovirulence of EV71 in cynomolgus monkeys was demonstrated previously by intraspinal inoculation. In this study, an improved simian model of EV71 infection was established by using intravenous inoculation, which revealed clinical and neuropathological similarities between this model and human cases of encephalitis. Experimental EV71 infection induced direct neurological manifestations, such as tremor, ataxia and brain oedema, but not non-neurological complications, such as pulmonary oedema and cardiac failure. Using this model of EV71 infection, the neurotropic characteristics of the prototype strains of EV71 and poliovirus type 1 (PV1) were compared. Three monkeys were inoculated intravenously with 10(5.5) TCID50 EV71 and all developed neurological disease signs within 4-6 days of inoculation. However, after inoculation with 10(5.5) TCID50 PV1 strain OM1 (PV1-OM1), the major manifestation was flaccid paralysis, starting from the lower limbs 6-9 days post-inoculation. Histopathological and virological analyses of moribund monkeys revealed that disseminated EV71 infection was characterized by severe panencephalitis involving both the pyramidal and extrapyramidal systems. In contrast, the lesions induced by PV1-OM1 were mainly restricted to the pyramidal tract, particularly the spinal motor neurons, thalamus and motor cortex. In conclusion, neuropathological involvement in this model correlated well with the apparent differences in neurological disease induced by EV71 and PV1-OM1. Thus, intravenous inoculation with EV71 is an excellent model to study the neuropathology of EV71 and to evaluate candidate vaccines and potential antiviral agents.

Mutation in enterovirus 71 capsid protein VP1 confers resistance to the inhibitory effects of pyridyl imidazolidinone

Enterovirus 71 is one of the most important pathogens in the family of Picornaviridae that can cause severe complications in the postpoliovirus era, such as encephalitis, pulmonary edema, and even death. Pyridyl imidazolidinone is a novel class of potent and selective human enterovirus 71 inhibitor. Pyridyl imidazolidinone was identified by using computer-assisted drug design. This virologic investigation demonstrates that BPR0Z-194, one of the pyridyl imidazolidinones, targets enterovirus 71 capsid protein VP1. Time course experiments revealed that BPR0Z-194 effectively inhibited virus replication in the early stages, implying that the compound can inhibit viral adsorption and/or viral RNA uncoating. BPR0Z-194 was used to select and characterize the drug-resistant viruses. Sequence analysis of the VP1 region showed that the resistant variants differed consistently by seven amino acids in VP1 region from their parental drug-sensitive strains. Site-directed mutagenesis of enterovirus 71 infectious cDNA revealed that a single amino acid alteration at the position 192 of VP1 can confer resistance to the inhibitory effects of BPR0Z-194.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) can be associated with various disorders. Among these, coronavirus infection may cause life-threatening severe acute respiratory syndrome (SARS). In this review, we present animal models and techniques for the study of ARDS, and discuss the roles and possible mechanisms of various chemical factors, including nitric oxide (NO). Our early work revealed that cerebral compression elicits severe hemorrhagic pulmonary edema (PE), leading to central sympathetic activation that results in systemic vasoconstriction. The consequence of systemic vasoconstriction is volume and pressure loading in the pulmonary circulation. Vasodilators, but not oxidant radical scavengers, are effective in the prevention of centrogenic PE. In isolated perfused lung, exogenous and endogenous NO enhances lung injury following air embolism and ischemia/reperfusion. In contrast, NO synthase (NOS) inhibitors reverse such lung injury. Although NO is important in maintaining vasodilator tone, hypoxia-induced pulmonary vasoconstriction is accompanied by an increase instead of a decrease in NO release. In animal and isolated lung studies, endotoxin produces acute lung injury that is associated with increases in cytokines and inducible NOS mRNA expression, suggesting that NO is toxic to the lung in endotoxin shock. Recently, we reported several rare cases that indicate that ARDS in patients with Japanese B encephalitis, lymphangitis with breast cancer and fat embolism is caused by different mechanisms. Our early and recent studies on ARDS and PE may provide information for clinical practice and the understanding of the pathogenesis of SARS.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) can be associated with various disorders. Among these, coronavirus infection may cause life-threatening severe acute respiratory syndrome (SARS). In this review, we present animal models and techniques for the study of ARDS, and discuss the roles and possible mechanisms of various chemical factors, including nitric oxide (NO). Our early work revealed that cerebral compression elicits severe hemorrhagic pulmonary edema (PE), leading to central sympathetic activation that results in systemic vasoconstriction. The consequence of systemic vasoconstriction is volume and pressure loading in the pulmonary circulation. Vasodilators, but not oxidant radical scavengers, are effective in the prevention of centrogenic PE. In isolated perfused lung, exogenous and endogenous NO enhances lung injury following air embolism and ischemia/reperfusion. In contrast, NO synthase (NOS) inhibitors reverse such lung injury. Although NO is important in maintaining vasodilator tone, hypoxia-induced pulmonary vasoconstriction is accompanied by an increase instead of a decrease in NO release. In animal and isolated lung studies, endotoxin produces acute lung injury that is associated with increases in cytokines and inducible NOS mRNA expression, suggesting that NO is toxic to the lung in endotoxin shock. Recently, we reported several rare cases that indicate that ARDS in patients with Japanese B encephalitis, lymphangitis with breast cancer and fat embolism is caused by different mechanisms. Our early and recent studies on ARDS and PE may provide information for clinical practice and the understanding of the pathogenesis of SARS.

Mechanism of fulminant pulmonary edema caused by enterovirus 71

Pulmonary edema (PE) may occur with enterovirus 71 (EV71) infection. We monitored arterial pressure (AP) and heart rate (HR) in patients with EV71 infection and analyzed the variability of AP and HR. Sympathetic activity, AP, and HR increased with respiratory stress. Thereafter, parasympathetic activity increased with decreases in AP and HR. The lungs showed edema with inducible nitric oxide synthase (iNOS) expression. Destruction of the medial, ventral, and caudal medulla may lead to sympathetic overactivation, causing blood to shift to the lungs. The pathogenesis of PE may also involve iNOS and nitric oxide.

