Influenza, Campylobacter and Mycoplasma infections, and hospital admissions for Guillain-Barré syndrome, England

Defining the balance between optimal immunity and immunopathology in influenza virus infection

Influenza A viruses remain a global threat to human health, with continued pandemic potential. In this Review, we discuss our current understanding of the optimal immune responses that drive recovery from influenza virus infection, highlighting the fine balance between protective immune mechanisms and detrimental immunopathology. We describe the contribution of innate and adaptive immune cells, inflammatory modulators and antibodies to influenza virus-specific immunity, inflammation and immunopathology. We highlight recent human influenza virus challenge studies that advance our understanding of susceptibility to influenza and determinants of symptomatic disease. We also describe studies of influenza virus-specific immunity in high-risk groups following infection and vaccination that inform the design of future vaccines to promote optimal antiviral immunity, particularly in vulnerable populations. Finally, we draw on lessons from the COVID-19 pandemic to refocus our attention to the ever-changing, highly mutable influenza A virus, predicted to cause future global pandemics.

Neurological features related to influenza virus in the pediatric population: a 3-year monocentric retrospective study

Influenza virus is generally characterized by fever, myalgia, and respiratory symptoms. Neurological entities have already been described, such as acute necrotizing encephalitis (ANE). We aimed to highlight the non-exceptional nature and explore the clinical spectrum and evolution of neurological features related to influenza virus in children. This monocentric observational study included patients under 18 years old, positive for influenza virus, between January 2017 and April 2019 in a pediatric university hospital. Patients were classified into two groups: those with or without a previous significant neurological or metabolic disorder. Two hundred eighty-nine children were identified with influenza infection. Thirty seven had a neurological manifestation: 14 patients who had previous significant neurological or metabolic disorder and 23 patients with no medical history. We identified several clinical patterns: 22 patients had seizures, 7 behavior disorders, 5 disturbances of consciousness, and 3 motor deficits. Four were diagnosed with a known influenza-associated neurological syndrome: 1 ANE, 1 cytotoxic lesion of the corpus callosum, 1 hemiconvulsion-hemiplegia-epilepsia syndrome, and 1 recurrent encephalitis in the context of a RANBP2 mutation. The neurological outcome was favorable in most cases. None of the patients with previous significant disorder retained sequalae or had a recurrence. Two patients had a fatal outcome, and both had a predisposing disorder.

CONCLUSION

Various neurological manifestations can be associated with influenza virus. Certain entities led to a poor prognosis, but in most cases, symptoms improved within a few days. The severity of the neurological manifestations correlated with previous neurological or metabolic disorders.

WHAT IS KNOWN

• Influenza viruses are well known pathogens with a seasonal epidemic evolution, particularly affecting children. These viruses cause acute fever with respiratory symptoms, associated with myalgia and headaches. Neurological presentation in influenza-virus infection is a well-established possibility as influenza virus is considered to be responsible for 27 to 36% of childhood encephalitis. Some specific and severe entity as acute necrotizing encephalitis, cytotoxic lesion of the corpus callosum, or Hemiconvulsion-hemiplegia-epilepsy syndrome are well described.

WHAT IS NEW

• In a French monocentric cohort of 37 children with influenza-related neurologic manifestations, the majority of these manifestations, including seizure, drowsiness, motor deficiency, hallucination… are self limiting and do not lead to after-effects. In rare cases (4/37), they may reveal severe encephalitis requiring rapid and appropriate treatment. Otherwise, comparison of a group of 14 children with underlying neurological or metabolic disorder with a group of 23 children free of any significant disorder show that the severity of the neurological manifestations was largely related to previous neurological or metabolic disorders highlighting the importance of vaccination in this population.

Postpartum Guillain-Barré syndrome: a case report

Guillain-Barré syndrome (GBS) is an immune-mediated disorder of the central nervous system presenting as symmetrical, progressive weakness and areflexia. The incidence of GBS is very low during pregnancy, but the risk increases in the postpartum period. The management is done by intravenous immunoglobulin or conservatively.

Case Presentation

Case of 27 years female with parity 1, living 1, on postpartum day 20 presented to the emergency department (ED) with weakness over legs and hands since 20 days following emergency lower segment cesarean section for her delivery. The weakness prevailed over the lower extremities and progressed to the upper extremities in 4-5 days, affecting her grip strength and ability to stand alone. No history of prior diarrheal or respiratory illness. Cerebrospinal fluid analysis revealed albuminocytologic dissociation. A nerve conduction study showed in-excitable bilateral radial, median, ulnar, and sural nerves. Intravenous immunoglobulin was administered at the rate of 0.4 g/kg once daily for 5 days. Patient was discharged after 2 weeks with regular physiotherapy follow-up.

Conclusion

GBS in the postpartum period is very rare. There must be a high degree of suspicion among physicians for GBS if a pregnant female or a woman during her postpartum period presents with ascending muscle paralysis, even if there is no recent antecedent history of diarrheal episodes or respiratory illness. An early diagnosis with multidisciplinary supportive measures helps improve the prognosis for both the mother and the fetus.

