Efficacy of Antitoxin Therapy in Treating Patients With Foodborne Botulism: A Systematic Review and Meta-analysis of Cases, 1923-2016

Investigations of Thiosemicarbazides as Botulinum Toxin Active-Site Inhibitors: Enzyme, Cellular, and Rodent Intoxication Studies

Botulinum neurotoxin type A (BoNT/A) is an exceptionally potent neurotoxin of great therapeutic value; however, it is also considered a weapon of mass destruction, as it is one of the most poisonous biological substances known to man. The etiology behind BoNT/A is its action as a zinc-dependent protease, which can cause extended paralysis through the cleavage of SNARE proteins. Thiosemicarbazones, known zinc chelators, provide a privileged scaffold that can be leveraged for the development of BoNT/A LC inhibitors. Through a combination of biochemical and kinetic assays, it was demonstrated that the thiosemicarbazone ZMC1, an antitumor agent, is an effective competitive inhibitor of the BoNT/A LC. Based on these results, a series of thiosemicarbazones were designed/synthesized using structure-based analysis and examined in enzyme activity and cell-based assays. From this screen, two analogues presented noteworthy cellular activity. The most potent inhibitors were then tested in a BoNT/A mouse lethality assay, providing statistically significant prolonged survival.

A Brief History of Polyclonal Antibody Therapies Against Bacterial and Viral Diseases Before COVID-19

The use of the serum or plasma of patients or animals who have recovered from an infectious disease, or had been immunized with a relevant antigen, to treat or prevent the same infection in others began in the late 1880s when French and German scientists uncovered, one step at a time, several of the elements of the immune system's response to infection. A key finding was that the damage caused by some bacteria depends upon their secreted toxins which can be neutralized by biologic agents. Antitoxins to diphtheria and tetanus began to be manufactured in large animals in France, Germany, and the US in the 1890s and were soon being used worldwide. The impact of diphtheria antitoxin on childhood mortality was profound. Shortly after the development of antitoxins, convalescent serum began to be used for its anti-bactericidal properties thus addressing serious infections caused by non-toxin-producing organisms. The effectiveness of antitoxins and antisera was demonstrated by examining mortality rates in hospitals before and after the introduction of antitoxins, by comparisons of treated and untreated patients, by comparing early and late treatment and dosage, by examining vital data mortality trends, and by several randomized and alternate assignment trials. Antitoxins continue to have a role in the rare cases of diphtheria and other conditions largely eradicated by immunization, but serum therapy nearly disappeared from the medical armamentarium with the development of antibiotics in the 1940s. Inasmuch as new human pathogens are now emerging with unprecedented regularity as seen in the recent COVID-19 pandemic, and because specific therapies are unlikely to be available for them, plasma-based antibody therapies are likely to again carve out a niche in infectious disease control.

Fecal Microbiota Transplantation for Severe Infant Botulism, China

Infant botulism in a 4-month-old boy in China who continued to excrete toxins for over a month despite antitoxin therapy was further treated with fecal microbiota transplantation. After treatment, we noted increased gut microbial diversity and altered fecal metabolites, which may help reduce intestinal pH and enhance anti-inflammatory capabilities.

Delayed onset post-traumatic wound botulism

A 41-year-old man developed rapidly progressive cranial neuropathies and muscle weakness followed by respiratory failure, requiring ventilation support. On examination, there was marked bilateral ptosis and ophthalmoplegia with bulbar, neck and proximal upper limb weakness. He had a recent open left humeral fracture that eventually required amputation. Despite immunoglobulin therapy, his progressive weakness continued. Multiple investigation results were inconclusive. Eventually, botulinum type A toxin was found positive, by which time the therapeutic window for antitoxin had passed. He continued on supportive management and was treated for concomitant infections and nosocomial illnesses. He was subsequently weaned from respiratory support and has made a good neurological recovery.

From Beauty to Botulism: A Case Report Highlighting the Rare Risk of Botox Administration

Botox (onabotulinumtoxinA) is a pharmaceutical approved by the Food and Drug Administration (FDA) for use in both cosmetic and therapeutic applications. Despite its increasing use worldwide, Botox carries a rare but potentially life-threatening risk of iatrogenic botulism. This condition, although treatable with antitoxin if promptly recognized, presents a diagnostic challenge to healthcare providers due to its rarity, lack of awareness, and diverse clinical presentations. Here, we present a case of iatrogenic botulism from Botox injections administered in Istanbul, Turkey, in a healthy 47-year-old female. Prompt administration of antitoxin led to remarkable clinical improvement. This case underscores the importance of vigilance among healthcare providers in recognizing and promptly treating iatrogenic botulism, particularly in patients with recent Botox use. Given that the majority of reported cases of iatrogenic botulism occur outside the United States, this case raises concerns about the need for stricter regulations and oversight of Botox administration worldwide.

An early scoring system to predict mechanical ventilation for botulism: a single-center-based study

BACKGROUND

Early identification of patients requiring ventilator support will be beneficial for the outcomes of botulism. The present study aimed to establish a new scoring system to predict mechanical ventilation (MV) for botulism patients.

METHODS

A single-center retrospective study was conducted to identify risk factors associated with MV in botulism patients from 2007 to 2022. Univariate analysis and multivariate logistic regression analysis were used to screen out risk factors for constructing a prognostic scoring system. The area under the receiver operating characteristic (ROC) curve was calculated.

RESULTS

A total of 153 patients with botulism (66 males and 87 females, with an average age of 43 years) were included. Of these, 49 patients (32.0%) required MV, including 21 (13.7%) with invasive ventilation and 28 (18.3%) with non-invasive ventilation. Multivariate analysis revealed that botulinum toxin type, pneumonia, incubation period, degree of hypoxia, and severity of muscle involvement were independent risk factors for MV. These risk factors were incorporated into a multivariate logistic regression analysis to establish a prognostic scoring system. Each risk factor was scored by allocating a weight based on its regression coefficient and rounded to whole numbers for practical utilization ([botulinum toxin type A: 1], [pneumonia: 2], [incubation period ≤1 day: 2], [hypoxia <90%: 2], [severity of muscle involvement: grade II, 3; grade III, 7; grade IV, 11]). The scoring system achieved an area under the ROC curve of 0.82 (95% CI 0.75-0.89, P<0.001). At the optimal threshold of 9, the scoring system achieved a sensitivity of 83.7% and a specificity of 70.2%.

CONCLUSION

Our study identified botulinum toxin type, pneumonia, incubation period, degree of hypoxia, and severity of muscle involvement as independent risk factors for MV in botulism patients. A score ≥9 in our scoring system is associated with a higher likelihood of requiring MV in botulism patients. This scoring system needs to be validated externally before it can be applied in clinical settings.