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.

Neonatal enterovirus infections: emphasis on risk factors of severe and fatal infections

OBJECTIVES

Neonatal enterovirus infections have diverse manifestations, from asymptomatic to fatal. An understanding of the risk factors associated with severe cases might help to reduce enterovirus-related morbidity and mortality.

METHODS

From July 1989 through June 1998, neonates with virus culture-confirmed nonpolio enterovirus infection at Chang Gung Children's Hospital were enrolled in the study and divided into three groups: nonspecific febrile illness; aseptic meningitis; and hepatic necrosis with coagulopathy (HNC). Demographic factors, clinical manifestations, laboratory data and outcome were analyzed to reveal factors associated with clinical severity and fatality.

RESULTS

There were 146 cases including 43 neonates with nonspecific febrile illness, 61 with aseptic meningitis and 42 with HNC. By multiple logistic regression analysis, the most significant factors associated with HNC were prematurity, maternal history of illness, earlier age of onset (< or =7 days), higher white blood cell count (WBC > or =15 000/mm3) and lower hemoglobin (< or =10.7 g/dl). In 10 (24%) of 42 cases, HNC was fatal. In comparison with nonfatal cases of HNC, fatal cases had higher WBC, lower hemoglobin, higher bilirubin and higher incidence of concurrent myocarditis. Multivariate analysis showed the most significant factors associated with fatality from HNC to be total bilirubin >14.3 mg/dl (adjusted odds ratio, 29.1; 95% confidence interval, 2.5 to 355.5; P = 0.007) and concurrent myocarditis (adjusted odds ratio, 13.7; 95% confidence interval, 1.1 to 177.2; P = 0.04). Intravenous immunoglobulin did not correlate with clinical outcomes in cases with HNC.

CONCLUSIONS

Prematurity, maternal history of illness, earlier age of onset, higher WBC and lower hemoglobin are significant factors associated with HNC; higher total bilirubin and concurrent myocarditis were most significantly associated with fatality from HNC.

Neurogenic pulmonary edema in enterovirus 71 encephalitis is not uniformly fatal but causes severe morbidity in survivors

During the Australian summer of 2000/2001, there was an outbreak of enterovirus 71 infection in Sydney. Between December 2000 and May 2001, approximately 200 children presented to Sydney Children's Hospital with hand-foot-and-mouth disease and 18 experienced neurologic complications. Four presented with acute invasive central nervous system disease and severe pulmonary edema. We describe the cardiorespiratory disturbances and intensive care management of these four consecutive children successfully treated for neurogenic pulmonary edema attributed to proven enterovirus 71 infection. All four survived the acute stage of the illness. However, all four have been left with significant debilitating morbidity. Epidemic enterovirus 71 brainstem encephalitis presenting as neurogenic pulmonary edema can be successfully managed in the pediatric intensive care unit but has great potential to yield a large number of handicapped toddlers and become "the poliomyelitis of the 21st century."

Pulmonary edema of enterovirus 71 encephalomyelitis is associated with left ventricular failure: implications for treatment

Epidemics of enterovirus 71 infections caused the rapid death of many children in Malaysia in 1997 and in Taiwan in 1998. Pulmonary edema occurred in most of the fatal cases and was considered to be neurogenic. The role of the heart was rarely investigated before. Between January 1998-January 2001, 34 consecutive patients who were admitted to the intensive care unit due to enterovirus infection were studied prospectively. Patients were divided into two groups: group I with pulmonary edema, and group II without pulmonary edema. Comparisons were made between the two groups based upon demographic, neurological, and cardiovascular manifestations. Group I consisted of 11 patients (5 boys, 6 girls; mean age, 22.8 months), and group II of 23 patients (12 boys, 11 girls; mean age, 28.8 months). There were no significant differences between the two groups in comparing sex, age, body weight, neurological severity, intracranial pressure, cell count, protein and glucose levels in cerebral spinal fluid, and blood pressure. All group I patients had left ventricular dysfunction, and their ejection fractions were significantly lower than those of patients in group II (37 +/- 11% vs. 75 +/- 6%, P < 0.001). Group I heart rates were higher than those of group II (175 +/- 24 vs. 137 +/- 25, P < 0.001). In group I, 9 patients who received conventional treatment died, and the only two survivors received left ventricular assist devices. In conclusion, the pulmonary edema of fulminant enterovirus 71 infection is associated with left ventricular failure. Left ventricular function is the major determinant of outcome. Early recognition of heart failure and aggressive cardiac intervention are life-saving. Pediatr Pulmonol. 2003; 35:263-268.

Molecular epidemiology of human enterovirus 71 strains and recent outbreaks in the Asia-Pacific region: comparative analysis of the VP1 and VP4 genes

This study provides a comprehensive overview of the molecular epidemiology of human enterovirus 71 (HEV71) in the Asia-Pacific region from 1997 through 2002. Phylogenetic analysis of the VP4 and VP1 genes of recent HEV71 strains indicates that several genogroups of the virus have been circulating in the Asia-Pacific region since 1997. The first of these recent outbreaks, described in Sarawak (Malaysian Borneo) in 1997, was caused by genogroup B3. This outbreak was followed by large outbreaks in Taiwan in 1998, caused by genogroup C2, and in Perth (Western Australia) in 1999, where viruses belonging to genogroups B3 and C2 cocirculated. Singapore, Taiwan, and Sarawak had HEV71 epidemics in 2000, caused predominantly by viruses belonging to genogroup B4; however, large numbers of fatalities were observed only in Taiwan. HEV71 was identified during an epidemic of hand, foot and mouth disease in Korea; that epidemic was found to be due to viruses constituting a new genogroup, C3.

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.