Acute/chronic inflammatory polyradiculoneuropathy

Autoimmune neuropathy may present acutely or with a more progressive and/or relapsing and remitting course. Acute inflammatory neuropathy or Guillain-Barré syndrome (GBS) has variable presentations but by far the most common is acute inflammatory demyelinating polyradiculoneuropathy which is characterized by rapidly progressive proximal and distal symmetric weakness, sensory loss, and depressed reflexes. The most common chronic autoimmune neuropathy is chronic inflammatory demyelinating polyradiculoneuropathy, which in its most typical form is clinically similar to acute inflammatory demyelinating polyradiculoneuropathy (proximal and distal symmetric weakness, sensory loss, and depressed reflexes) but differs in that onset is much more gradual, i.e., over at least 8 weeks. While the majority of GBS cases result from a postinfectious activation of the immune system, presumably in a genetically susceptible host, less is understood regarding the etiopathogenesis of chronic inflammatory demyelinating polyradiculoneuropathy. Both acute and chronic forms of these inflammatory neuropathies are driven by some combination of innate and adaptive immune pathways, with differing contributions depending on the neuropathy subtype. Both disorders are largely clinical diagnoses, but diagnostic tools are available to confirm the diagnosis, prognosticate, detect variant forms, and rule out mimics. Given the autoimmune underpinnings of both disorders, immunosuppressive and immunomodulating treatments are typically given in both diseases; however, they differ in their response to treatment.

Characteristics of Guillain-Barre Syndrome Patient Underwent Hyperbaric Oxygen Therapy at Lakesla 2016–2019

BACKGROUND: Guillain-Barre syndrome (GBS) is considered an acute immune-mediated monophasic illness. Standard therapy includes intravenous immunoglobulin (IVIG) and/or plasmapheresis. Yet, long-standing disability remains a problem. In Indonesia, the availability and cost of these therapies are constraints. AIM: To show the capability of hyperbaric oxygen (HBO2) therapy in GBS patients who did not undergo standard therapy. HBO2 also provides healing in patients who experience delays in therapy. METHODS: Data included identity, demographic, social history, current disease history, disease progression and therapies used. Data were displayed in the form of tables and graphs. RESULTS: Twenty-five GBS patients underwent HBO2 from 2016 to 2019. The majority of patients were males aged 20-30 years, triggered by preceding diarrhea. After approximately three to ten days following HBO2, they felt their first positive changes. They walked with assistance after two to three weeks receiving HBO2 and without assistance after four to 12 weeks receiving HBO2. CONCLUSION: HBO2 administration show clinical improvement in GBS patients. HBO2 is expected to become an adjuctive therapy for GBS patients in Indonesia.

Antecedent infections and vaccinations in chronic inflammatory demyelinating polyneuropathy: A European collaborative study

INTRODUCTION/AIMS

Chronic inflammatory demyelinating polyneuropathy (CIDP) may be rarely preceded by infection. A causative link remains unproven, in contrast to Guillain-Barré syndrome (GBS), which is commonly postinfectious with well-demonstrated pathophysiological mechanisms of molecular mimicry following Campylobacter jejuni enteritis. Uncommonly, infections are reported before the onset of CIDP. In this study we aimed to determine the frequency and characteristics of CIDP occurring after antecedent infections or vaccinations in two large European cohorts.

METHODS

We reviewed the records of 268 subjects with "definite" or "probable" CIDP from the Inflammatory Neuropathy Clinic, Birmingham, UK (129 subjects), and from the Serbian national CIDP database (139 subjects).

RESULTS

Twenty-five of 268 (9.3%) subjects had a respiratory or gastrointestinal infection in the 6 weeks preceding CIDP onset, and 3 of 268 (1.1%) had received an influenza vaccination. CIDP disease onset occurred at a younger age (mean [standard deviation], 44.25 [17.36] years vs 54.05 [15.19] years; P < .005) and acute-onset CIDP was more common (42.9% vs 12.1%; odds ratio, 5.46; 95% confidence interval, 2.35-12.68; P < .001) in subjects with preceding infections or vaccinations. No differences in CIDP subtype, rates of cerebrospinal fluid protein level elevation, disability, or likelihood of treatment response, were observed.

DISCUSSION

Antecedent infections or vaccinations may precede about 10% of cases of CIDP and are more common in younger subjects. Acute-onset CIDP is more frequent after antecedent events. These findings may suggest specific pathophysiological mechanisms in such cases.

Incidence of Guillain-Barré Syndrome is not Associated with Influenza Vaccination in the Elderly

We aimed to analyze the incidence of Guillain-Barré syndrome (GBS) and its association with influenza vaccination (IV) in the elderly population. This study included 2470 patients hospitalized with GBS (G61.0) between 2014 and 2016 based on the Korean National Health Insurance Service (NHIS) claims data. We reviewed every medical claim in the 42 days preceding GBS diagnosis looking for precedent causes of GBS. To assess the relationship between IV and the development of GBS, data from the NHIS and the National Vaccination Registry were combined and analyzed. Using a self-controlled case series (SCCS) approach, we calculated the incidence rate ratio by setting the risk period as 42 days following vaccination. The annual background incidence of GBS was estimated at 4.15 per 100,000 persons. More than half of the patients with newly developed GBS had a previous infection or surgery. The incidence of GBS within 42 days of IV was estimated at 0.32 per 100,000 vaccinated persons. SCCS analysis showed that the risk of GBS was not significantly higher. While GBS can potentially develop from various infections, no association was found between GBS and IV. These results will contribute to developing an evidence-based vaccine policy that includes a clear causality assessment of adverse events.

