RESUMEN
Echoviruses are among the most common worldwide causes of aseptic meningitis, which can cause long-term sequelae and death, particularly in neonates. However, the mechanisms by which these viruses induce meningeal inflammation are poorly understood, owing at least in part to the lack of in vivo models that recapitulate this aspect of echovirus pathogenesis. Here, we developed an in vivo neonatal mouse model that recapitulates key aspects of echovirus-induced meningitis. We show that expression of the human homologue of the primary echovirus receptor, the neonatal Fc receptor (FcRn), is not sufficient for infection of the brains of neonatal mice. However, ablation of type I, but not III, interferon (IFN) signaling in mice expressing human FcRn permitted high levels of echovirus replication in the brain, with corresponding clinical symptoms, including delayed motor skills and hind-limb weakness. Using this model, we defined the immunological response of the brain to echovirus infection and identified key cytokines, such as granulocyte colony-stimulating factor (G-CSF) and interleukin 6 (IL-6), that were induced by this infection. Lastly, we showed that echoviruses specifically replicate in the leptomeninges, where they induce profound inflammation and cell death. Together, this work establishes an in vivo model of aseptic meningitis associated with echovirus infections that delineates the differential roles of type I and type III IFNs in echovirus-associated neuronal disease and defines the specificity of echoviral infections within the meninges. IMPORTANCE Echoviruses are among the most common worldwide causes of aseptic meningitis, which can cause long-term sequelae or even death. The mechanisms by which echoviruses infect the brain are poorly understood, largely owing to the lack of robust in vivo models that recapitulate this aspect of echovirus pathogenesis. Here, we establish a neonatal mouse model of echovirus-induced aseptic meningitis and show that expression of the human homologue of the FcRn, the primary receptor for echoviruses, and ablation of type I IFN signaling are required to recapitulate echovirus-induced meningitis and clinical disease. These findings provide key insights into the host factors that control echovirus-induced meningitis and a model that could be used to test anti-echovirus therapeutics.
Asunto(s)
Infecciones del Sistema Nervioso Central , Infecciones por Echovirus , Meningitis Aséptica , Animales , Infecciones del Sistema Nervioso Central/fisiopatología , Infecciones del Sistema Nervioso Central/virología , Infecciones por Echovirus/complicaciones , Infecciones por Echovirus/fisiopatología , Infecciones por Echovirus/virología , Enterovirus Humano B/fisiología , Humanos , Inflamación , Interferón Tipo I/metabolismo , Interferones , Meningitis Aséptica/etiología , Meningitis Aséptica/fisiopatología , Meningitis Aséptica/virología , Ratones , Interferón lambdaRESUMEN
Inflammatory cardiomyopathy, characterized by inflammatory cell infiltration into the myocardium and a high risk of deteriorating cardiac function, has a heterogeneous aetiology. Inflammatory cardiomyopathy is predominantly mediated by viral infection, but can also be induced by bacterial, protozoal or fungal infections as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Despite extensive research, inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. At present, the reason why some patients recover without residual myocardial injury whereas others develop dilated cardiomyopathy is unclear. The relative roles of the pathogen, host genomics and environmental factors in disease progression and healing are still under discussion, including which viruses are active inducers and which are only bystanders. As a consequence, treatment strategies are not well established. In this Review, we summarize and evaluate the available evidence on the pathogenesis, diagnosis and treatment of myocarditis and inflammatory cardiomyopathy, with a special focus on virus-induced and virus-associated myocarditis. Furthermore, we identify knowledge gaps, appraise the available experimental models and propose future directions for the field. The current knowledge and open questions regarding the cardiovascular effects associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also discussed. This Review is the result of scientific cooperation of members of the Heart Failure Association of the ESC, the Heart Failure Society of America and the Japanese Heart Failure Society.