Epidemic hand, foot and mouth disease caused by human enterovirus 71, Singapore

Singapore experienced a large epidemic of hand, foot and mouth disease (HFMD) in 2000. After reviewing HFMD notifications from doctors and child-care centers, we found that the incidence of HFMD rose in September and declined at the end of October. During this period, 3,790 cases were reported. We performed enteroviral cultures on 311 and 157 specimens from 175 HFMD patients and 107 non-HFMD patients, respectively; human enterovirus 71 (HEV71) was the most frequently isolated virus from both groups. Most of the HFMD patients were <4 years of age. Three HFMD and two non-HFMD patients died. Specimens from two HFMD and both non-HFMD patients were culture positive for HEV71; a third patient was possibly associated with the virus. Autopsies performed on all three HFMD and one of the non-HFMD case-patients showed encephalitis, interstitial pneumonitis, and myocarditis. A preparedness plan for severe HFMD outbreaks provided for the prompt, coordinated actions needed to control the epidemic.

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.

Epidemic hand, foot and mouth disease caused by human enterovirus 71, Singapore

Singapore experienced a large epidemic of hand, foot and mouth disease (HFMD) in 2000. After reviewing HFMD notifications from doctors and child-care centers, we found that the incidence of HFMD rose in September and declined at the end of October. During this period, 3,790 cases were reported. We performed enteroviral cultures on 311 and 157 specimens from 175 HFMD patients and 107 non-HFMD patients, respectively; human enterovirus 71 (HEV71) was the most frequently isolated virus from both groups. Most of the HFMD patients were </=4 years of age. Three HFMD and two non-HFMD patients died. Specimens from two HFMD and both non-HFMD patients were culture positive for HEV71; a third patient was possibly associated with the virus. Autopsies performed on all three HFMD and one of the non-HFMD case-patients showed encephalitis, interstitial pneumonitis, and myocarditis. A preparedness plan for severe HFMD outbreaks provided for the prompt, coordinated actions needed to control the epidemic.

Laboratory diagnosis and genetic analysis of an echovirus 30-associated outbreak of aseptic meningitis in Taiwan in 2001

A large outbreak of aseptic meningitis occurred from April to November 2001 in Taiwan. Of the 1,130 enterovirus-infected patients, echovirus 30 (E30) infection was diagnosed in 188 (16.6%), with the patients having various clinical manifestations including aseptic meningitis (73.9%), young infant fever (6.9%), respiratory symptoms or herpangina (13.3%), or others (5.9%). The majority of the E30-infected patients were between 3 and 10 years old. Of the 264 E30 strains identified, 94.3, 71, and 67.4% were isolated from RD, MRC-5, and A549 cells, respectively. Primary isolation of E30 required mean times of 3.7 days for RD cells and 4.1 days for MRC-5 and A549 cells. Among all E30-positive patients, virus was most frequently isolated from throat swab specimens (85.2%) and, to a lesser extent, stool (76.4%) or cerebrospinal fluid (70.1%) specimens. The virus isolates were initially identified as echovirus 4 (E4) on the basis of immunofluorescence staining with anti-E4 and anti-E30 (Bastianni prototype) monoclonal antibodies. However, upon performance of the neutralization test, E30-specific reverse transcription-PCR, and sequencing of the VP1 gene, the results identified these isolates as E30, not E4, indicating that the reagent used to type E30, which is produced with the Bastianni strain as the immunogen, is inadequate for the identification of recent E30 isolates in Taiwan. Phylogenetic analyses of the VP1 genes of these isolates showed that their sequences differed from those of E30 isolates from the GenBank database by 9.1 to 25.2%, suggesting that this outbreak was caused by a new variant strain of E30 introduced into Taiwan in 2000 that resulted in the widespread aseptic meningitis epidemic in 2001.

Risk factors of enterovirus 71 infection and associated hand, foot, and mouth disease/herpangina in children during an epidemic in Taiwan

OBJECTIVE

In 1998, an enterovirus 71 (EV71) epidemic in Taiwan was associated with hand, foot, and mouth disease (HFMD)/herpangina and involved 78 fatal cases. We measured EV71 seroprevalence rates before and after the epidemic and investigated risk factors associated with EV71 infection and illness.

METHODS

Neutralizing antibodies to EV71 were assayed for 539 people before the epidemic and 4619 people of similar ages after the epidemic. Questionnaires, which were completed during household interviews after the epidemic, solicited demographic variables, exposure history, and clinical manifestations.

RESULTS

A total of 129 106 cases of HFMD were reported during the epidemic. Age-specific pre-epidemic EV71 seroprevalence rates were inversely related to age-specific periepidemic mortality rates (r = -0.82) or severe case rates (r = -0.93). Higher postepidemic EV71 seropositive rates among children who were younger than 3 years positively correlated with higher mortality rates in different areas (r = 0.88). After the epidemic, 51 (56%) of 91 younger siblings of elder siblings who were EV71-seropositive were EV71-seropositive; otherwise, 2.2% (4 of 186) of younger siblings were EV71-seropositive (matched odds ratio [OR]: 10; 95% confidence interval [CI]: 3.4-29). Stepwise multiple logistic regression revealed other factors associated with EV71 infection to be older age (adjusted OR: 2.5; 95% CI: 1.9-3.4), attendance at kindergartens/child care centers (adjusted OR: 1.8; 95% CI: 1.3-2.5), contact with HFMD/herpangina (adjusted OR: 1.6; 95% CI: 1.2-2.1), greater number of children in a family (adjusted OR: 1.4; 95% CI: 1.1-1.7), and rural residence (adjusted OR: 1.4; 95% CI: 1.2-1.6). Twenty-nine percent of preschool children who were infected with EV71 developed HFMD/herpangina. Younger age and contact with HFMD/herpangina were significant factors for the development of EV71-related HFMD/herpangina in these children.

CONCLUSIONS

An increased incidence of EV71 infection in young children occurred more often in geographic areas with increased mortality rates. Intrafamilial and kindergarten transmissions among preschool children were major modes of disease transmission during the widespread EV71 epidemic in Taiwan in 1998.