New approach to generating of human monoclonal antibodies specific to the proteolytic domain of botulinum neurotoxin A

Introduction

Botulinum neurotoxins (BoNTs) cause botulism and are the most potent natural toxins known. Immunotherapy with neutralizing monoclonal antibodies (MAbs) is considered to be the most effective immediate response to BoNT exposure. Hybridoma technology remains the preferred method for producing MAbs with naturally paired immunoglobulin genes and with preserved innate functions of immune cells. The affinity-matured human antibody repertoire may be ideal as a source for antibody therapeutics against BoNTs. In an effort to develop novel BoNT type A (BoNT/A) immunotherapeutics, sorted by flow cytometry plasmablasts and activated memory B cells from a donor repeatedly injected with BoNT/A for aesthetic botulinum therapy could be used due to obtain hybridomas producing native antibodies.

Methods

Plasmablasts and activated memory B-cells were isolated from whole blood collected 7 days after BoNT/A injection and sorted by flow cytometry. The sorted cells were then electrofused with the K6H6/B5 cell line, resulting in a producer of native human monoclonal antibodies (huMAbs). The 3 antibodies obtained were then purified by affinity chromatography, analyzed for binding by Western blot assay and neutralization by FRET assay.

Results

We have succeeded in creating 3 hybridomas that secrete huMAbs specific to native BoNT/A and the proteolytic domain (LC) of BoNT/A. The 1B9 antibody also directly inhibited BoNT/A catalytic activity in vitro.

Conclusion

The use activated plasmablasts and memory B-cells isolated at the peak of the immune response (at day 7 of immunogenesis) that have not yet completed the terminal stage of differentiation but have undergone somatic hypermutation for hybridization allows us to obtain specific huMAbs even when the immune response of the donor is weak (with low levels of specific antibodies and specific B-cells in blood). A BoNT/A LC-specific antibody is capable of effectively inhibiting BoNT/A by mechanisms not previously associated with antibodies that neutralize BoNT. Antibodies specific to BoNT LC can be valuable components of a mixture of antibodies against BoNT exposure.

Tetanus toxin and botulinum neurotoxin-derived fusion molecules are effective bivalent vaccines

Tetanus toxin (TeNT) and botulinum neurotoxins (BoNTs) are neuroprotein toxins, with the latter being the most toxic known protein. They are structurally similar and contain three functional domains: an N-terminal catalytic domain (light chain), an internal heavy-chain translocation domain (HN domain), and a C-terminal heavy chain receptor binding domain (Hc domain or RBD). In this study, fusion functional domain molecules consisting of the TeNT RBD (THc) and the BoNT/A RBD (AHc) (i.e., THc-Linker-AHc and AHc-Linker-THc) were designed, prepared, and identified. The interaction of each Hc domain and the ganglioside receptor (GT1b) or the receptor synaptic vesicle glycoprotein 2 (SV2) was explored in vitro. Their immune response characteristics and protective efficacy were investigated in animal models. The recombinant THc-linker-AHc and AHc-linker-THc proteins with the binding activity had the correct size and structure, thus representing novel subunit vaccines. THc-linker-AHc and AHc-linker-THc induced high levels of specific neutralizing antibodies, and showed strong immune protective efficacy against both toxins. The high antibody titers against the two novel fusion domain molecules and against individual THc and AHc suggested that the THc and AHc domains, as antigens in the fusion functional domain molecules, do not interact with each other and retain their full key epitopes responsible for inducing neutralizing antibodies. Thus, the recombinant THc-linker-AHc and AHc-linker-THc molecules are strong and effective bivalent biotoxin vaccines, protecting against two biotoxins simultaneously. Our experimental design will be valuable to develop recombinant double-RBD fusion molecules as potent bivalent subunit vaccines against bio-toxins. KEY POINTS: • Double-RBD fusion molecules from two toxins had the correct structure and activity. • THc-linker-AHc and AHc-linker-THc efficiently protected against both biotoxins. • Such bivalent biotoxin vaccines based on the RBD are a valuable experimental design.

Pathogenicity and virulence of Clostridium botulinum

Clostridium botulinum, a polyphyletic Gram-positive taxon of bacteria, is classified purely by their ability to produce botulinum neurotoxin (BoNT). BoNT is the primary virulence factor and the causative agent of botulism. A potentially fatal disease, botulism is classically characterized by a symmetrical descending flaccid paralysis, which is left untreated can lead to respiratory failure and death. Botulism cases are classified into three main forms dependent on the nature of intoxication; foodborne, wound and infant. The BoNT, regarded as the most potent biological substance known, is a zinc metalloprotease that specifically cleaves SNARE proteins at neuromuscular junctions, preventing exocytosis of neurotransmitters, leading to muscle paralysis. The BoNT is now used to treat numerous medical conditions caused by overactive or spastic muscles and is extensively used in the cosmetic industry due to its high specificity and the exceedingly small doses needed to exert long-lasting pharmacological effects. Additionally, the ability to form endospores is critical to the pathogenicity of the bacteria. Disease transmission is often facilitated via the metabolically dormant spores that are highly resistant to environment stresses, allowing persistence in the environment in unfavourable conditions. Infant and wound botulism infections are initiated upon germination of the spores into neurotoxin producing vegetative cells, whereas foodborne botulism is attributed to ingestion of preformed BoNT. C. botulinum is a saprophytic bacterium, thought to have evolved its potent neurotoxin to establish a source of nutrients by killing its host.

Food-borne botulism outbreak during the Rugby World Cup linked to marinated sardines in Bordeaux, France, September 2023

In September 2023, a botulism outbreak affecting 15 individuals occurred in Bordeaux, France, during the Rugby World Cup. We report on eight individuals from four different countries on two continents admitted to the intensive care unit at our hospital, where six required invasive mechanical ventilation. Cases reported consuming locally produced canned sardines at a restaurant. This report highlights the importance of rapid, worldwide alerts from health authorities to prevent severe consequences of such outbreaks, particularly during events attracting international visitors.

[Clinical and neuroelectrophysiological features of botulism in children: an analysis of eight sporadic cases]

OBJECTIVES

To study the clinical and neuroelectrophysiological features of botulism in children.

METHODS

A retrospective analysis was conducted on the clinical data of eight children who were diagnosed with botulism in the Department of Neurology, Hunan Children's Hospital, from August 2015 to October 2022.

RESULTS

All eight children were found to have symmetrical cranial nerve palsy and flaccid paralysis of the extremities, with a descending pattern. Seven children presented with respiratory muscle paralysis. Electrophysiological examinations revealed decreased compound muscle action potential (CMAP) amplitudes in 5 children, increased CMAP amplitudes exceeding 40.0% in 6 children during high-frequency repetitive nerve stimulation, and short duration, low amplitude, and polyphasic motor unit action potentials in 4 children.