Asunto(s)
Cardiomiopatías/fisiopatología , Inflamación/fisiopatología , Miocarditis/fisiopatología , Virosis/fisiopatología , Animales , Antivirales/uso terapéutico , Autoinmunidad/inmunología , Biopsia , COVID-19/fisiopatología , COVID-19/terapia , Cardiomiopatías/diagnóstico , Cardiomiopatías/inmunología , Cardiomiopatías/terapia , Cardiomiopatía Dilatada , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/fisiopatología , Infecciones por Coronavirus/terapia , Infecciones por Coxsackievirus/inmunología , Infecciones por Coxsackievirus/fisiopatología , Infecciones por Coxsackievirus/terapia , Infecciones por Citomegalovirus/inmunología , Infecciones por Citomegalovirus/fisiopatología , Infecciones por Citomegalovirus/terapia , Modelos Animales de Enfermedad , Infecciones por Echovirus/inmunología , Infecciones por Echovirus/fisiopatología , Infecciones por Echovirus/terapia , Infecciones por Virus de Epstein-Barr/inmunología , Infecciones por Virus de Epstein-Barr/fisiopatología , Infecciones por Virus de Epstein-Barr/terapia , Eritema Infeccioso/inmunología , Eritema Infeccioso/fisiopatología , Eritema Infeccioso/terapia , Infecciones por VIH/fisiopatología , Hepatitis C/inmunología , Hepatitis C/fisiopatología , Hepatitis C/terapia , Humanos , Inmunoglobulinas Intravenosas/uso terapéutico , Factores Inmunológicos/uso terapéutico , Inflamación/diagnóstico , Inflamación/inmunología , Inflamación/terapia , Gripe Humana/inmunología , Gripe Humana/fisiopatología , Gripe Humana/terapia , Leucocitos/inmunología , Miocarditis/diagnóstico , Miocarditis/inmunología , Miocarditis/terapia , Miocardio/patología , Pronóstico , Infecciones por Roseolovirus/inmunología , Infecciones por Roseolovirus/fisiopatologíaRESUMEN
Echovirus 30 (E30), a member of the enterovirus B species, is a major cause of viral meningitis, targeting children and adults alike. While it is a frequently isolated enterovirus and the cause of several outbreaks all over the world, surprisingly little is known regarding its entry and replication strategy within cells. In this study, we used E30 strain Bastianni (E30B) generated from an infectious cDNA clone in order to study early entry events during infection in human RD cells. E30B required the newly discovered Fc echovirus receptor (FcRn) for successful infection, but not the coxsackievirus and adenovirus receptor (CAR) or decay-accelerating factor (DAF), although an interaction with DAF was observed. Double-stranded RNA replication intermediate was generated between 2 and 3 h postinfection (p.i.), and viral capsid production was initiated between 4 and 5 h p.i. The drugs affecting Rac1 (NSC 23766) and cholesterol (filipin III) compromised infection, whereas bafilomycin A1, dyngo, U-73122, wortmannin, and nocodazole did not, suggesting the virus follows an enterovirus-triggered macropinocytic pathway rather than the clathrin pathway. Colocalization with early endosomes and increased infection due to constitutively active Rab5 expression suggests some overlap and entry to classical early endosomes. Taken together, these results suggest that E30B induces an enterovirus entry pathway, leading to uncoating in early endosomes.IMPORTANCE Echovirus 30 (E30) is a prevalent enterovirus causing regular outbreaks in both children and adults in different parts of the world. It is therefore surprising that relatively little is known of its infectious entry pathway. We set out to generate a cDNA clone and gradient purified the virus in order to study the early entry events in human cells. We have recently studied other enterovirus B group viruses, like echovirus 1 (EV1) and coxsackievirus A9 (CVA9), and found many similarities between those viruses, allowing us to define a so-called "enterovirus entry pathway." Here, E30 is reminiscent of these viruses, for example, by not relying on acidification for infectious entry. However, despite not using the clathrin entry pathway, E30 accumulates in classical early endosomes.