Incidence and case-fatality rates resulting from the 1998 enterovirus 71 outbreak in Taiwan

In 1998, an epidemic of hand-foot-and-mouth disease and herpangina caused by enterovirus 71 occurred in Taiwan, leaving many fatalities and severely handicapped survivors in its wake. The reasons this rather common pathogen would cause such a large-scale epidemic remain unknown. A seroepidemiological survey to elucidate the epidemiological characteristics of this outbreak, including its incidence and case-fatality rates was undertaken. Microneutralization tests for antibodies against enterovirus 71 were used to screen four collections of serum samples: 1) 202 specimens taken from individuals > or = 4 years old in 1994; 2) 245 specimens collected from individuals of all ages in 1997; 3) 1,258 specimens collected from individuals of all ages in 1999; and 4) sera samples from a birth cohort of 81 children who had yearly blood samples taken from 1988-98. After the maternal antibody had declined, the seropositive rates began to increase with age. Approximately half of all children aged 6 years or older were enterovirus 71 seropositive. Significantly higher seropositive rates were noted in 1999 than in 1997, in children aged 0.5-3 years. The incidence of enterovirus 71 infection during the epidemic was estimated to be 13-22%, with the higher rates in younger children. The case-fatality rate was highest (96.96 per 100,000) in infants aged 6-11 months, and declined in older children. The results showed that enterovirus 71 is endemic in Taiwan. The apparent lack of large-scale enterovirus 71 activity in the 3 years before 1998 might have been the prelude to the epidemic's appearance in 1998, and might suggest that enterovirus 71 infection will reappear every few years. The lack of a protective antibody in younger children may account for the high incidence and case-fatality rate in this age group.

Infection with enterovirus 71 or expression of its 2A protease induces apoptotic cell death

Enterovirus 71 (EV71) is the causative agent of human diseases with distinct severity, from mild hand-foot-and-mouth disease to severe neurological syndromes, such as encephalitis and meningitis. Infection of several different cell lines with EV71 causes extensive cytopathic effect, leading to destruction of the entire monolayer and the death of infected cells. In this study, cell death processes during EV71 infection and the underlying mechanisms of them were investigated. The hallmarks of apoptosis, nuclear condensation and fragmentation, were observed 24 h after infection. Apoptosis in infected cells was also confirmed by detectable cleavage of cellular DNA and degradation of poly(ADP-ribose) polymerase. Transient expression of EV71 2A protease (2A(pro)) alone resulted in the induction of apoptotic change. Infection of EV71 or expression of EV71 2A(pro) leads to cleavage of the eukaryotic initiation factor 4GI, a key factor for host protein synthesis. This study added one more example to the growing list of human viruses that induce apoptosis by a virus-encoded protein.

Pyramidal and extrapyramidal involvement in experimental infection of cynomolgus monkeys with enterovirus 71

Among the enteroviruses, polioviruses and enterovirus 71 (EV71) are two major neurotropic viruses causing serious neurological manifestations. While polioviruses are being eradicated globally by vaccination, EV71 still has the potential to cause a large outbreak such as that in Taiwan in 1998, in which there were many fatalities. In this study, we determined the neurovirulence of EV71 by neuropathological analysis of cynomolgus monkeys after experimental infection with five EV71 strains, which were isolated from individual patients with fatal encephalitis; meningitis; and hand, foot, and mouth disease. After intraspinal inoculation, the monkeys developed neurological manifestations within 1-6 days post-inoculation, irrespective of the inoculated strains. These manifestations included not only pyramidal tract signs such as flaccid paralysis, but also extrapyramidal tract signs such as tremor and ataxia. Histological and viral examinations confirmed virus replication in the spinal cord, brainstem, cerebellar cortex, and dentate nuclei, and cerebrum. The strains isolated during the 1970s and 1990s showed no particular differences with respect to neurotropism. Thus, it is clear that EV71 has a wider neurotropism than that of polioviruses.

Molecular classification of enteroviruses not identified by neutralization tests

We isolated six viruses from patients diagnosed with aseptic meningitis or hand, foot, and mouth disease. The cytopathic effect of these viruses on cultured cells was like that of enteroviruses. However, viral neutralization tests against standard antisera were negative. Phylogenetic analysis with the complete VP4 nucleotide sequences of these 6 viruses and 29 serotypes of enteroviruses classified 3 of the viruses as serotype echovirus type 18 (EV18) and 3 as serotype human enterovirus 71 (HEV71). These results were confirmed by remicroneutralization tests with HEV-monospecific antisera or an additional phylogenetic analysis with the complete VP4 nucleotide sequences. Phylogenetic analysis with complete VP4 genes is more useful than neutralization tests with enterovirus serotype-specific antisera in identifying enterovirus serotypes.

An overview of the evolution of enterovirus 71 and its clinical and public health significance

Since its discovery in 1969, enterovirus 71 (EV71) has been recognised as a frequent cause of epidemics of hand-foot-and-mouth disease (HFMD) associated with severe neurological sequelae in a small proportion of cases. There has been a significant increase in EV71 epidemic activity throughout the Asia-Pacific region since 1997. Recent HFMD epidemics in this region have been associated with a severe form of brainstem encephalitis associated with pulmonary oedema and high case-fatality rates. The emergence of large-scale epidemic activity in the Asia-Pacific region has been associated with the circulation of three genetic lineages that appear to be undergoing rapid evolutionary change. Two of these lineages (B3 and B4) have not been described previously and appear to have arisen from an endemic focus in equatorial Asia, which has served as a source of virus for HFMD epidemics in Malaysia, Singapore and Australia. The third lineage (C2) has previously been identified [Brown, B.A. et al. (1999) J. Virol. 73, 9969-9975] and was primarily responsible for the large HFMD epidemic in Taiwan during 1998. As EV71 appears not to be susceptible to newly developed antiviral agents and a vaccine is not currently available, control of EV71 epidemics through high-level surveillance and public health intervention needs to be maintained and extended throughout the Asia-Pacific region. Future research should focus on (1) understanding the molecular genetics of EV71 virulence, (2) identification of the receptor(s) for EV71, (3) development of antiviral agents to ameliorate the severity of neurological disease and (4) vaccine development to control epidemics. Following the successful experience of the poliomyelitis control programme, it may be possible to control EV71 epidemics if an effective live-attenuated vaccine is developed.