CONCLUSIONS

The main clinical features of botulism in children include symmetric, descending flaccid paralysis starting from cranial nerves, with the possibility of respiratory muscle paralysis. Electrophysiological abnormalities associated with it include decreased CMAP amplitudes, increased CMAP amplitudes during high-frequency repetitive nerve stimulation, and short duration, low amplitude, and polyphasic motor unit action potentials.

Foodborne botulism and the importance of recognizing the disease in the emergency department: a case report

BACKGROUND

Botulism is a rare neuroparalytic disease that has only presented itself 19 times in the last 30 years in Belgium. Patients present to emergency services with a wide range of complaints. Foodborne botulism is a forgotten yet life-threatening disease.

CASE PRESENTATION

We describe a case of a Caucasian female in her 60s that presented to the emergency with reflux with nausea and spasmodic epigastric pain, no vomiting, dry mouth, and weakness in both legs. The symptoms started after ingestion of Atlantic wolffish. After exclusion of other more common causes, foodborne botulism was suspected. The patient was admitted to the intensive care unit for mechanical ventilation. Following treatment with trivalent botulinum antitoxin, she made a full neurologic recovery.

CONCLUSION

It is important to rapidly recognize the possible diagnosis of botulism even if the neurological symptoms are not dominant. Rapid neurologic dysfunction and respiratory difficulties starts between 6 and 72 hours after ingestion. The decision to administer antitoxins should, however, be based on the presumptive clinical diagnosis and diagnosis should not delay therapy.

Botulism in Spain: Epidemiology and Outcomes of Antitoxin Treatment, 1997-2019

BACKGROUND

Botulism is a low incidence but potentially fatal infectious disease caused by neurotoxins produced mainly by Clostridium botulinum. There are different routes of acquisition, food-borne and infant/intestinal being the most frequent presentation, and antitoxin is the treatment of choice in all cases. In Spain, botulism is under surveillance, and case reporting is mandatory.

METHODS

This retrospective study attempts to provide a more complete picture of the epidemiology of botulism in Spain from 1997 to 2019 and an assessment of the treatment, including the relationship between a delay in antitoxin administration and the length of hospitalization using the Cox proportional hazards test and Kruskal-Wallis test, and an approach to the frequency of adverse events, issues for which no previous national data have been published.

RESULTS

Eight of the 44 outbreaks were associated with contaminated commercial foods involving ≤7 cases/outbreak; preserved vegetables were the main source of infection, followed by fish products; early antitoxin administration significantly reduces the hospital stay, and adverse reactions to the antitoxin affect around 3% of treated cases.

Antidotal treatment of botulism in rats by continuous infusion with 3,4-diaminopyridine

Botulinum neurotoxins (BoNTs) are highly potent, select agent toxins that inhibit neurotransmitter release at motor nerve terminals, causing muscle paralysis and death by asphyxiation. Other than post-exposure prophylaxis with antitoxin, the only treatment option for symptomatic botulism is intubation and supportive care until recovery, which can require weeks or longer. In previous studies, we reported the FDA-approved drug 3,4-diaminopyridine (3,4-DAP) reverses early botulism symptoms and prolongs survival in lethally intoxicated mice. However, the symptomatic benefits of 3,4-DAP are limited by its rapid clearance. Here we investigated whether 3,4-DAP could sustain symptomatic benefits throughout the full course of respiratory paralysis in lethally intoxicated rats. First, we confirmed serial injections of 3,4-DAP stabilized toxic signs and prolonged survival in rats challenged with 2.5 LD50 BoNT/A. Rebound of toxic signs and death occurred within hours after the final 3,4-DAP treatment, consistent with the short half-life of 3,4-DAP in rats. Based on these data, we next investigated whether the therapeutic benefits of 3,4-DAP could be sustained throughout the course of botulism by continuous infusion. To ensure administration of 3,4-DAP at clinically relevant doses, three infusion dose rates (0.5, 1.0 and 1.5 mg/kg∙h) were identified that produced steady-state serum levels of 3,4-DAP consistent with clinical dosing. We then compared dose-dependent effects of 3,4-DAP on toxic signs and survival in rats intoxicated with 2.5 LD50 BoNT/A. In contrast to saline vehicle, which resulted in 100% mortality, infusion of 3,4-DAP at ≥ 1.0 mg/kg∙h from 1 to 14 d after intoxication produced 94.4% survival and full resolution of toxic signs, without rebound of toxic signs after infusion was stopped. In contrast, withdrawal of 3,4-DAP infusion at 5 d resulted in re-emergence of toxic sign and death within 12 h, confirming antidotal outcomes require sustained 3,4-DAP treatment for longer than 5 d after intoxication. We exploited this novel survival model of lethal botulism to explore neurophysiological parameters of diaphragm paralysis and recovery. While neurotransmission was nearly eliminated at 5 d, neurotransmission was significantly improved at 21 d in 3,4-DAP-infused survivors, although still depressed compared to naïve rats. 3,4-DAP is the first small molecule to reverse systemic paralysis and promote survival in animal models of botulism, thereby meeting a critical treatment need that is not addressed by post-exposure prophylaxis with conventional antitoxin. These data contribute to a growing body of evidence supporting the use of 3,4-DAP to treat clinical botulism.

Recent Trends in Protective Textiles against Biological Threats: A Focus on Biological Warfare Agents

The rising threats to worldwide security (affecting the military, first responders, and civilians) urge us to develop efficient and versatile technological solutions to protect human beings. Soldiers, medical personnel, firefighters, and law enforcement officers should be adequately protected, so that their exposure to biological warfare agents (BWAs) is minimized, and infectious microorganisms cannot be spread so easily. Current bioprotective military garments include multilayered fabrics integrating activated carbon as a sorptive agent and a separate filtrating layer for passive protection. However, secondary contaminants emerge following their accumulation within the carbon filler. The clothing becomes too heavy and warm to wear, not breathable even, preventing the wearer from working for extended hours. Hence, a strong need exists to select and/or create selectively permeable layered fibrous structures with bioactive agents that offer an efficient filtering capability and biocidal skills, ensuring lightweightness, comfort, and multifunctionality. This review aims to showcase the main possibilities and trends of bioprotective textiles, focusing on metal-organic frameworks (MOFs), inorganic nanoparticles (e.g., ZnO-based), and organic players such as chitosan (CS)-based small-scale particles and plant-derived compounds as bioactive agents. The textile itself should be further evaluated as the foundation for the barrier effect and in terms of comfort. The outputs of a thorough, standardized characterization should dictate the best elements for each approach.