Neurologic Manifestations of Severe Respiratory Viral Contagions

Endemic and pandemic viral respiratory infections have recently emerged as a critical topic of investigation given the recent severe acute respiratory syndrome coronavirus-2 outbreak. Data from such outbreaks indicate that severe systemic comorbidities including acute neurologic illness are associated with illness and lead to significant outcome differences. Herein, we will discuss the neurologic manifestations of severe viral respiratory infections including coronavirus, influenza, respiratory syncytial virus, metapneumovirus, and enterovirus.

Data Sources

PubMed and EMBASE were searched by two independent investigators up to March 2020.

Study Selection

Data selection included preclinical and clinical studies detailing neurologic manifestations of viral respiratory infections.

Data Extraction and Synthesis

Two independent investigators reviewed and extracted the data.

Conclusions

Neurologic manifestations including seizures, status epilepticus, encephalitis, critical illness neuromyopathy, acute disseminated encephalomyelitis, acute necrotizing encephalitis, Guillan-Barré syndrome, transverse myelitis, and acute flaccid myelitis have all been associated with severe viral respiratory infections. Having an understanding of the direct neurotropism of such viruses is imperative to understanding pathogenesis, clinical presentation, and potential treatment paradigms aimed at improving morbidity and mortality.

Is an Increased Risk of Developing Guillain-Barré Syndrome Associated with Seasonal Influenza Vaccination? A Systematic Review and Meta-Analysis

While the weight of epidemiological evidence does not support a causal link with influenza vaccination evaluated over the last 30 years, Guillain–Barré syndrome (GBS) has been considered a vaccine-associated adverse event of interest since 1976. To investigate the existence of GBS risk after vaccination against seasonal influenza, a systematic review and meta-analysis have been conducted based on 22 eligible epidemiological studies from 1981 to 2019 reporting 26 effect sizes (ESs) in different influenza seasons. The primary result of our meta-analysis pointed to no risk of vaccine-associated GBS, as documented by a pooled ES of 1.15 (95% CI: 0.97–1.35). Conversely, an obvious high risk of GBS was observed in patients with previous influenza-like illness (ILI), as demonstrated by a pooled ES of 9.6 (95% CI: 4.0–23.0) resulting from a supplementary analysis. While the meta-analysis did not confirm the putative risk of vaccine-associated GBS suggested by many epidemiological studies, vaccination against seasonal influenza reduced the risk of developing ILI-associated GBS by about 88%. However, to obtain strong evidence, more epidemiological studies are warranted to establish a possible coincidence between vaccination and ILI prior to GBS onset.

Incidence of Travelers' Diarrhea among Adult Foreign Travelers in Thailand: A Prospective Study

Travelers' diarrhea (TD) is common among foreign travelers to Thailand. We performed a prospective cohort study to determine the TD incidence among foreign adult travelers to Thailand. We retrieved baseline demographic data, travel plans, and health history on enrolling individuals and collected follow-up questionnaires on days 7, 14, and 28 from the day of arrival. We analyzed data from 349 eligible participants. The mean participants' age was 32.3 years; 55.4% were men. Most of the participants had visited a travel clinic for vaccinations and counseling after arrival in Thailand. The cumulative incidences of the participants developing TD were 14.0% (49/349), 23.5% (82/349), and 33.0% (115/349) at 7, 14, and 28 days, respectively. The median time to develop TD was 9 days (interquartile range 5-18 days) post-arrival. Of 115 participants with TD, 64.3% (74/115) consulted a physician, 1.7% (2/115) were hospitalized, and 11.3% (13/115) had to change their travel plans. We identified young age, eating street food, and not routinely washing hands after using a toilet as risk factors significantly associated with the incidence of TD using the log-rank test in our survival analysis. Up to one-third of foreign travelers developed diarrhea during the first month, and some cases were severe. Although no highly effective TD prevention method exists, the practice of good personal hygiene and avoidance of food and drinks derived from unsanitary sources are still recommended to reduce the risk of travelers' TD.

Vaccines and the risk of Guillain-Barré syndrome

The role of vaccination in the development of Guillain-Barré syndrome (GBS) is controversial, although cases of GBS have been reported following a wide range of vaccines. A nested case-control study was conducted between January 2011 and December 2015 in three Chinese cities. Four controls were matched to a case by gender, age, address and index date. An independent expert committee validated the diagnoses of cases and controls according to the Brighton Collaboration GBS case definition. Data on vaccinations were obtained from computerized vaccination records. Causal relations were assessed by conditional logistic regression. 1056 cases of GBS and 4312 controls were included in the analyses. Among paediatric and adult population, adjusted ORs for GBS occurrence within 180 days following vaccination were 0.94 (95% CI 0.54-1.62) and 1.09 (95% CI 0.88-1.32), respectively. No increased risk of GBS was detected for vaccination against hepatitis B, influenza, hepatitis A, varicella, rabies, polio(live), diphtheria, pertuss(acellular), tetanusis, measles, mumps, rubella, Japanese Encephalitis, and meningitis vaccines. Adjusted ORs for the recurrence of GBS after vaccination among paediatric and adult population were 0.85 (95% CI 0.07-9.50) and 1.18 (95% CI 0.49-2.65), respectively. In this large retrospective study, we did not find evidence of an increased risk of GBS and its recurrence among either paediatric (≤ 18 years) or adult (> 18 years) individuals within the 180 days following vaccinations of any kind, including influenza vaccination.