The 3C protease activity of enterovirus 71 induces human neural cell apoptosis

The human glioblastoma SF268 cell line was used to investigate the induction of apoptosis by the 3C protease of enterovirus 71 (EV71). Transient expression in these cells of the wild-type 3C protein encoded by EV71 induced morphological alterations typical of apoptosis, including generation of apoptotic bodies. Degradation of cellular DNA in nucleosomes was also observed. When two of the amino acids in the catalytic motif of 3C were changed by mutagenesis, the 3C protein not only lost its proteolytic activity, but also its ability to induce apoptosis in the SF268 cells. Twenty-four hours after 3C transfection, poly(ADP-ribose) polymerase, a DNA repair enzyme, was cleaved, indicating that caspases were activated by the expression of EV71 3C. The 3C-induced apoptosis was blocked by the caspase inhibitors DEVD-fmk and VAD-fmk. Our findings suggest that the proteolytic activity of 3C triggers apoptosis in the SF268 cells through a mechanism involving caspase activation and that this apoptotic pathway may play an important role in the pathogenesis of EV71 infection.

Phylogenetic analysis of enterovirus 71 strains isolated during linked epidemics in Malaysia, Singapore, and Western Australia

Enterovirus 71 (EV71) is a frequent cause of hand, foot, and mouth disease (HFMD) epidemics associated with severe neurological sequelae in a small proportion of cases. There has been a significant increase in EV71 epidemic activity throughout the Asia-Pacific region since 1997. Recent HFMD epidemics in this region have been associated with a severe form of brainstem encephalitis associated with pulmonary edema and high case fatality rates. In this study, we show that four genetic lineages of EV71 have been prevalent in the Asia-Pacific region since 1997, including two previously undescribed genogroups (B3 and B4). Furthermore, we show that viruses belonging to genogroups B3 and B4 have circulated endemically in Southeast Asia during this period and have been the primary cause of several large HFMD or encephalitis epidemics in Malaysia, Singapore, and Western Australia.

Pathologic studies of fatal cases in outbreak of hand, foot, and mouth disease, Taiwan

In 1998, an outbreak of enterovirus 71-associated hand, foot, and mouth disease occurred in Taiwan. Pathologic studies of two fatal cases with similar clinical features revealed two different causative agents, emphasizing the need for postmortem examinations and modern pathologic techniques in an outbreak investigation.

Emerging viral diseases of Southeast Asia and the Western Pacific

Over the past 6 years, a number of zoonotic and vectorborne viral diseases have emerged in Southeast Asia and the Western Pacific. Vectorborne disease agents discussed in this article include Japanese encephalitis, Barmah Forest, Ross River, and Chikungunya viruses. However, most emerging viruses have been zoonotic, with fruit bats, including flying fox species as the probable wildlife hosts, and these will be discussed as well. The first of these disease agents to emerge was Hendra virus, formerly called equine morbillivirus. This was followed by outbreaks caused by a rabies-related virus, Australian bat lyssavirus, and a virus associated with porcine stillbirths and malformations, Menangle virus. Nipah virus caused an outbreak of fatal pneumonia in pigs and encephalitis in humans in the Malay Peninsula. Most recently, Tioman virus has been isolated from flying foxes, but it has not yet been associated with animal or human disease. Of nonzoonotic viruses, the most important regionally have been enterovirus 71 and HIV.

Neutralizing antibody provided protection against enterovirus type 71 lethal challenge in neonatal mice

Experimental infection with enterovirus type 71 (EV71) induced death in neonatal mice in an age- and dose-dependent manner. The mortality rate was 100% following intraperitoneal inoculation 1-day-old ICR mice and this gradually decreased as the age at the time of inoculation increased (60% in 3-day-old mice and no deaths occurred in mice older than 6 days of age). A lethal dose greater than 10(8) PFU was necessary. Lethargy, failure to gain weight, rear limb tremors and paralysis were observed in the infected mice before death. EV71 was isolated from various tissues of the dead mice. Using a reverse transcription polymerase chain reaction technique with a specific primer pair, a 332-bp product was detected in the tissues that produced a culture positive for EV71. Protection against EV71 challenge in neonatal mice was demonstrated following passive transfer of serum from actively immunized adult mice 1 day after inoculation with the virus. Pups from hyperimmune dams were resistant to EV71 challenge. Additionally, maternal immunization with a formalin-inactivated whole-virus vaccine prolonged the survival of pups after EV71 lethal challenge.

Acute encephalomyelitis during an outbreak of enterovirus type 71 infection in Taiwan: report of an autopsy case with pathologic, immunofluorescence, and molecular studies

We report a fatal case of enterovirus type 71 (EV 71) infection in an 8-year-old girl during a summer outbreak of hand, foot, and mouth disease in 1998 in Taiwan. The clinical course was rapidly progressive, with manifestations of hand, foot, and mouth disease, aseptic meningitis, encephalomyelitis, and pulmonary edema. The patient died 24 hours after admission. Postmortem study revealed extensive inflammation in the meninges and central nervous system and marked pulmonary edema with focal hemorrhage. Brain stem and spinal cord were most severely involved. The inflammatory infiltrates consisted largely of neutrophils involving primarily the gray matter with perivascular lymphocytic cuffing, and neuronophagia. The lungs and heart showed no evidence of inflammation. EV 71 was isolated from the fresh brain tissues and identified by immunofluorescence method with type-specific EV 71 monoclonal antibody. It was also confirmed by neutralization test and reverse-transcriptase polymerase chain reaction with sequence analysis. The present case was the first example in which EV 71 was demonstrated to be the causative agent of fatal encephalomyelitis during its epidemic in Taiwan.