Adult Intestinal Toxemia Botulism in a Patient With Crohn's Disease

Adult intestinal toxemia botulism (ITB) is a rare illness that can be fatal if not recognized. ITB can occur when botulinum neurotoxin–producing clostridia colonize the intestine. Underlying intestinal abnormalities associated with dysbiosis are likely a prerequisite for colonization. Dysbiosis seems necessary for spore germination and neurotoxin production. Botulism neurotoxins are the most lethal poisons known and are classified into 7 serotypes: A through G. The clinical presentation consists of cranial nerve abnormalities and descending flaccid paralysis. Prompt recognition and treatment with botulism antitoxin and supportive measures is often successful, but delayed recognition can be fatal. In this study, we present a case of a 40-year-old woman with Crohn's disease who developed ITB. This is the first case in literature to report adult intestinal botulism from Clostridium botulinum producing toxin B and F in the same patient.

Wound Botulism Among Persons Who Inject Black Tar Heroin in New Mexico, 2016

Outbreaks of wound botulism are rare, but clinicians and health departments should maintain suspicion for signs, symptoms, and risk factors of wound botulism among persons who inject drugs in order to initiate treatment quickly. This report describes an outbreak of three wound botulism cases among persons in two adjacent counties who injected drugs. Provisional information about these cases was previously published in the CDC National Botulism Surveillance Summary. All three cases in this outbreak were laboratory-confirmed, including one case with detection of botulinum toxin type A in a wound culture sample taken 43 days after last possible heroin exposure. Findings highlight the delay in diagnosis which led to prolonged hospitalization and the persistence of botulinum toxin in one patient.

Outbreak of foodborne botulism in Alexandria, Egypt: modulating indications for administration of heptavalent botulinum antitoxin

In October 2019, ninety-four patients were admitted into Alexandria Poison Center (APC) with a history of ingestion of Feseekh (salted fish). In an attempt to allocate the resources, not all patients were given HBAT (botulism antitoxin heptavalent (A, B, C, D, E, F, G) equine immediately. The current study aimed to portray the clinical characteristics of the cases, explore the possible relation between these characteristics and necessity of HBAT administration, explore the reliability of mouse lethal test, and establish a clinical guide for management including preservation of resources. The current prospective study included 94 patients who were admitted to Alexandria Poison Center (APC) in the period from the 29^th of September to the 27^th of October 2019. The patients' data were recorded using a checklist that includes: personal data, past medical history, clinical assessment, investigations, treatment, and the outcome. The checklist was carried out to assess and follow up each patient. Hospitalized patients were categorized according to symptoms consistent with botulism. The equine HBAT, made by Emergent BioSolutions Canada Inc. (formerly Cangene Corporation), was used in the treatment. HBAT was given to thirty-four patients (36.2%) only out of the total admission. However, eighty-two (87.2%) of patients were completely cured, whereas ten patients (10.6%) were discharged with mild neurological sequels and death occurred only in two cases (2.2%). Sixty cases (63.8%) with suspected foodborne botulism could be managed by supportive treatment only with no need for HBAT, while patients with evident neurological signs received HBAT immediately.

Mild Botulism From Illicitly Brewed Alcohol in a Large Prison Outbreak in Mississippi

Botulism is typically described as a rapidly progressing, severe neuroparalytic disease. Foodborne botulism is transmitted through consuming food or drink that has been contaminated with botulinum toxin. During a botulism outbreak linked to illicitly brewed alcohol (also known as “hooch” or “pruno”) in a prison, 11 (35%) of 31 inmates that consumed contaminated hooch had mild illnesses. This includes 2 inmates with laboratory confirmed botulism. The most frequently reported signs and symptoms among the 11 patients with mild illness included dry mouth (91%), hoarse voice (91%), difficulty swallowing (82%), fatigue (82%), and abdominal pain (82%). Foodborne botulism is likely underdiagnosed and underreported in patients with mild illness. Botulism should be considered on the differential diagnosis for patients with cranial nerve palsies.

Foodborne Botulism in Western Romania: Ten Years' Experience at a Tertiary Infectious Disease Hospital

OBJECTIVES

The purpose of this study was to analyze epidemiological data concerning foodborne botulism in Western Romania over the last decade. Botulism, the toxin formed by the bacterium Clostridium botulinum, results in a neuroparalytic disorder capable of severe clinical progression that begins in the cranial nerves and progressively descends. Preventing progression to a severe case entails timely diagnosis since curative assets are restricted. Ingesting food containing a preformed toxin (foodborne botulism) is the most typical form.

METHODS

Medical records were retrospectively analyzed from 2010 to 2020 for all food botulism cases. A seroneutralization test was performed with type A, B and E anti-botulinum sera to establish the kind of toxin involved.

RESULTS

Overall, 18 cases of foodborne botulism were admitted to the hospital during this period and confirmed by laboratory analysis. Most of the participants in our study were men (61.1%), and 77.8% of the total lived in rural areas. All the participants showed classic symptoms of botulism, and dysphagia was present in all cases. The trivalent ABE antitoxin was administered by the hospital, and toxin type B was isolated in all patients. The main sources of the toxin were pork, ham and canned pork meat.

CONCLUSIONS

Stronger efforts are needed to foster community awareness of foodborne botulism, particularly in home-preserved food.

A Novel Running Wheel Mouse Model for Botulism and Its Use for the Evaluation of Postsymptom Antitoxin Efficacy

Antitoxin is currently the only approved therapy for botulinum intoxications. The efficacy of antitoxin preparations is evaluated in animals. However, while in practice antitoxin is administered to patients only after symptom onset, in most animal studies, it is tested in relation to time postintoxication. This may be attributed to difficulties in quantitating early botulism symptoms in animals. In the current study, a novel system based on high-resolution monitoring of mouse activity on a running wheel was developed to allow evaluation of postsymptom antitoxin efficacy. The system enables automatic and remote monitoring of 48 mice simultaneously. Based on the nocturnal activity patterns of individual naive mice, two criteria were defined as the onset of symptoms. Postsymptom treatment with a human-normalized dose of antitoxin was fully protective in mice exposed to 4 50% lethal doses (LD₅₀s) of botulinum neurotoxin serotype A (BoNT/A) and BoNT/B. Moreover, for the first time, a high protection rate was obtained in mice treated postsymptomatically, following a challenge with BoNT/E, the fastest-acting BoNT. The running wheel system was further modified to develop a mouse model for the evaluation of next-generation therapeutics for progressive botulism at time points where antitoxin is not effective. Exposure of mice to 0.3 LD₅₀ of BoNT/A resulted in long-lasting paralysis and a reduction in running activity for 16 to 18 days. Antitoxin treatment was no longer effective when administered 72 h postintoxication, defining the time window to evaluate next-generation therapeutics. Altogether, the running wheel systems presented herein offer quantitative means to evaluate the efficacy of current and future antibotulinum drugs.