Guillain-Barré syndrome and influenza vaccines: current evidence

OBJECTIVE

Guillain-Barré Syndrome (GBS) as a consequence of influenza vaccination is a relevant topic, yet to be clarified, which raises concern both amongst health care personnel and the general population. Every study and pharmacovigilance system point to need of further research and the importance of continuous monitoring of safety regarding influenza vaccines. The aim of the present study is to investigate the publication of new data since the realisation of our meta-analysis of GBS and influenza vaccines (published in 2015).

METHODS

A systematic revision of PubMed, Embase, and Web of Knowledge (WOS) databases has been carried out. These report observational studies assessing GBS risk after the administration of influenza vaccines from May 2014 up to July 20th, 2017.

RESULTS

The research yielded 107 articles. Only three studies met established inclusion criteria and referred to an estimation GBS risk after some influenza vaccine. Two studies investigated GBS risk by the pandemic A/H1N1 vaccine, while only one looked into season vaccines.

CONCLUSIONS

The present systematic review, conducted after the publication of our previous meta-analysis, seems to confirm its previous results. Therefore, GBS should be considered an infrequent adverse effect of influenza vaccination, which should not negatively influence its acceptance. Unfortunately, very few of the systematically surveyed studies meeting inclusion criteria. This fact sharply contrasts with the current consensus as to the need of continuously monitoring the safety of influenza vaccines.

The hidden burden of influenza: A review of the extra-pulmonary complications of influenza infection

Severe influenza infection represents a leading cause of global morbidity and mortality. Although influenza is primarily considered a viral infection that results in pathology limited to the respiratory system, clinical reports suggest that influenza infection is frequently associated with a number of clinical syndromes that involve organ systems outside the respiratory tract. A comprehensive MEDLINE literature review of articles pertaining to extra‐pulmonary complications of influenza infection, using organ‐specific search terms, yielded 218 articles including case reports, epidemiologic investigations, and autopsy studies that were reviewed to determine the clinical involvement of other organs. The most frequently described clinical entities were viral myocarditis and viral encephalitis. Recognition of these extra‐pulmonary complications is critical to determining the true burden of influenza infection and initiating organ‐specific supportive care.

Simulation study of the effect of influenza and influenza vaccination on risk of acquiring Guillain-Barré syndrome

Under typical conditions, such as influenza incidence rates of >5% and vaccine effectiveness >60%, vaccination reduced risk.

It is unclear whether seasonal influenza vaccination results in a net increase or decrease in the risk for Guillain-Barré syndrome (GBS). To assess the effect of seasonal influenza vaccination on the absolute risk of acquiring GBS, we used simulation models and published estimates of age- and sex-specific risks for GBS, influenza incidence, and vaccine effectiveness. For a hypothetical 45-year-old woman and 75-year-old man, excess GBS risk for influenza vaccination versus no vaccination was −0.36/1 million vaccinations (95% credible interval −1.22 to 0.28) and −0.42/1 million vaccinations (95% credible interval, –3.68 to 2.44), respectively. These numbers represent a small absolute reduction in GBS risk with vaccination. Under typical conditions (e.g. influenza incidence rates >5% and vaccine effectiveness >60%), vaccination reduced GBS risk. These findings should strengthen confidence in the safety of influenza vaccine and allow health professionals to better put GBS risk in context when discussing influenza vaccination with patients.

Relationship between Guillain-Barré syndrome, influenza-related hospitalizations, and influenza vaccine coverage

Some studies reported an increased risk of Guillain-Barré syndrome (GBS) within six weeks of influenza vaccination. It has also been suggested that this finding could have been confounded by influenza illnesses. We explored the complex relationship between influenza illness, influenza vaccination, and GBS, from an ecologic perspective using nationally representative data. We also studied seasonal patterns for GBS hospitalizations. Monthly hospitalization data (2000-2009) for GBS, and pneumonia and influenza (P&I) in the Nationwide Inpatient Sample were included. Seasonal influenza vaccination coverage for 2004-2005 through the 2008-2009 influenza seasons (August-May) was estimated from the National Health Interview Survey data. GBS seasonality was determined using Poisson regression. GBS and P&I temporal clusters were identified using scan statistics. The association between P&I and GBS hospitalizations in the same month (concurrent) or in the following month (lagged) were determined using negative binomial regression. Vaccine coverage increased over the years (from 19.7% during 2004-2005 to 35.5% during 2008-2009 season) but GBS hospitalization did not follow a similar pattern. Overall, a significant correlation between monthly P&I and GBS hospitalizations was observed (Spearman's correlation coefficient=0.7016, p<0.0001). A significant (p=0.001) cluster of P&I hospitalizations during December 2004-March 2005 overlapped a significant (p=0.001) cluster of GBS hospitalizations during January 2005-February 2005. After accounting for effects of monthly vaccine coverage and age, P&I hospitalization was significantly associated (p<0.0001) with GBS hospitalization in the concurrent month but not with GBS hospitalization in the following month. Monthly vaccine coverage was not associated with GBS hospitalization in adjusted models (both concurrent and lagged). GBS hospitalizations demonstrated a seasonal pattern with winter months having higher rates compared to the month of June. P&I hospitalization rates were significantly correlated with hospitalization rates for GBS. Vaccine coverage did not significantly affect the rates of GBS hospitalization at the population level.