Deaths of children during an outbreak of hand, foot, and mouth disease in sarawak, malaysia: clinical and pathological characteristics of the disease. For the Outbreak Study Group

From April through June 1997, 29 previously healthy children aged <6 years (median, 1.5 years) in Sarawak, Malaysia, died of rapidly progressive cardiorespiratory failure during an outbreak of hand, foot, and mouth disease caused primarily by enterovirus 71 (EV71). The case children were hospitalized after a short illness (median duration, 2 days) that usually included fever (in 100% of case children), oral ulcers (66%), and extremity rashes (62%). The illness rapidly progressed to include seizures (28%), flaccid limb weakness (17%), or cardiopulmonary symptoms (of 24 children, 17 had chest radiographs showing pulmonary edema, and 24 had echocardiograms showing left ventricular dysfunction), resulting in cardiopulmonary arrest soon after hospitalization (median time, 9 h). Cardiac tissue from 10 patients showed normal myocardium, but central nervous system tissue from 5 patients showed inflammatory changes. Brain-stem specimens from 2 patients were available, and both specimens showed extensive neuronal degeneration, inflammation, and necrosis, suggesting that a central nervous system infection was responsible for the disease, with the cardiopulmonary dysfunction being neurogenic in origin. EV71 and possibly an adenovirus, other enteroviruses, or unknown cofactors are likely responsible for this rapidly fatal disease.

An outbreak of enterovirus 71 infection in Taiwan, 1998. II. Laboratory diagnosis and genetic analysis

BACKGROUND

An epidemic of enterovirus 71 (EV71) occurred in Taiwan from April to December of 1998, with two peaks, one in June and the other in October. Many enteroviruses were isolated in our laboratory from 258 cases during this outbreak. Approximately half of the enteroviruses isolated were EV71 and one fifth were coxsackievirus A16.

OBJECTIVES

To analyze laboratory findings in the EV71 epidemic of 1998 in Taiwan, various EV71 specimens in different cell lines were examined. In addition, genetic analysis of 5' non-coding region (NCR) was performed to analyze the strain variation in this outbreak.

RESULTS

The cytopathic effect induced by EV71 was observed 2-13 (mean of 4.5) days post-inoculation in Vero cells and 4-15 (mean of 6.6) days in green monkey kidney (GMK) cells inoculated with throat swabs. Of the total positive EV71 cases, virus was most frequently obtained from throat swabs (91.7%), less from stools (64.8%), and none from cerebral spinal fluid (CSF). Molecular analyses of EV71 by sequencing the 5' NCR of 34 strains obtained from different clinical categories and various geographic areas showed that their sequences differed (0-13 bp in 681 bp sequenced) by approximately 0-2%. The sequences of these isolates differed from EV71 prototype BrCr or MS strain by 17.5-19%, with the exception of two samples which exhibited nucleotide variation by only 8.9 and 8.2%, when compared to the MS strain.

CONCLUSION

EV71 was most frequently isolated from throat swab specimens in Vero cells. The molecular analyses of the 5' NCR of EV71 revealed that most isolates from this epidemic belonged to a group of closely related clones and only two were in a different group which was clustered with the EV71 MS strain.

Congenital enterovirus 71 infection: a case study with virology and immunohistochemistry

Previously reported enterovirus 71 (EV71) infections associated with hand-foot-mouth disease, aseptic meningitis, encephalitis, polio-like myelitis, and paralysis all have involved young children. We report a 28-year-old woman who possibly contracted EV71 infection during pregnancy. Obstetric ultrasonograms at 25 weeks of gestation revealed an abnormal placenta, as well as hepatosplenomegaly, liver calcification, excessive ascites, and mild hydrocephalus of the fetus. Presence of EV71 was determined by immunodot blotting, virus culture, and partial sequencing of the amplified product of nested reverse transcription-polymerase chain reaction. Postmortem immunohistochemistry further identified EV71 in the fetal midbrain and liver. The findings indicate that intrauterine EV71 infection is possible during pregnancy.

Genetic analysis of enterovirus 71 isolated from fatal and non-fatal cases of hand, foot and mouth disease during an epidemic in Taiwan, 1998

A large scale outbreak of hand-foot-and-mouth disease (HFMD) occurred in Taiwan in 1998, in which more than 80 children died of shock syndrome with pulmonary edema/hemorrhage. Enterovirus 71 was implicated as the cause of this outbreak. In order to understand the virological basis responsible for mortality on this scale, nucleotide sequences of VP1 that is important for serotypic specificity, and the 5'-non-coding region (5'-NCR) that is important for replication efficiency, were analyzed comparatively. Phylogenetic analysis of both VP1 and 5'-NCR of nine EV71 isolates derived from specimens of fatal patients and seven isolates derived from uncomplicated HFMD patients showed that all but one isolate fell into genotype B. The one distinct isolate from a case of uncomplicated HFMD belonged to genotype C that was clustered along with one isolate from Taiwan in 1986. Complete sequence analysis of two selected isolates, one from the spinal cord of a fatal case and one from the vesicle fluid of a patient with mild HFMD, confirmed a high degree (97-100%) of identity in nucleotide sequence throughout the entire genome, except focal regions of 3C and 3'-NCR where the nucleotide homology was 90-91%. The identity of the deduced amino acid sequence in the 3C region that encodes viral proteinase dropped further to 86%, a result of missense mutations at the first nucleotide position of many codons.