Suspected botulism outbreak after the consumption of vegetarian pâté in the south of Viet Nam

Botulism and other botulinum neurotoxins-producing clostridia  are potentially life-threatening diseases caused by toxins produced by Clostridium botulinum. Here we reported a case series of six patients who presented with botulism following ingestion of commercially made pâté. The key features of presentation were acute onset of bilateral cranial nerve palsies and symmetrical descending weakness in the absence of fever resulting in the need for mechanical ventilation in all six patients. The clinical diagnosis of botulism was confirmed through the identification of C. botulinum from the suspected food source.  Given that botulinum antitoxin was not available in Vietnam at the time, and their severe status, all patients received a trial of plasma exchange therapy, but no clear benefit was seen. Due to its rarity, diagnosing botulism is a challenge, demanding high clinical suspicion. Successful outcomes depend upon early recognition and rapid initiation of specific treatment with botulinum antitoxin. There is a need to improve global access to antitoxin.  These cases, the first in Viet Nam, serve as a reminder of the need to maintain the highest possible food hygiene and preservation practices.

Clinical Guidelines for Diagnosis and Treatment of Botulism, 2021

Botulism is a rare, neurotoxin-mediated, life-threatening disease characterized by flaccid descending paralysis that begins with cranial nerve palsies and might progress to extremity weakness and respiratory failure. Botulinum neurotoxin, which inhibits acetylcholine release at the neuromuscular junction, is produced by the anaerobic, gram-positive bacterium Clostridium botulinum and, rarely, by related species (C. baratii and C. butyricum). Exposure to the neurotoxin occurs through ingestion of toxin (foodborne botulism), bacterial colonization of a wound (wound botulism) or the intestines (infant botulism and adult intestinal colonization botulism), and high-concentration cosmetic or therapeutic injections of toxin (iatrogenic botulism). In addition, concerns have been raised about the possibility of a bioterrorism event involving toxin exposure through intentional contamination of food or drink or through aerosolization. Neurologic symptoms are similar regardless of exposure route. Treatment involves supportive care, intubation and mechanical ventilation when necessary, and administration of botulinum antitoxin. Certain neurological diseases (e.g., myasthenia gravis and Guillain-Barré syndrome) have signs and symptoms that overlap with botulism. Before the publication of these guidelines, no comprehensive clinical care guidelines existed for treating botulism. These evidence-based guidelines provide health care providers with recommended best practices for diagnosing, monitoring, and treating single cases or outbreaks of foodborne, wound, and inhalational botulism and were developed after a multiyear process involving several systematic reviews and expert input.

Management of an outbreak of botulism with benign clinical presentation

Botulism is a life-threatening presynaptic disorder of the neuromuscular transmission produced by the neurotoxin elaborated by the botulinum neurotoxin-producing clostridia. We describe the management of a case series of 14 patients, members of 5 different families that were exposed to home-canned tuna and developed symptoms compatible with a mild clinical presentation of foodborne botulism. The electrophysiological study of the index case represented a reliable diagnostic test as it demonstrated a slight presynaptic dysfunction of the neuromuscular junction. Definite diagnosis was later confirmed by microbiological tests. Out of 14, only 3 patients presenting with a shorter period from symptom onset and with signs of multiple cranial neuropathies received botulinum antitoxin. All the patients remained stable and recovered progressively. Treatment with antitoxin may not be necessary in patients with late-presenting disease and mild and stable clinical picture.

Neuroinfectious Disease Emergencies

Neuroinfectious diseases can affect immunocompetent and immunosuppressed individuals and cause a variety of emergencies including meningitis, encephalitis, and abscess. Neurologic infections are frequently complicated by secondary injuries that also present emergently such as cerebrovascular disease, acute obstructive hydrocephalus, and seizure. In most cases, timely recognition and early treatment of infection can improve the morbidity and mortality of infectious neurologic emergencies.

A Case Report of Wound Botulism - Rare Disease on the Rise with the Opioid Crisis

Wound botulism is a rare, underrecognized life-threatening illness caused by a toxin produced by Clostridium botulinum, a spore-forming anaerobic bacterium. Approximately 20 cases are reported in the United States each year, mostly from California. Most wound botulism cases occur in drug injectors, particularly among those using black tar heroin. The initial presentation of botulism may overlap with other diagnoses, including opioid intoxication and pre-existing neurological disease, making accurate diagnosis difficult. A healthy 40-year-old patient with a history of injecting black tar heroin presented to an emergency department complaining of generalized weakness and throat discomfort. He was given antibiotics and was sent home. The next day, the patient presented to another emergency department with additional complaints of slurred speech and blurring of vision. He was admitted for a possible cerebrovascular injury. In the absence of positive findings from laboratory or imaging studies, botulism was considered. The patient decompensated and was intubated. Botulism antitoxin was given, and the patient eventually recovered. Prompt decision-making based on clinical suspicion and an informed presumptive diagnosis, administration of botulism antitoxin, and aggressive provision of supportive care can arrest the progression of paralysis and be life-saving. With the rise of opioid use in the United States, leading to a reversion to heroin as a cheaper form of opioids, cases of wound botulism may be on the rise. Clinician attentiveness to obtaining substance history and being aware of botulism presentation may lead to life-saving treatments for these patients.

Botulism outbreak after the consumption of vegetarian pâté in the south of Viet Nam

Botulism is a potentially life-threatening disease caused by toxins produced by Clostridium botulinum. Here we reported a case series of six patients who presented with botulism following ingestion of commercially made pâté. The key features of presentation were acute onset of bilateral cranial nerve palsies and symmetrical descending weakness in the absence of fever resulting in the need for mechanical ventilation in all six patients. The clinical diagnosis of botulism was confirmed through the identification of C. botulinum from the suspected food source.  Given that botulinum antitoxin was not available in Vietnam at the time, and their severe status, all patients received a trial of plasma exchange therapy, but no clear benefit was seen. Due to its rarity, diagnosing botulism is a challenge, demanding high clinical suspicion. Successful outcomes depend upon early recognition and rapid initiation of specific treatment with botulinum antitoxin. There is a need to improve global access to antitoxin.  These cases, the first in Viet Nam, serve as a reminder of the need to maintain the highest possible food hygiene and preservation practices.

Influence of aerodynamic particle size on botulinum neurotoxin potency in mice

OBJECTIVE

For many agents, the aerodynamic particle size can affect both the virulence and disease course in animal models. Botulinum neurotoxins (BoNTs), which are widely known as potential bioterrorism agents, have been shown to be toxic via multiple routes of exposure, including small particle inhalation (1-3 µm MMAD). However, the impact of larger particle sizes on the potency of BoNT has not been previously reported. In this study, we compared the potency of BoNT in small and large particle aerosols.