Cumulative risk of Guillain-Barré syndrome among vaccinated and unvaccinated populations during the 2009 H1N1 influenza pandemic

OBJECTIVES

We sought to assess risk of Guillain-Barré syndrome (GBS) among influenza A (H1N1) 2009 monovalent (pH1N1) vaccinated and unvaccinated populations at the end of the 2009 pandemic.

METHODS

We applied GBS surveillance data from a US population catchment area of 45 million from October 15, 2009, through May 31, 2010. GBS cases meeting Brighton Collaboration criteria were included. We calculated the incidence density ratio (IDR) among pH1N1 vaccinated and unvaccinated populations. We also estimated cumulative GBS risk using life table analysis. Additionally, we used vaccine coverage data and census population estimates to calculate denominators.

RESULTS

There were 392 GBS cases; 64 (16%) occurred after pH1N1vaccination. The vaccinated population had lower average risk (IDR = 0.83, 95% confidence interval = 0.63, 1.08) and lower cumulative risk (6.6 vs 9.2 cases per million persons, P = .012) of GBS.

CONCLUSIONS

Our findings suggest that at the end of the influenza season cumulative GBS risk was less among the pH1N1vaccinated than the unvaccinated population, suggesting the benefit of vaccination as it relates to GBS. The observed potential protective effect on GBS attributed to vaccination warrants further study.

Guillain-Barre syndrome, influenza, and influenza vaccination: the epidemiologic evidence

Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis worldwide, and is thought to be immune-mediated. It is preceded by upper respiratory or gastrointestinal infection in about two-thirds of cases and is associated with some viral infections, including influenza. GBS has also been associated with the 1976 swine-influenza vaccine. Thereafter, some studies have shown a small increased risk of GBS following receipt of seasonal and 2009 H1N1 monovalent influenza vaccines. Studies over the years have also shown an increased risk of GBS following influenza infection, and the magnitude of risk is several times greater than that following influenza vaccination. Because GBS is rare, and even rarer following vaccination, it is difficult to estimate precise risk. We try to shed light on the complex relationship of GBS and its association with influenza and influenza vaccines over the past 35 years.

Neurologic aspects of influenza viruses

Although influenza A and B viruses are primarily known as respiratory viruses and mainly infected only the upper respiratory tract in humans, patients with influenza often develop signs and symptoms that are not due to the respiratory system. Frequently individuals with influenza develop headaches, meningismus, and even seizures in addition to their typical respiratory symptoms. In the past decades, influenza viruses have also been associated with serious non-respiratory signs. The famous 1918 strain of influenza was associated with von Economo's encephalitis lethargica and postencephalitic parkinsonism. In the 1960s influenza virus infections in children were associated with Reye's syndrome characterized often by fatty non-inflammatory hepatic disease and an encephalopathy with marked non-inflammatory cerebral edema. Intermittently children with influenza develop focal myalgia and myositis. Guillain–Barré syndrome was epidemiologically associated with the 1978 killed influenza vaccine but not subsequent vaccines. Although occasional children with influenza have developed encephalopathy, from 2000 through 2004 there was an increase in the number of serious cases of acute necrotizing encephalopathy accompanying infection with the influenza A 2009 strain. The current H5N1 strain of bird influenza occasionally infects humans with a high mortality rate and some appear to have central nervous signs. This chapter explores what is known about these influenza neurologic associations.

Lack of association of Guillain-Barré syndrome with vaccinations

BACKGROUND

Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy, thought to be an autoimmune process. Although cases of GBS have been reported following a wide range of vaccines, a clear association has only been established with the 1976 H1N1 inactivated influenza vaccine.

METHODS

We identified hospitalized GBS cases from Kaiser Permanente Northern California (KPNC) from 1995 through 2006. The medical record of each suspected case was neurologist-reviewed according to the Brighton Collaboration GBS case definition; only confirmed cases were included in the analyses, and cases of Miller Fisher syndrome were excluded. Using a case-centered design, we compared the odds of vaccination in the 6 and 10 weeks prior to onset of GBS to the odds of vaccination during the same time intervals in all vaccinated individuals in the entire KPNC population.

RESULTS

We confirmed 415 incident cases of GBS (including Brighton levels 1, 2, and 3) during the study period (>30 million person-years). Incidence peaked during the winter months. The odds ratio of influenza vaccination within a 6-week interval prior to GBS, compared with the prior 9 months, was 1.1 (95% confidence interval [CI], .4-3.1). The risk in the 6-week interval compared to the prior 12 months for tetanus diphtheria combination, 23-valent pneumococcal polysaccharide, and for all vaccines combined was 1.4 (95% CI, .3-4.5), 0.7 (95% CI, .1-2.9), and 1.3 (95% CI, .8-2.3), respectively.