Asunto(s)
Infecciones por Echovirus/fisiopatología , Enterovirus Humano B/genética , Enterovirus Humano B/metabolismo , Células A549 , Animales , Células CHO , Línea Celular , Cricetulus , Brotes de Enfermedades , Infecciones por Echovirus/virología , Enterovirus/genética , Enterovirus Humano B/patogenicidad , Infecciones por Enterovirus/virología , Humanos , Filogenia , ARN Viral/genética , Receptores Fc/genética , Análisis de Secuencia de ADN/métodos , Internalización del Virus , Replicación ViralRESUMEN
BACKGROUND: Echovirus 30 (E30) is one of the most common causative agents for aseptic meningitis. OBJECTIVES: In the autumn of 2017, there was an outbreak caused by E30 in Kushiro, Hokkaido, Japan. The aim of this study was to characterize this outbreak. STUDY DESIGN: Fifty-nine patients were admitted to the Department of Pediatrics, Kushiro Red Cross Hospital (KRCH) with clinical diagnosis of aseptic meningitis. Among those, 36 patients were finally diagnosed as E30-associated aseptic meningitis by the detection of viral RNA using reverse transcription-polymerase chain reaction (RT-PCR) and/or the evidence of more than four-fold rise in neutralizing antibody (NA) titers in the convalescent phase relative to those in the acute phase. We investigated these 36 confirmed cases. RESULTS: The median age was 6 years (range: 6 months-14 years). The positive signs and symptoms were as follows: fever (100%), headache (94%), vomiting (92%), jolt accentuation (77%), neck stiffness (74%), Kernig sign (29%), and abdominal pain (28%). The median cerebrospinal fluid (CSF) white cell count, neutrophil count, and lymphocyte count were 222/µL (range: 3-1434/µL), 144/µL (range: 1-1269/µL), and 85/µL (range: 2-354/µL), respectively. Although the detected viral genes demonstrated same cluster, they were different from E30 strains observed in Japan between 2010 and 2014. CONCLUSION: We mainly showed clinical and virological features of the E30-associated aseptic meningitis outbreak that occurred in Kushiro. To prevent further spread of E30 infection, continuous surveillance of enterovirus (EV) circulation and standard precautions are considered essential.
Asunto(s)
Brotes de Enfermedades , Infecciones por Echovirus/epidemiología , Infecciones por Echovirus/virología , Enterovirus Humano B/aislamiento & purificación , Meningitis Aséptica/epidemiología , Meningitis Aséptica/virología , Adolescente , Anticuerpos Neutralizantes/sangre , Líquido Cefalorraquídeo/citología , Niño , Preescolar , Infecciones por Echovirus/patología , Infecciones por Echovirus/fisiopatología , Enterovirus Humano B/clasificación , Enterovirus Humano B/genética , Enterovirus Humano B/inmunología , Femenino , Genotipo , Hospitales Pediátricos , Humanos , Lactante , Japón/epidemiología , Masculino , Meningitis Aséptica/patología , Meningitis Aséptica/fisiopatología , Filogenia , ARN Viral/genética , Proteínas Virales/genéticaAsunto(s)
Infecciones por Echovirus/fisiopatología , Infecciones por Enterovirus/fisiopatología , Fiebre Aftosa/virología , Índice de Severidad de la Enfermedad , Adolescente , Adulto , Anciano , Animales , Niño , Preescolar , Enterovirus/inmunología , Enterovirus/patogenicidad , Enterovirus Humano B/inmunología , Enterovirus Humano B/patogenicidad , Infecciones por Enterovirus/líquido cefalorraquídeo , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Serogrupo , Reino Unido , Adulto JovenRESUMEN
BACKGROUND: Enteroviruses (EVs) are considered as a major viral etiological cause of aseptic meningitis in children. OBJECTIVES: We assessed the clinical and virological features of an aseptic meningitis outbreak in North-East of France, 2005. STUDY DESIGN: Classical bacteriological analysis, Herpesviridae and EV PCR assays had been prospectively performed on cerebrospinal fluid (CSF) samples taken from 80 children hospitalized for aseptic meningitis. For each EV strain identified as etiological agent, a phylogenetic comparison of partial EV VP1 capsid protein coding gene was performed. RESULTS: The children older than 12 months (n=75) presented a typical aseptic meningitis syndrome, whereas the children aged less than 1 year (n=5) demonstrated only fever and hypotonia. Among the 80 studied children, EV was identified as the etiological cause of aseptic meningitis in 73 (91%) cases. Echovirus 30 (E30) was the most common isolated serotype (84% of 51 EV strains). VP1 phylogenetic analysis revealed that E30 strains were genetically closer to those isolated during 2000 aseptic meningitis outbreak comparatively to those identified during 2003 and 2006 non-epidemic years. Moreover, the genetic study demonstrated the co-circulation of four distinct lineages without any difference in temporal distribution or clinical features during the 2005 outbreak. CONCLUSIONS: The present report demonstrates the co-circulation of distinct E30 lineages during the same aseptic meningitis outbreak season. This E30 genetic diversity may be a prerequisite for the emergence of new strains potentially responsible for further aseptic meningitis outbreaks.