MATERIALS AND METHODS

Outbred mice (ICR (CD-1^®)) were exposed to BoNT-containing aerosols with differing mass median aerodynamic diameters (MMADs) of 1.1, 4.9, and 7.6 microns. The effects of bioaerosol sampler and inhalation exposure modality were studied.

RESULTS AND DISCUSSION

Collecting aerosolized BoNT onto gelatin filters or into liquid impingers resulted in equivalent estimates of aerosol concentration. Nose-only and whole-body inhalation exposure resulted in nearly identical estimates of the median lethal dose (LD₅₀). The LD₅₀ for inhaled BoNT increased approximately 50-fold when the median aerodynamic particle size was increased from 1.1 to 4.9 µm, from 139 (95% CI: 111-185) to 7324 (95% CI: 4287-10 891) mouse intraperitoneal median lethal doses (MIPLD₅₀). These results demonstrate the importance of aerodynamic particle size and regional deposition patterns with regards to BoNT inhalational toxicity.

CONCLUSIONS

These data will be useful for medical countermeasure development, as well as biodefense preparedness modeling by demonstrating that the estimates of dose and toxicity of an inhaled aerosol containing BoNT can be significantly affected by a range of factors.

Safety and Clinical Outcomes of an Equine-derived Heptavalent Botulinum Antitoxin Treatment for Confirmed or Suspected Botulism in the United States

BACKGROUND

Botulism is a rare, life-threatening paralytic illness. Botulism Antitoxin Heptavalent (A,B,C,D,E,F,G)-(Equine) (BAT) manufactured by Emergent BioSolutions Canada Inc is an equine-derived heptavalent botulinum antitoxin product indicated for the treatment of symptomatic botulism following documented or suspected exposure to botulinum neurotoxin serotypes A-G in adults and pediatric patients. BAT product was US-licensed in 2013.

METHODS

In the United States, from October 2014 through July 2017, safety and clinical outcomes data were collected under a registry for patients treated with BAT product.

RESULTS

Registry patients had a median age of 51 years (range, 32 days to 92 years). Among 162 patients, 7 (4.3%) experienced BAT product-related serious adverse events, including 1 (0.6%) report each of pneumonia, pneumonia aspiration, ventricular tachycardia, upper gastrointestinal hemorrhage, anaphylactic reaction, acute kidney injury, and acute myocardial infarction. Thirty-one (19.1%) patients had 41 BAT product-related adverse events. Six (3.7%) deaths were reported in the registry. All deaths were attributed to the underlying illness and were assessed as unlikely related to BAT product. Among 113 (69.8%) patients with a final diagnosis of botulism, those treated early (≤2 days) spent fewer days in the hospital (5 vs 15.5 days), in the intensive care unit (ICU) (4 vs 12 days), and on mechanical ventilation (6 vs 14.5 days) than those treated late (>2 days), respectively.

CONCLUSIONS

BAT product was well tolerated in patients. Treatment with BAT product at ≤2 days of symptom onset was associated with shorter hospital and ICU stays, and shorter duration and need for mechanical ventilation, showing clinical benefit associated with early treatment.

Botulism outbreak after the consumption of vegetarian pâté in the south of Viet Nam

Botulism is a potentially life-threatening disease caused by toxins produced by Clostridium botulinum. Here we reported a case series of six patients who presented with botulism following ingestion of commercially made pâté. The key features of presentation were acute onset of bilateral cranial nerve palsies and symmetrical descending weakness in the absence of fever resulting in the need for mechanical ventilation in all six patients. The clinical diagnosis of botulism was confirmed through the identification of C. botulinum from the suspected food source.  Given that botulinum antitoxin was not available in Vietnam at the time, and their severe status, all patients received a trial of plasma exchange therapy, but no clear benefit was seen. Due to its rarity, diagnosing botulism is a challenge, demanding high clinical suspicion. Successful outcomes depend upon early recognition and rapid initiation of specific treatment with botulinum antitoxin. There is a need to improve global access to antitoxin.  These cases, the first in Viet Nam, serve as a reminder of the need to maintain the highest possible food hygiene and preservation practices.

Prevalence, Risk Factors, and Epidemiology of Food-borne Botulism in Iran

BACKGROUND

Botulism is a severe neuroparalytic disease caused by toxins produced by several Clostridium species. This work presents the surveillance results of botulism in Iran, with the distribution of the cases by regions and by vehicle of transmission.

METHODS

We describe the findings of the Centers for Disease Control and Prevention (CDC) surveillance on 2037 suspected cases of food-borne botulism during 2007-2017.

RESULTS

A total of 252 (12.3%) cases were confirmed to food-borne botulism. The mean annual incidence per 100,000 Iranian Natives was 7.1 cases for male individuals and 3.3 cases for female individuals. All botulism events were confirmed to be foodborne. The most commonly implicated food was home-prepared traditional processed fish product, followed by the consumption of commercially canned products and non-pasteurized dairy products. Forty-eight (19%) fatal botulism were reported which, the case-fatality rate declined from 4.5% to 0.7% during the study period.

CONCLUSION

Laboratory-based diagnosis of botulism is an imperative procedure to elucidate cases, particularly food-borne botulism, to identify toxins in food and confirm clinical diagnosis, helping sanitary control measures. In addition, educational materials related to botulism prevention should be disseminated to different communities.

Special Delivery: Potential Mechanisms of Botulinum Neurotoxin Uptake and Trafficking within Motor Nerve Terminals

Botulinum neurotoxins (BoNTs) are highly potent, neuroparalytic protein toxins that block the release of acetylcholine from motor neurons and autonomic synapses. The unparalleled toxicity of BoNTs results from the highly specific and localized cleavage of presynaptic proteins required for nerve transmission. Currently, the only pharmacotherapy for botulism is prophylaxis with antitoxin, which becomes progressively less effective as symptoms develop. Treatment for symptomatic botulism is limited to supportive care and artificial ventilation until respiratory function spontaneously recovers, which can take weeks or longer. Mechanistic insights into intracellular toxin behavior have progressed significantly since it was shown that toxins exploit synaptic endocytosis for entry into the nerve terminal, but fundamental questions about host-toxin interactions remain unanswered. Chief among these are mechanisms by which BoNT is internalized into neurons and trafficked to sites of molecular toxicity. Elucidating how receptor-bound toxin is internalized and conditions under which the toxin light chain engages with target SNARE proteins is critical for understanding the dynamics of intoxication and identifying novel therapeutics. Here, we discuss the implications of newly discovered modes of synaptic vesicle recycling on BoNT uptake and intraneuronal trafficking.