CONCLUSIONS

In this large retrospective study, we did not find evidence of an increased risk of GBS following vaccinations of any kind, including influenza vaccination.

[Guillain-Barré syndrome after exposure to influenza]

Guillain-Barré Syndrome (GBS) is an acquired, monophasic inflammatory polyradiculoneuritis of autoimmune origin, which occurs after infection and occasionally also after vaccination. Seasonal and pandemic influenza vaccines have in particular been implicated as triggers for GBS. However, a number of recent studies indicate that infection with influenza virus may also cause GBS. This review summarizes the epidemiological and experimental data of the association of GBS with exposure to influenza antigens by immunization (including vaccines against A/H1N1/2009) and infection. Vaccination against influenza is associated with a very low risk for the occurrence of GBS. In contrast infection with influenza may play a more important role as a triggering factor for GBS than previously assumed.

PCR based bronchoscopic detection of common respiratory pathogens in chronic cough: a case control study

BACKGROUND

Viral respiratory tract infection is the most frequent cause of acute cough and is reported at onset in about one third of patients with chronic cough. Persistent infection is therefore one possible explanation for the cough reflex hypersensitivity and pulmonary inflammation reported in chronic cough patients.

METHODS

Bronchoscopic endobronchial biopsies and bronchoalveolar lavage cell counts were obtained from ten healthy volunteers and twenty treatment resistant chronic cough patients (10 selected for lavage lymphocytosis). A screen for known respiratory pathogens was performed on biopsy tissue. Chronic cough patients also underwent cough reflex sensitivity testing using citric acid.

RESULTS

There was no significant difference in incidence of infection between healthy volunteers and chronic cough patients (p = 0.115) or non-lymphocytic and lymphocytic groups (p = 0.404). BAL cell percentages were not significantly different between healthy volunteers and chronic cough patients without lymphocytosis. Lymphocytic patients however had a significantly raised percentage of lymphocytes (p < 0.01), neutrophils (p < 0.05), eosinophils (p < 0.05) and decreased macrophages (p < 0.001) verses healthy volunteers. There was no significant difference in the cough reflex sensitivity between non-lymphocytic and lymphocytic patients (p = 0.536).

CONCLUSIONS

This study indicates latent infection in the lung is unlikely to play an important role in chronic cough, but a role for undetected or undetectable pathogens in either the lung or a distal site could not be ruled out.

TRIALS REGISTRATION

Current Controlled Trials ISRCTN62337037 & ISRCTN40147207.

Safety profile of oseltamivir during the 2009 influenza pandemic

PURPOSE

This study evaluated the safety of oseltamivir during the 2009 influenza pandemic.

METHODS

Case reports were obtained from the Roche safety database. The incidence of adverse events (AEs) during the pandemic (1 May 2009 to 31 December 2009) was compared with that beforehand (during previous influenza seasons) for USA and Japan only, as exposure data in other countries were collected inconsistently. Events with significantly higher reporting during the pandemic (lower bound of 95%CI for crude rate ratio >1) were analyzed further.

RESULTS

Global exposure in the pandemic and prepandemic periods was 18.3 and 64.7 million patients, respectively. In USA and Japan, exposure was 15.5 (1382 cases, 2225 events) and 62.0 million (8387 cases, 12,749 events), respectively. AEs with significantly higher reporting during the pandemic were generally consistent with influenza and its complications and/or with the circulation of a novel virus strain. As might be expected in a pandemic, mortality increased (crude rate ratio, 2.83; 95%CI, 2.23-3.59) versus the prepandemic period. Medical review of serious AEs (fatal or non-fatal outcome) found that most were consistent with pre-existing risk factors, underlying disease, and/or progression of influenza or its complications. Analysis of the remainder did not suggest a causal link with oseltamivir. A review of AEs in previously underexposed subpopulations did not support an association with oseltamivir.

CONCLUSIONS

During the first 8 months of the 2009 influenza pandemic, AEs reported in patients exposed to oseltamivir were consistent with the drug's labeled safety profile, underlying medical conditions, or infection with the pandemic virus.

Neurologic manifestations of novel influenza A (H1N1) virus infection in childhood

The neurologic manifestations and prognoses of a novel influenza A (H1N1) virus infection in previously healthy children were evaluated. Nose and throat swabs were retrieved from all patients who met the criteria of influenza-like illness. A real time reverse-transcriptase polymerase chain reaction assay was used to confirm the novel influenza A (H1N1) virus. This viral infection was evident in 240 children between October 10 and December 22, 2009. Neurologic findings were evident in 17 (7.08%) patients, aged between 4 months and 8 years. Nine were boys. Five patients manifested simple febrile seizures, seven manifested complex febrile seizures or additional afebrile seizures, and three manifested encephalopathy. Febrile status epilepticus and flaccid paralysis were diagnosed in one patient each. All were treated with oseltamivir. Fifteen of 17 patients demonstrated complete recovery. One undergoing follow-up with a diagnosis of Guillain-Barré syndrome manifested sequelae. One patient died because of septic shock and disseminated intravascular coagulation. We suggest that neurologic manifestations occur quite often in children aged less than 5 years with novel influenza A (H1N1) virus infection. Most infections were benign, although a severe course is possible, and sequelae may be encountered.