Asunto(s)
Brotes de Enfermedades , Infecciones por Echovirus , Enterovirus Humano B , Meningitis Aséptica , Meningitis Viral , Adolescente , Proteínas de la Cápside/genética , Niño , Preescolar , Infecciones por Echovirus/epidemiología , Infecciones por Echovirus/fisiopatología , Infecciones por Echovirus/virología , Enterovirus Humano B/clasificación , Enterovirus Humano B/genética , Enterovirus Humano B/aislamiento & purificación , Francia/epidemiología , Humanos , Lactante , Meningitis Aséptica/epidemiología , Meningitis Aséptica/fisiopatología , Meningitis Aséptica/virología , Meningitis Viral/epidemiología , Meningitis Viral/fisiopatología , Meningitis Viral/virología , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADNRESUMEN
Taiwan has experienced several outbreaks of enterovirus 71 (EV71) infections since 1998. This study examined the quantitative relationship between specific cytokines in the cerebrospinal fluid (CSF) and the severity of EV71 brain stem encephalitis (BE), and investigated whether the CSF cytokine response differed from that to uncomplicated echovirus meningitis (EM). The study included 57 children with EV71 BE, of whom 24 had isolated BE, 24 had autonomic nervous system (ANS) dysregulation, and nine had pulmonary oedema (PE), and 15 children with EM. All were confirmed by virus culture. Mean CSF glucose, total protein and lactate levels were increased significantly in association with the severity of EV71 BE. The mean CSF concentration of interleukin (IL)-1beta in children with EV71 PE was significantly higher than in those with isolated BE. IL-6 and interferon (IFN)-gamma levels were significantly higher for EV71 PE and ANS dysregulation than for isolated BE. In contrast, EM was associated with high levels of IL-1beta and low levels of IFN-gamma. Cytokines in the central nervous system, as well as in blood, appear to be involved in the pathogenesis of EV71 BE.
Asunto(s)
Tronco Encefálico/fisiopatología , Citocinas/líquido cefalorraquídeo , Encefalitis Viral/fisiopatología , Infecciones por Enterovirus/inmunología , Enterovirus/patogenicidad , Tronco Encefálico/inmunología , Tronco Encefálico/virología , Preescolar , Brotes de Enfermedades , Infecciones por Echovirus/epidemiología , Infecciones por Echovirus/inmunología , Infecciones por Echovirus/fisiopatología , Infecciones por Echovirus/virología , Encefalitis Viral/epidemiología , Encefalitis Viral/inmunología , Encefalitis Viral/virología , Enterovirus/inmunología , Enterovirus Humano B/inmunología , Enterovirus Humano B/patogenicidad , Infecciones por Enterovirus/epidemiología , Infecciones por Enterovirus/fisiopatología , Infecciones por Enterovirus/virología , Femenino , Humanos , Lactante , Masculino , Meningitis Viral/epidemiología , Meningitis Viral/inmunología , Meningitis Viral/fisiopatología , Meningitis Viral/virología , Índice de Severidad de la Enfermedad , Taiwán/epidemiologíaRESUMEN
Nonpolio enterovirus (NPEV) infections are known to cause a wide range of illnesses in the neonatal period. In most cases, NPEV is presumed to be contracted during birth. Intrauterine NPEV infections occur infrequently. A case of intrauterine echovirus 11 infection with pneumonia, persistent pulmonary hypertension of the newborn, and purpura fulminans is presented.