Botulism outbreak after the consumption of vegetarian pâté in the south of Viet Nam

Botulism is a potentially life-threatening disease caused by toxins produced by Clostridium botulinum. Here we reported a case series of six patients who presented with botulism following ingestion of commercially made pâté. The key features of presentation were acute onset of bilateral cranial nerve palsies and symmetrical descending weakness in the absence of fever resulting in the need for mechanical ventilation in all six patients. The clinical diagnosis of botulism was confirmed through the identification of C. botulinum from the suspected food source.  Given that botulinum antitoxin was not available in Vietnam at the time, and their severe status, all patients received a trial of plasma exchange therapy, but no clear benefit was seen. Due to its rarity, diagnosing botulism is a challenge, demanding high clinical suspicion. Successful outcomes depend upon early recognition and rapid initiation of specific treatment with botulinum antitoxin. There is a need to improve global access to antitoxin.  These cases, the first in Viet Nam, serve as a reminder of the need to maintain the highest possible food hygiene and preservation practices.

A Quantum Dot Nanobiosensor for Rapid Detection of Botulinum Neurotoxin Serotype E

Botulinum neurotoxins (BoNTs) are potent toxins produced by Clostridium bacteria that are responsible for the illness botulism and are listed as bioterrorism agents. BoNT serotype E (BoNT/E) is one of four BoNT serotypes that cause human botulism and is the second most frequent cause of foodborne botulism. Rapid detection and discrimination of BoNT serotypes implicated in human disease are critical for ensuring timely treatment of patients and identifying sources of toxins, but there have been few reported detection methods for BoNT/E and even fewer methods usable for BoNT serotyping. We report a nanobiosensor based on Förster resonance energy transfer (FRET) between semiconductor nanocrystals (quantum dots, QDs) and dark quencher-labeled peptide probes to detect biologically active BoNT/E in aqueous media. The peptide probes contain a specific cleavage site for active BoNT/E. QD photoluminescence, which changes intensity due to FRET when the peptide probe is cleaved, was used to indicate toxin presence and quantity. The detection of a BoNT/E light chain (LcE) and holotoxin was observed within 3 h. The limits of detection were 0.02 and 2 ng/mL for LcE and holotoxin, respectively. The nanobiosensor shows good specificity toward the target in tests with nontarget BoNT serotypes. The high sensitivity, simple operation, short detection time, and ability to be used in parallel with probes developed for other BoNT serotypes indicate that the nanobiosensor will be useful for rapid BoNT/E detection and serotype discrimination in food analysis.

Symptomatic treatment of botulism with a clinically approved small molecule

Botulinum neurotoxins (BoNTs) are potent neuroparalytic toxins that cause mortality through respiratory paralysis. The approved medical countermeasure for BoNT poisoning is infusion of antitoxin immunoglobulins. However, antitoxins have poor therapeutic efficacy in symptomatic patients; thus, there is an urgent need for treatments that reduce the need for artificial ventilation. We report that the US Food and Drug Administration-approved potassium channel blocker 3,4-diaminopyridine (3,4-DAP) reverses respiratory depression and neuromuscular weakness in murine models of acute and chronic botulism. In ex vivo studies, 3,4-DAP restored end-plate potentials and twitch contractions of diaphragms isolated from mice at terminal stages of BoNT serotype A (BoNT/A) botulism. In vivo, human-equivalent doses of 3,4-DAP reversed signs of severe respiratory depression and restored mobility in BoNT/A-intoxicated mice at terminal stages of respiratory collapse. Multiple-dosing administration of 3,4-DAP improved respiration and extended survival at up to 5 LD50 BoNT/A. Finally, 3,4-DAP reduced gastrocnemius muscle paralysis and reversed respiratory depression in sublethal models of serotype A-, B-, and E-induced botulism. These findings make a compelling argument for repurposing 3,4-DAP to symptomatically treat symptoms of muscle paralysis caused by botulism, independent of serotype. Furthermore, they suggest that 3,4-DAP is effective for a range of botulism symptoms at clinically relevant time points.

Pediatric Botulism and Use of Equine Botulinum Antitoxin in Children: A Systematic Review

Background

Botulism manifests with cranial nerve palsies and flaccid paralysis in children and adults. Botulism must be rapidly identified and treated; however, clinical presentation and treatment outcomes of noninfant botulism in children are not well described.

Methods

We searched 12 databases for peer-reviewed and non-peer-reviewed reports with primary data on botulism in children (persons <18 years of age) or botulinum antitoxin administration to children. Reports underwent title and abstract screening and full text review. For each case, patient demographic, clinical, and outcome data were abstracted.

Results

Of 7065 reports identified, 184 met inclusion criteria and described 360 pediatric botulism cases (79% confirmed, 21% probable) that occurred during 1929-2015 in 34 countries. Fifty-three percent were male; age ranged from 4 months to 17 years (median, 10 years). The most commonly reported signs and symptoms were dysphagia (53%), dysarthria (39%), and generalized weakness (37%). Inpatient length of stay ranged from 1 to 425 days (median, 24 days); 14% of cases required intensive care unit admission; 25% reported mechanical ventilation. Eighty-three (23%) children died. Median interval from illness onset to death was 1 day (range, 0-260 days). Among patients who received antitoxin (n = 193), 23 (12%) reported an adverse event, including rash, fever, serum sickness, and anaphylaxis. Relative risk of death among patients treated with antitoxin compared with patients not treated with antitoxin was 0.24 (95% confidence interval, .14-.40; P < .0001).

Conclusions

Dysphagia and dysarthria were the most commonly reported cranial nerve symptoms in children with botulism; generalized weakness was described more than paralysis. Children who received antitoxin had better survival; serious adverse events were rare. Most deaths occurred early in the clinical course; therefore, botulism in children should be identified and treated rapidly.

The Epidemiology of Foodborne Botulism Outbreaks: A Systematic Review

Background

We performed a systematic review of foodborne botulism outbreaks to describe their clinical aspects and descriptive epidemiology in order to inform public health response strategies.

Methods

We searched seven databases for reports of foodborne botulism outbreaks published in English from database inception to May 2015. We summarized descriptive characteristics and analyzed differences in exposure and toxin types by geographic region. We performed logistic regression to assess correlations between exposure source, implicated food, and outbreak size.

Results

There were 197 outbreaks reported between 1920 and 2014. The median number of cases per outbreak was 3 (range 2-97). The majority of reported outbreaks (109; 55%) occurred in the United States. Toxin types A, B, E, and F were identified as the causative agent in 34%, 16%, 17%, and 1% of outbreaks, respectively. The median duration between exposure and symptom onset was approximately 1 day. The mean percentage of cases requiring mechanical ventilation per outbreak was 34%. Seventy percent of all outbreaks and 77% of small outbreaks (≤11 cases) originated from point source exposures, while commercial foods were significantly (odds ratio, 6.9; 95% confidence interval, 2.2-21.1) associated with large outbreaks (≥12 cases).