'Orf on the ear', in a patient with Guillain-Barré Syndrome

We report a case of orf on an ear in a patient admitted to hospital following the onset of Guillain-Barré syndrome. While the underlying causes of Guillain-Barré syndrome are not completely understood, immune stimulation appears to play a key role in pathogenesis. Any association between orf infection and Guillain-Barré syndrome has not been documented. A 22-year-old male sheep farmer, who was previously fit and well, presented to his local hospital with a 2-day history of distal upper and lower limb paraesthesia and weakness. He was transferred to a tertiary hospital where the diagnosis of Guillain-Barré syndrome was confirmed. History revealed that he had experienced a mild respiratory illness 3 weeks prior to presentation and an inflamed nodular lesion over his left ear, which had appeared 2 weeks prior to admission. Differential diagnoses of orf, atypical mycobacterial infection, subcutaneous mycosis and a squamous cell carcinoma were considered. Histopathology from a biopsy of the lesion was consistent with orf, which was confirmed by polymerase chain reaction testing. This case is of interest for two reasons: orf has not been described in association with Guillain-Barré syndrome, and orf on the ear is uncommon.

Acute motor axonal neuropathy associated with pandemic H1N1 influenza A infection

Background

Guillain–Barre syndrome (GBS) is a well known entity that has many infectious agents reported as antecedent events. The spectrum of GBS includes acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), acute motor sensory axonal neuropathy (AMSAN), and some other variants like Miller-Fisher syndrome (MFS).

Methods

Patient with AMAN variant of GBS after severe bilateral pneumonia and ARDS due to the novel pandemic H1N1 influenza A virus is presented.

Results

28-year-old white female was admitted to our Intensive Care Unit during the influenza pandemic because of severe ARDS due to bilateral pneumonia. The course of the disease was complicated with the new onset tetraplegia due to the AMAN variant of GBS. Treatment with plasma exchange was conducted and the patient had satisfactory recovery.

Conclusion

We report a case of AMAN variant of GBS associated with proven H1N1 influenza A infection. This virus has not been reported previously as the agent of antecedent infection that induced this disorder. Risk factors for other causes of ICU neuromuscular weakness are usually present in the ICU patients and should not be the reason for reluctance in active quest for GBS. Once the diagnosis of GBS is established or suspected the treatment with plasma exchange or intravenous immune globulin is indicated.

Guillain-Barré syndrome after exposure to influenza virus

Guillain-Barré syndrome (GBS) is an acute, acquired, monophasic autoimmune disorder of peripheral nerves that develops in susceptible individuals after infection and, in rare cases, after immunisation. Exposure to influenza via infection or vaccination has been associated with GBS. We review the relation between GBS and these routes of exposure. Epidemiological studies have shown that, except for the 1976 US national immunisation programme against swine-origin influenza A H1N1 subtype A/NJ/76, influenza vaccine has probably not caused GBS or, if it has, rates have been extremely low (less than one case per million vaccine recipients). By contrast, influenza-like illnesses seem to be relevant triggering events for GBS. The concerns about the risk of inducing GBS in mass immunisation programmes against H1N1 2009 do not, therefore, seem justified by the available epidemiological data. However, the experiences from the 1976 swine flu vaccination programme emphasise the importance for active and passive surveillance to monitor vaccine safety.

Investigation of the temporal association of Guillain-Barre syndrome with influenza vaccine and influenzalike illness using the United Kingdom General Practice Research Database

In 1976, the national swine influenza vaccination program in the United States was suspended because of an increased risk of Guillain-Barré syndrome. Subsequent studies of seasonal influenza vaccine have given conflicting results. The authors used the self-controlled case series method to investigate the relation of Guillain-Barré syndrome with influenza vaccine and influenzalike illness using cases recorded in the General Practice Research Database from 1990 to 2005 in the United Kingdom. The relative incidence of Guillain-Barré syndrome within 90 days of vaccination was 0.76 (95% confidence interval: 0.41, 1.40). In contrast, the relative incidence of Guillain-Barré syndrome within 90 days of an influenzalike illness was 7.35 (95% confidence interval: 4.36, 12.38), with the greatest relative incidence (16.64, 95% confidence interval: 9.37, 29.54) within 30 days. The relative incidence was similar (0.89, 95% confidence interval: 0.42, 1.89) when the analysis was restricted to a subset of validated cases. The authors found no evidence of an increased risk of Guillain-Barré syndrome after seasonal influenza vaccine. The finding of a greatly increased risk after influenzalike illness is consistent with anecdotal reports of a preceding respiratory illness in Guillain-Barré syndrome and has important implications for the risk/benefit assessment that would be carried out should pandemic vaccines be deployed in the future.

Guillain-Barré syndrome and influenza virus infection

BACKGROUND

In Western countries, the cause of 60% of all Guillain-Barré syndrome (GBS) cases remains unidentified. The number of cases of unidentified cause peaks in winter, and these cases are commonly preceded by respiratory tract infection or influenza-like illness. We investigated the triggering role of influenza virus infection.