Asunto(s)
Infecciones por Echovirus/complicaciones , Enterovirus Humano B , Enfermedades Fetales/virología , Hipertensión Pulmonar/virología , Neumonía Viral/virología , Infecciones por Echovirus/fisiopatología , Infecciones por Echovirus/terapia , Resultado Fatal , Femenino , Humanos , Hipertensión Pulmonar/fisiopatología , Hipertensión Pulmonar/terapia , Vasculitis por IgA/virología , Recién Nacido , Embarazo , Complicaciones Infecciosas del Embarazo/fisiopatologíaRESUMEN
From May to August 1998 an epidemic of aseptic meningitis (AM) due to echovirus type 30 (E30) occurred in Yamaguchi prefecture, Japan. We performed single-photon emission-computed tomography (SPECT) to evaluate cerebral perfusion during the acute stage in 27 patients with AM due to E30. Moreover, we measured the cerebrospinal fluid (CSF) concentrations of soluble tumor necrosis factor receptor (sTNF-R) and interleukin-1 beta (IL-1beta) in all 27 patients, and the serum concentration of soluble E-selectin (sE-selectin) in 19 of the 27 patients, which is responsible for vasculitis, by means of a sandwich enzyme-linked immunosorbent assay. In 20 of the 27 (74.1%) children, SPECT imaging revealed localized cerebral hypoperfusion without abnormal focal neurological findings or symptoms. Follow-up SPECT after about 1 month revealed no abnormalities. The CSF concentrations of sTNF-R and IL-1beta, and the serum concentration of sE-selectin in the group with abnormal findings on SPECT were significantly higher than those in the group without abnormal findings on SPECT and the control subjects. Our results indicate that transient reduced regional blood flow is a frequent finding in children with AM due to E30 infection and that this abnormal finding may be induced by cerebral vasculitis.
Asunto(s)
Ganglios Basales/virología , Corteza Cerebral/virología , Circulación Cerebrovascular/fisiología , Infecciones por Echovirus/complicaciones , Enterovirus Humano B/fisiología , Meningitis Viral/complicaciones , Ganglios Basales/irrigación sanguínea , Ganglios Basales/fisiopatología , Corteza Cerebral/irrigación sanguínea , Corteza Cerebral/fisiopatología , Niño , Preescolar , Selectina E/sangre , Infecciones por Echovirus/patología , Infecciones por Echovirus/fisiopatología , Femenino , Humanos , Lactante , Interleucina-1/líquido cefalorraquídeo , Masculino , Meningitis Viral/patología , Meningitis Viral/fisiopatología , Receptores del Factor de Necrosis Tumoral/metabolismo , Tomografía Computarizada de Emisión de Fotón ÚnicoAsunto(s)
Enterovirus Humano B , Regiones no Traducidas 5' , Animales , Membrana Celular/metabolismo , Infecciones por Echovirus/epidemiología , Infecciones por Echovirus/fisiopatología , Enterovirus Humano B/clasificación , Enterovirus Humano B/genética , Enterovirus Humano B/aislamiento & purificación , Humanos , Conformación de Ácido Nucleico , Picornaviridae/genética , Procesamiento Proteico-Postraduccional , Proteínas Virales/análisisRESUMEN
Clinical manifestations of neonatal echovirus type 18 infections include a nonspecific febrile illness, diarrhea, and meningitis with or without exanthem. We report a successful outcome in a case of neonatal sepsis with shock caused by echovirus type 18, a complication not previously associated with this serotype.
Asunto(s)
Infecciones por Echovirus/congénito , Enterovirus Humano B , Sepsis/congénito , Adulto , Infecciones por Echovirus/fisiopatología , Femenino , Humanos , Recién Nacido , Embarazo , Sepsis/fisiopatología , Sepsis/virologíaRESUMEN
An outbreak of aseptic meningitis caused by echovirus type 9 occurred between March and October, 1990, in Kagoshima, Southern Japan. Clinical manifestations and laboratory data of 259 children with aseptic meningitis who were admitted to the outpatient clinic of pediatrics in the Kagoshima City Hospital were analyzed (other diseases caused by echovirus type 9 were not investigated). The patients' age ranged from 1 month to 15 years and the highest incidence was in 4-year-old children. The male:female ratio was 1.3:1. Frequencies of headache (69%), vomiting (64%), neck stiffness (36%) and rash (195%) were lower than those in the previous reports in the United States or in the Europe. Pleocytosis in the cerebrospinal fluid increased with increasing age in the younger children. A predominance of neutrophils in cerebrospinal fluid lasted for 3 days or more after onset in 16% of the patients. Seroepidemiologic study suggested that the accumulation of susceptible children < 5 years of age had predisposed to the epidemic.