Conclusions

Toxin type A accounted for half of outbreaks, and these outbreaks had a higher proportion of patient ventilatory failure. Most outbreaks were due to point source exposures, while outbreaks due to commercial food were larger. For effective responses to foodborne botulism outbreaks, these findings demonstrate the need for timely outbreak investigation and hospital surge capacity.

Clinical Criteria to Trigger Suspicion for Botulism: An Evidence-Based Tool to Facilitate Timely Recognition of Suspected Cases During Sporadic Events and Outbreaks

Effective treatment for botulism requires early clinical recognition. Diagnosis of botulism, including during outbreaks, can be challenging. We assessed combinations of signs and symptoms among confirmed cases and identified sensitive clinical criteria to trigger suspicion. We produced a tool that may facilitate rapid identification of sporadic and outbreak-associated cases.

Clinical Characteristics and Ancillary Test Results Among Patients With Botulism-United States, 2002-2015

Background

Botulism is classically described as a bilateral, symmetric, descending flaccid paralysis in an afebrile and alert patient without sensory findings. We describe the reported spectrum of clinical findings among persons >12 months of age in the United States during 2002-2015.

Methods

The Centers for Disease Control and Prevention collects clinical findings reported by physicians treating suspected cases of botulism nationwide. We analyzed symptoms and signs, and neuroimaging and cerebrospinal fluid (CSF) results. A case was defined as illness compatible with botulism with laboratory confirmation or epidemiologic link to a confirmed case, and presence or absence of at least 1 sign or symptom recorded. Physicians' differential diagnoses were evaluated.

Results

Clinical information was evaluated for 332 botulism cases; data quality and completeness were variable. Most had no fever (99%), descending paralysis (93%), no mental status change (91%), at least 1 ocular weakness finding (84%), and neuroimaging without acute changes (82%). Some had paresthesias (17%), elevated CSF protein level (13%), and other features sometimes considered indicative of alternative diagnoses. Five of 71 (7%) cases with sufficient information were reported to have atypical findings (eg, at least 1 cranial nerve finding that was unilateral or ascending paralysis). Illnesses on the physician differential included Guillain-Barré syndrome (99 cases) and myasthenia gravis (76 cases) and, rarely, gastrointestinal-related illness (5 cases), multiple sclerosis (3 cases), sepsis (3 cases), and Lyme disease (2 cases).

Conclusions

Our analysis illustrates that classic symptoms and signs were common among patients with botulism but that features considered atypical were reported by some physicians. Diagnosis can be challenging, as illustrated by the broad range of illnesses on physician differentials.

Foodborne Botulism: Neglected Diagnosis

Botulism is rare neuroparalytic disease caused by botulinum toxin, one of the most toxic substances known. Foodborne botulism is caused by consumption of foods contaminated with botulinum toxin. The clinical manifestations are flaccid, symmetrical, descending paralysis affecting cranial and peripheral nerves. The only specific treatment is botulinum antitoxin. We report the case of a 37-year-old man with gastrointestinal manifestations and posterior cranial nerve palsy who was diagnosed with botulism infection. Clinicians should be aware of rare causes of infection and determine the aetiology of symptoms.

LEARNING POINTS

Botulism remains a diagnostic challenge.Misdiagnosis of early cases suggests sporadic cases are overlooked.Timely clinical diagnosis is critical for treatment decisions as botulinum antitoxin cannot reverse existing paralysis.

Wound Botulism Outbreak Among Persons Who Use Black Tar Heroin - San Diego County, California, 2017-2018

During September 29-October 6, 2017, the County of San Diego Public Health Services (COSD) was notified of two patients with suspected wound botulism and a history of using black tar heroin. On October 9, COSD, which had reported an average of one wound botulism case per year during 2001-2016, sent a health alert through the California Health Alert Network, notifying Southern California providers of these two patients, including their signs and symptoms and black tar heroin exposure. In collaboration with the California Department of Public Health, COSD conducted an investigation to identify additional cases, determine risk factors for illness, estimate cost of medical care, and develop recommendations to prevent further illness. By April 18, 2018, nine (eight confirmed and one probable) patients with wound botulism were identified, all of whom were hospitalized; one of the nine died. All nine were persons who inject drugs; seven specifically reported using black tar heroin and six practiced subcutaneous injection known as skin popping. Clinically compatible signs and symptoms included muscle weakness, difficulty swallowing, blurred vision, drooping eyelids, slurred speech, difficulty breathing, loss of facial expression, or descending paralysis. All patients were treated with heptavalent botulism antitoxin (BAT). Wound botulism is likely underrecognized because of its rarity and the overlapping signs and symptoms with opioid intoxication, overdose, and other neurologic syndromes including Guillain-Barré syndrome, the Miller Fisher variant of Guillain-Barré syndrome, and myasthenia gravis. Prompt diagnosis, administration of BAT, and provision of supportive care can help stop the progression of paralysis and be lifesaving.

Studying the differential efficacy of postsymptom antitoxin treatment in type A versus type B botulism using a rabbit spirometry model

Botulinum neurotoxin (BoNT) serotypes A, B and E are responsible for most cases of human botulism. The only approved therapy for botulism is antitoxin treatment administered to patients after symptom onset. However, a recent meta-analysis of antitoxin efficacy in human botulism cases over the past century concluded that a statistically significant reduction in mortality is associated with the use of type E and type A antitoxin, but not with type B antitoxin. Animal models could be highly valuable in studying postsymptom antitoxin efficacy (PSAE). However, the few attempts to evaluate PSAE in animals relied on subjective observations and showed ∼50% protection. Recently, we developed a novel spirometry model for the quantitative evaluation of PSAE in rabbits and used it to demonstrate full protection against BoNT/E. In the current study, a comparative evaluation of PSAE in botulism types A and B was conducted using this quantitative respiratory model. A lethal dose of each toxin induced a comparable course of disease both in terms of time to symptoms (TTS, 41.9±1.3 and 40.6±1.1 h, respectively) and of time to death (TTD, 71.3±3.1 and 66.3±1.7 h, respectively). However, in accordance with the differential serotypic PSAE observed in humans, postsymptom antitoxin treatment was fully effective only in BoNT/A-intoxicated rabbits. This serotypic divergence was reflected by a positive and statistically significant correlation between TTS and TTD in BoNT/A-intoxicated rabbits (r=0.91, P=0.0006), but not in those intoxicated with BoNT/B (r=0.06, P=0.88). The rabbit spirometry system might be useful in the evaluation toolkit of botulism therapeutics, including those under development and intended to act when antitoxin is no longer effective.

Summary: Here, we used a quantitative rabbit respiratory model to study the human-related, differential antitoxin efficacy observed in type A and type B botulism.