Expression of capsid [correction of caspid] protein VP1 for use as antigen for the diagnosis of enterovirus 71 infection

To produce enterovirus 71 antigen for diagnostic purposes, the gene encoding the entire capsid protein VP1 was amplified by reverse transcription-polymerase chain reaction (RT-PCR), cloned and expressed in Escherichia coli as a poly-histidine fusion protein. Western blotting experiments with sera from patients with enterovirus 71 infection indicated that immunoglobulin G (IgG) and IgM antibodies bound to a single polypeptide VP1. According to these results, IgM anti-VP1 appeared in sera of patients with a symptomatic enterovirus 71 acute infection, whereas IgG anti-VP1 was present in sera of past infection. This finding suggests that detecting IgG and IgM immune responses against linear epitopes of recombinant VP1 is an effective means of determining the different phases of enterovirus 71 infection. In addition, sera containing coxsackie virus 16 (CA16) antibodies did not cross-react with the recombinant VP1 of enterovirus 71, despite the homology between VP1 proteins of both viruses. Comparison with reference PCR and neutralization assays showed these antibody tests to be appropriate for the serodiagnosis of enterovirus 71 infection.

Serotype-specific identification of enterovirus 71 by PCR

BACKGROUND

Enterovirus 71 and coxsackievirus A16 are closely related genetically and are causative agents of hand foot and mouth disease. Because enterovirus 71 is more often associated with severe neurological disease, there is a need to rapidly discriminate between enterovirus 71 and coxsackievirus A16 during hand, foot, and mouth disease outbreaks.

OBJECTIVES

Our goal was to develop and evaluate a serotype-specific reverse transcription-polymerase chain reaction (RT/PCR)-based typing method for enterovirus 71.

STUDY DESIGN

Two sets of PCR primers were designed to match conserved amino acid intervals of enterovirus 71. One diagnostic primer pair contains deoxyinosine at sites of 4-fold codon degeneracy. A second primer pair was designed for use in sequencing and molecular epidemiology studies. Primer pairs were tested on strains encountered in routine diagnostic samples.

RESULTS

Using both sets of primers on a panel of 61 prototype enteroviral strains, both primer pairs gave strong positive signals for only enterovirus 71. These primers amplified all enterovirus 71 isolates tested and discriminated between enterovirus 71 and the most closely related enterovirus, coxsackievirus A16.

CONCLUSIONS

Our RT-PCR assay can be used for specific identification of enterovirus 71 clinical isolates. Furthermore, the 484-bp product of one primer pair has proven useful in sequencing studies to identify distinct genotypes of enterovirus 71.

Molecular epidemiology and evolution of enterovirus 71 strains isolated from 1970 to 1998

Enterovirus 71 (EV71) (genus Enterovirus, family Picornaviridae), a common cause of hand, foot, and mouth disease (HFMD), may also cause severe neurological diseases, such as encephalitis and poliomyelitis-like paralysis. To examine the genetic diversity and rate of evolution of EV71, we have determined and analyzed complete VP1 sequences (891 nucleotides) for 113 EV71 strains isolated in the United States and five other countries from 1970 to 1998. Nucleotide sequence comparisons demonstrated three distinct EV71 genotypes, designated A, B, and C. The genetic variation within genotypes (12% or fewer nucleotide differences) was less than the variation between genotypes (16.5 to 19.7%). Strains of all three genotypes were at least 94% identical to one another in deduced amino acid sequence. The EV71 prototype strain, BrCr-CA-70, isolated in California in 1970, is the sole member of genotype A. Strains isolated in the United States and Australia during the period from 1972 to 1988, a 1994 Colombian isolate, and isolates from a large HFMD outbreak in Malaysia in 1997 are all members of genotype B. Although strains of genotype B continue to circulate in other parts of the world, none have been isolated in the United States since 1988. Genotype C contains strains isolated in 1985 or later in the United States, Canada, Australia, and the Republic of China. The annual rate of evolution within both the B and C genotypes was estimated to be approximately 1.35 x 10(-2) substitutions per nucleotide and is similar to the rate observed for poliovirus. The results indicate that EV71 is a genetically diverse, rapidly evolving virus. Its worldwide circulation and potential to cause severe disease underscore the need for additional surveillance and improved methods to identify EV71 in human disease.

Comparison of enterovirus 71 and coxsackie-virus A16 clinical illnesses during the Taiwan enterovirus epidemic, 1998

OBJECTIVES

To compare enterovirus 71 (EV 71) with coxsackievirus A16 (Cox A16) clinical illness in patients at Chang Gung Children's Hospital during Taiwan's enterovirus epidemic of 1998.

METHODS

With the use of the immunofluorescence assay and neutralization test, 177 cases of EV 71 and 64 cases of Cox A16 illness were confirmed from April to September, 1998. The clinical signs and symptoms, complications and case fatality rates were compared.

RESULTS

Three-fourths of the cases were younger than 3 years of age, and the ratio of males to females was 1.3 in the EV 71 group and 1.2 in the Cox A16 group. In the EV 71 group 120 (68%) cases were uncomplicated, including 94 cases of hand, foot and mouth disease and 15 cases of herpangina, and 57 (32%) cases had complications, including 13 (7.3%) cases of aseptic meningitis, 18 (10%) cases of encephalitis, 4 (2.3%) cases of polio-like syndrome, 8 (4.5%) cases of encephalomyelitis and 12 (6.8%) cases of fatal pulmonary edema. Fourteen (7.9%) patients died, including 12 cases of pulmonary edema and 2 cases of encephalitis; seven (4%) patients had sequelae. By contrast, 60 (94%) of the 64 cases of Cox A16 infection were uncomplicated and only 4 (6.3%) cases were complicated by aseptic meningitis; no fatalities or sequelae were observed. By multivariate analysis vomiting (P = 0.01) and fever higher than 39 degrees C plus lasting longer than 3 days (P = 0.02) were significantly more frequent in the EV 71 group.

CONCLUSION

EV 71 illness is more severe with significantly greater frequency of serious complications and fatality than is illness caused by Cox A16.

Clinical features and risk factors of pulmonary oedema after enterovirus-71-related hand, foot, and mouth disease

BACKGROUND

In Taiwan, from April to July, 1998, an epidemic of hand, foot, and mouth disease associated with enterovirus 71 (EV71) occurred with fatal complications. We did a clinical study of EV71-related diseases in Taiwan.