Asunto(s)
Brotes de Enfermedades , Echovirus 9/aislamiento & purificación , Infecciones por Echovirus/epidemiología , Meningitis Aséptica/epidemiología , Adolescente , Distribución por Edad , Atención Ambulatoria , Niño , Preescolar , Infecciones por Echovirus/líquido cefalorraquídeo , Infecciones por Echovirus/diagnóstico , Infecciones por Echovirus/fisiopatología , Femenino , Humanos , Incidencia , Lactante , Japón/epidemiología , Masculino , Meningitis Aséptica/líquido cefalorraquídeo , Meningitis Aséptica/diagnóstico , Meningitis Aséptica/fisiopatología , Pronóstico , Factores de Riesgo , Estudios Seroepidemiológicos , Distribución por SexoRESUMEN
Analysis of clinical manifestations of a total enteroviral infection with ECHO-11 virus-induced uveitis in 58 infants aged 2 weeks to 1.5 years has shown that uveitis develops on days 1-10 of the disease and is associated with a weak injection, endothelial edema, hyperemia and edema of the iris rapidly eventuating in destruction of the pigment lamina and fenestration. Posterior synechiae, pupil deformations, grave uveitis with hypotonia of 4-10 mm Hg are rapidly developing. A two-year follow-up has shown marked hemo- and hydrodynamic disorders, retarded growth of the involved eye, development of grave complications in 60 percent of patients. The most characteristic late complications were iridal fenestration, pseudocoloboma-type pupil deformation, formation of prelental films, often pigmented. The condition is associated with active production of virus-neutralizing antibodies in titers of 1:4 to 1:16384. No relationship between the clinical course and antibody titers was revealed.
Asunto(s)
Infecciones por Echovirus/fisiopatología , Infecciones Virales del Ojo/fisiopatología , Uveítis/microbiología , Formación de Anticuerpos , Femenino , Hemodinámica/fisiología , Humanos , Lactante , Recién Nacido , Masculino , Uveítis/fisiopatologíaRESUMEN
An epidemic disease with maculopapular exanthem, especially on the face and the extremities was observed form June to July of 1988 in Kitakyushu-shi. The clinical findings of 15 patients (male 12, female 3) with exanthem were described. Symptoms included fever (10 patients), diarrhea (5), cough and nasal discharge (2), headache and vomiting (1), and hyperreflexia (1). Echovirus type 18 was isolated from throat swabs and stool samples of 9 patients.
Asunto(s)
Infecciones por Echovirus , Preescolar , Diarrea Infantil/etiología , Infecciones por Echovirus/epidemiología , Infecciones por Echovirus/microbiología , Infecciones por Echovirus/fisiopatología , Exantema/etiología , Femenino , Fiebre/etiología , Humanos , Lactante , Japón/epidemiología , MasculinoRESUMEN
An epidemic of diarrhoea with two distinct waves affected a village of 1375 people in southern India in 1983. The first wave of the epidemic, from the last week of December 1982, had a sharp peak in January 1983 and was over by March. Echovirus type 11 was isolated from patients, who also had a serum antibody response to the virus. During the second wave of the epidemic, from May to September 1983, the clinical features were different and Shigella flexneri was isolated without significant viral isolates. Infection during the first wave did not protect from the second wave. Virus isolation was in human intestinal tumour-derived differentiated epithelial cell lines; such cell lines may be useful for the isolation and identification of enteroviruses in clinical samples.
Asunto(s)
Diarrea/microbiología , Brotes de Enfermedades/microbiología , Infecciones por Echovirus/microbiología , Diarrea/fisiopatología , Infecciones por Echovirus/fisiopatología , Heces/microbiología , Humanos , India , Factores de TiempoRESUMEN
14 subjects with influenza or echovirus infection, all suffering myalgia, and 9 subjects with mumps, in whom this symptom was lacking, were investigated with single fibre electromyography (EMG) in the acute phase and during convalescence to reveal a possible disturbance in neuromuscular transmission. In both groups about the same percentage of the potential pairs studied showed abnormal transmission characteristics in the acute phase. Two weeks after the acute infection, this percentage had decreased significantly in the group with myalgia, whilst in the non-myalgia group it was still at the same level. However, on both occasions of investigation and in both groups the percentages were substantially greater than those recorded in healthy individuals. This study demonstrates that acute febrile infections may adversely affect neuromuscular transmission in previously healthy human subjects. The effects observed might offer an explanation to the accentuated muscular weakness in association with infections in patients with an already low safety margion of neuromuscular transmission, e.g. in myasthenia gravis.