METHODS

Of 405 patients with GBS who were admitted to a French reference center during 1996-2004, 234 had cases caused by an unidentified agent. We used time-series methods to study the correlation between the monthly incidence of such cases and influenza-like illnesses reported by the Sentinelles surveillance network. We analyzed anti-influenza antibodies using complement fixation testing and hemagglutination-inhibition assays. We studied etiological subgroups using Wilcoxon and Fisher's exact tests.

RESULTS

We found a positive association between the monthly incidence of GBS caused by an unidentified agent and reported influenza-like illnesses. Of 73 patients whose cases occurred during periods in which there was a possible link to influenza, 10 (13.7%) had serological evidence of recent influenza A, and 4 (5.5%) had serological evidence of influenza B. Eight of 10 influenza A-related cases occurred during "major" influenza seasons, and antibodies specific to the current epidemic strain were found in 9 cases. Most patients with influenza A-related cases were aged < 65 years, and none had antiganglioside antibodies. Influenza-related cases differed both from Campylobacter jejuni-related cases, with regard to the lack of need for mechanical ventilation (P = .014), and from the cases caused by an unidentified agent, with regard to the presence of preceding influenza-like illness or respiratory tract infection (P = .015) and longer time from the infectious event to GBS onset (P = .04).

CONCLUSIONS

Influenza viruses are infrequent triggering agents of GBS but may play a significant role during major influenza outbreaks. Influenza-related GBS displays specific features and is not associated with antiganglioside antibody response, which suggests the presence of underlying immune mechanisms.

Influenza-associated central nervous system dysfunction: a literature review

CONTEXT

Influenza is a viral pathogen that imposes an under-recognized burden of central nervous system (CNS) disease.

OBJECTIVE

To describe the epidemiology, clinical features and etiology of the CNS disease entities associated with influenza.

DATA SOURCES

English-language publications from MEDLINE.

DATA EXTRACTION

Articles were identified using "influenza, human"[Mesh] AND "nervous system diseases"[Mesh] and screened for inclusion based on relevance and scientific rigor.

RESULTS

Febrile seizure is the most frequently encountered influenza-associated CNS complication, with one in five children hospitalized with influenza experiencing one or more events. In most instances, symptoms resolve without neurological sequelae, although the risk for subsequent afebrile seizure may be increased. Influenza-associated encephalitis/encephalopathy is a less common but potentially more serious complication that is widely reported in Japanese populations, although cases from other East Asian countries, North America, and Europe have been described. Clinical manifestations are diverse, and typically involve febrile seizures and abnormal behaviors in mild cases, with rapid evolution through decreased consciousness to coma in severe forms. In cases of serious disease, the prognosis is often poor, with outcomes including death or severe neurological sequelae. Influenza is also a known trigger for a number of rarely encountered, yet often serious, CNS diseases, including the encephalopathic condition of Reye's syndrome, the peripheral neuropathy known as Guillain-Barré syndrome, and the lesser known complaints of Kleine-Levin syndrome and post-encephalitic Parkinson's disease.

CONCLUSIONS

Influenza imposes a sizeable burden of CNS disease. Increased awareness and monitoring of CNS function is indicated, especially in infants and young children.

Mycoplasma pneumoniae-an emerging extra-pulmonary pathogen

Mycoplasma is a well-recognised pathogen that colonises mucosal surfaces of humans and animals. Mycoplasma pneumoniae infects the upper and lower respiratory tracts of children and adults, leading to a wide range of respiratory and non-respiratory clinical conditions. M. pneumoniae infection is frequently considered in the differential diagnosis of patients with respiratory illnesses, and is commonly managed empirically with macrolides and fluoroquinolones. This contrasts with patients who present with non-respiratory symptoms in the context of a recent or current unrecognised M. pneumoniae infection, for whom this pathogen is rarely considered in the initial differential diagnosis. This review considers the microbiological, epidemiological, pathogenic and clinical features of this frequent pathogen that need to be considered in the differential diagnosis of respiratory and non-respiratory infections.

Guillain-Barré syndrome and preceding infection with campylobacter, influenza and Epstein-Barr virus in the general practice research database

Background

A number of infectious agents have previously been suggested as risk factors for the development of Guillain-Barré syndrome (GBS), but robust epidemiologic evidence for these associations is lacking.

Methods and Findings

We conducted a nested case-control study using data from the United Kingdom General Practice Research Database between 1991 and 2001. Controls were matched to cases on general practice clinic, sex, year of birth and date of outcome diagnosis in their matched case. We found positive associations between GBS and infection with Campylobacter, Epstein-Barr virus and influenza-like illness in the previous two months, as well as evidence of a protective effect of influenza vaccination. After correction for under-ascertainment of Campylobacter infection, the excess risk of GBS following Campylobacter enteritis was 60-fold and 20% of GBS cases were attributable to this pathogen.

Conclusions

Our findings indicate a far greater excess risk of GBS among Campylobacter enteritis patients than previously reported by retrospective serological studies. In addition, they confirm previously suggested associations between infection due to Epstein-Barr virus infection and influenza-like illness and GBS. Finally, we report evidence of a protective effect of influenza vaccination on GBS risk, which may be mediated through protection against influenza disease, or result from a lower likelihood of vaccination among those with recent infection. Cohort studies of GBS incidence in this population would help to clarify the burden of GBS due to influenza, and any potential protective effect of influenza vaccination.