METHODS

We studied 154 children with virus-culture confirmed EV71 infection. Children were divided into three groups: 11 patients with pulmonary oedema; 38 patients with central nervous system (CNS) involvement and no pulmonary oedema; and 105 children without complications. We compared the clinical features, laboratory findings, risk factors, and outcome among these three groups.

FINDINGS

Nine children with pulmonary oedema had hand, foot, and mouth disease, one had herpangina, and one had febrile illness with eight children with limb weakness and one with limb hypesthesia. All children had had sudden onset of tachycardia, tachypnoea, and cyanosis 1-3 days after onset of the disease. Nine of 11 children died within 12 h of intubation; one child was braindead within 15 h and died 17 days after intubation; one child was in deep coma and died 3 months later. In children with CNS complication and no pulmonary oedema, one child died of pneumonia after 4 months of ventilator support and four children had sequelae. All 105 children without complications recovered. There was a significant association between CNS involvement and pulmonary oedema (odds ratio 12.4 [95% CI 2.6-60.1], p=0.001). Risk factors for pulmonary oedema after CNS involvement were hyperglycaemia, leucocytosis, and limb weakness. Hyperglycaemia was the most significant prognostic factor for pulmonary oedema (odds ratio 21.5 [3-159], p=0.003).

INTERPRETATION

EV71 can cause hand, foot, and mouth disease, CNS involvement with severe sequelae, and fatal pulmonary oedema. Hyperglycaemia is the most important prognostic factor.

Neurologic complications in children with enterovirus 71 infection

BACKGROUND

Enterovirus 71 infection causes hand-foot-and-mouth disease in young children, which is characterized by several days of fever and vomiting, ulcerative lesions in the oral mucosa, and vesicles on the backs of the hands and feet. The initial illness resolves but is sometimes followed by aseptic meningitis, encephalomyelitis, or even acute flaccid paralysis similar to paralytic poliomyelitis.

METHODS

We describe the neurologic complications associated with the enterovirus 71 epidemic that occurred in Taiwan in 1998. At three major hospitals we identified 41 children with culture-confirmed enterovirus 71 infection and acute neurologic manifestations. Magnetic resonance imaging (MRI) was performed in 4 patients with acute flaccid paralysis and 24 with rhombencephalitis.

RESULTS

The mean age of the patients was 2.5 years (range, 3 months to 8.2 years). Twenty-eight patients had hand-foot-and-mouth disease (68 percent), and 6 had herpangina (15 percent). The other seven patients had no skin or mucosal lesions. Three neurologic syndromes were identified: aseptic meningitis (in 3 patients); brain-stem encephalitis, or rhombencephalitis (in 37); and acute flaccid paralysis (in 4), which followed rhombencephalitis in 3 patients. In 20 patients with rhombencephalitis, the syndrome was characterized by myoclonic jerks and tremor, ataxia, or both (grade I disease). Ten patients had myoclonus and cranial-nerve involvement (grade II disease). In seven patients the brain-stem infection produced transient myoclonus followed by the rapid onset of respiratory distress, cyanosis, poor peripheral perfusion, shock, coma, loss of the doll's eye reflex, and apnea (grade III disease); five of these patients died within 12 hours after admission. In 17 of the 24 patients with rhombencephalitis who underwent MRI, T2-weighted scans showed high-intensity lesions in the brain stem, most commonly in the pontine tegmentum. At follow-up, two of the patients with acute flaccid paralysis had residual limb weakness, and five of the patients with rhombencephalitis had persistent neurologic deficits, including myoclonus (in one child), cranial-nerve deficits (in two), and ventilator-dependent apnea (in two).

CONCLUSIONS

In the 1998 enterovirus 71 epidemic in Taiwan, the chief neurologic complication was rhombencephalitis, which had a fatality rate of 14 percent. The most common initial symptoms were myoclonic jerks, and MRI usually showed evidence of brainstem involvement.

An epidemic of enterovirus 71 infection in Taiwan. Taiwan Enterovirus Epidemic Working Group

BACKGROUND

Enteroviruses can cause outbreaks of hand-foot-and-mouth disease (characterized by vesicular lesions on the hands, feet, and oral mucosa) or herpangina, usually without life-threatening manifestations. In 1998 an epidemic of enterovirus 71 infection caused hand-foot-and-mouth disease and herpangina in thousands of people in Taiwan, some of whom died.

METHODS

We assessed the epidemiologic aspects of this outbreak. Cases of hand-foot-and-mouth disease or herpangina in ambulatory patients were reported to the Taiwan Department of Health by a mean of 818 sentinel physicians. Severe cases in hospitalized patients were reported by 40 medical centers and regional hospitals. Viruses were isolated by 10 hospital laboratories and the department of health.

RESULTS

The sentinel physicians reported 129,106 cases of hand-foot-and-mouth disease or herpangina in two waves of the epidemic, which probably represents less than 10 percent of the estimated total number of cases. There were 405 patients with severe disease, most of whom were five years old or younger; severe disease was seen in all regions of the island. Complications included encephalitis, aseptic meningitis, pulmonary edema or hemorrhage, acute flaccid paralysis, and myocarditis. Seventy-eight patients died, 71 of whom (91 percent) were five years of age or younger. Of the patients who died, 65 (83 percent) had pulmonary edema or pulmonary hemorrhage. Among patients from whom a virus was isolated, enterovirus 71 was present in 48.7 percent of outpatients with uncomplicated hand-foot-and-mouth disease or herpangina, 75 percent of hospitalized patients who survived, and 92 percent of patients who died.

CONCLUSIONS

Although several enteroviruses were circulating in Taiwan during the 1998 epidemic, enterovirus 71 infection was associated with most of the serious clinical manifestations and with nearly all the deaths. Most of those who died were young, and the majority died of pulmonary edema and pulmonary hemorrhage.