Multistate Outbreak Research Articles

An Update on Highly Pathogenic Avian Influenza A(H5N1) Virus, Clade 2.3.4.4b.

Since the resurgence of highly pathogenic avian influenza (HPAI) A(H5N1) virus, clade 2.3.4.4b, during 2021, these viruses have spread widely among birds worldwide, causing poultry outbreaks and infections of a wide range of terrestrial and marine mammal species. During 2024, HPAI A(H5N1) virus, clade 2.3.4.4b, was detected in dairy cattle for the first time and caused an ongoing multistate outbreak, with high levels of virus documented in raw cow milk. Human infections with clade 2.3.4.4b viruses from exposures to infected poultry or dairy cattle have resulted in a wide spectrum of illness severity, from conjunctivitis or mild respiratory illness to severe and fatal pneumonia in different countries. Vigilance, and stronger global virologic surveillance among birds, poultry, terrestrial and marine mammals, and humans, with virus characterization and rapid data sharing, is needed to inform the threat of clade 2.3.4.4b viruses, as they continue to evolve, to public health.

An Outbreak Investigation of Salmonella Weltevreden Illnesses in the United States Linked to Frozen Precooked Shrimp Imported from India – 2021

In 2021, the U.S. Food and Drug Administration (FDA), Centers for Disease Control and Prevention (CDC), and state partners investigated a multistate sample-initiated retrospective outbreak investigation (SIROI) consisting of a cluster of nine Salmonella Weltevreden illnesses associated with frozen, precooked shrimp imported from India. Import surveillance testing identified Salmonella Weltevreden recovered from a cooked shrimp sample from Supplier B. In total, nine patients with clinical isolates highly related via whole genome sequencing were reported in four states with illness onset dates between February 26 and July 17, 2021. Epidemiologic data were gathered by state partners for seven patients, who all reported exposure to shrimp. Five patients reported consuming shrimp cocktail from the same retailer. A traceback investigation for five of the six patients converged on Supplier B. This evidence demonstrated that the outbreak of Salmonella Weltevreden illnesses was caused by the consumption of cooked, ready-to-eat shrimp manufactured by Supplier B. At the time of the investigation, outbreak and recall information was shared with Indian competent authorities. In March 2022, a follow-up inspection of Supplier B’s facility in India was conducted, and insanitary conditions and practices were observed. This outbreak investigation highlighted the importance of multidisciplinary national and international public health partnerships. The lessons learned from this investigation should continue to inform investigational activities and food safety guidance for the industry.

Comparison of Extraction Methods for the Detection of Avian Influenza Virus RNA in Cattle Milk.

Since early 2024, a multistate outbreak of highly pathogenic avian influenza H5N1 has been affecting dairy cattle in the USA. The influenza viral RNA concentrations in milk make it an ideal matrix for surveillance purposes. However, viral RNA detection in multi-component fluids such as milk can be complex, and optimization of influenza detection methods is thus required. Raw bulk tank milk and mastitis milk samples were artificially contaminated with an avian influenza strain and subjected to five extraction methods. HCoV-229E and synthetic RNA were included as exogenous internal process controls. Given the high viral load usually observed in individual raw milk samples, four out of five tested methods would enable influenza detection in milk with normal texture, over a time window of at least 2 weeks post-onset of clinical signs. Nevertheless, sample dilution 1:3 in molecular transport medium prior to RNA extraction provided the best results for dilution of inhibitory substances and a good recovery rate of influenza RNA, that reached 12.5 ± 1.2% and 10.4 ± 3.8% in two independent experiments in bulk milk and 11.2 ± 3.6% and 10.0 ± 2.9% on two cohorts of mastitis milk samples. We have also shown compatibility of an influenza RT-qPCR system with synthetic RNA detection for simultaneous validation of the RNA extraction and RT-qPCR processes.

Vesicular Stomatitis Virus Detected in Biting Midges and Black Flies during the 2023 Outbreak in Southern California.

Vesicular stomatitis (VS) is a viral disease that affects horses, cattle, and swine that is transmitted by direct contact and hematophagous insects. In 2023, a multi-state outbreak of vesicular stomatitis New Jersey virus (VSNJV) occurred in California, Nevada, and Texas, infecting horses, cattle, and rhinoceros. To identify possible insect vectors, we conducted insect surveillance at various locations in San Diego County, CA, including at a wildlife park. CO2 baited traps set from mid-May to mid-August 2023 collected 2357 Culicoides biting midges and 1215 Simulium black flies, which are insect genera implicated in VSNJV transmission. Insects were pooled by species, location, and date, then tested for viral RNA. Nine RNA-positive pools of Culicoides spp. and sixteen RNA-positive pools of Simulium spp were detected. Infectious virus was detected by cytopathic effect in 96% of the RNA-positive pools. This is the first report of VSNJV in wild-caught C. bergi, C. freeborni, C. occidentalis, S. argus, S. hippovorum, and S. tescorum. The vector competency of these species for VSNJV has yet to be determined but warrants examination. Active vector surveillance and testing during disease outbreaks increases our understanding of the ecology and epidemiology of VS and informs vector control efforts.

The American Association of Tissue Banks tissue donor screening for Mycobacterium tuberculosis—Recommended criteria and literature review

AbstractAfter two multistate outbreaks of allograft tissue‐transmitted tuberculosis (TB) due to viable bone, evidence‐based donor screening criteria were developed to decrease the risk of transmission to recipients. Exclusionary criteria, commentary, and references supporting the criteria are provided, based on literature search and expert opinion. Both exposure and reactivation risk factors were considered, either for absolute exclusion or for exclusion in combination with multiple risk factors. A criteria subset was devised for tissues containing viable cells. Risk factors for consideration included exposure (e.g., geographic birth and residence, travel, homelessness, incarceration, healthcare, and workplace) and reactivation (e.g., kidney disease, liver disease, history of transplantation, immunosuppressive medications, and age). Additional donor considerations include the possibility of sepsis and chronic illness. Donor screening criteria represent minimal criteria for exclusion and do not completely exclude all possible donor TB risks. Additional measures to reduce transmission risk, such as donor and product testing, are discussed but not included in the recommendations. Careful donor evaluation is critical to tissue safety.

Multistate outbreaks of salmonellosis linked to contact with backyard poultry-United States, 2015-2022.

Contact with backyard poultry (i.e., privately-owned, non-commercial poultry) was first associated with a multistate outbreak of salmonellosis in 1955. In recent years, backyard poultry-associated salmonellosis outbreaks have caused more illnesses in the United States than salmonellosis outbreaks linked to any other type of animal. Here, we describe the epidemiology of outbreaks from 2015-2022 to inform prevention efforts. During 2015-2022, there were 88 multistate backyard poultry-associated salmonellosis outbreaks and 7866 outbreak-associated illnesses caused by 21 different Salmonella serotypes. Salmonella Enteritidis accounted for the most outbreaks (n = 21) and illnesses (n = 2400) of any serotype. Twenty-four percent (1840/7727) of patients with available information were <5 years of age. In total, 30% (1710/5644) of patients were hospitalized, and nine deaths were attributed to Salmonella infection. Throughout this period, patients reported behaviours that have a higher risk of Salmonella transmission, including kissing or snuggling poultry or allowing poultry inside their home. Despite ongoing efforts to reduce the burden of salmonellosis associated with backyard poultry, outbreak-associated illnesses have nearly tripled and hospitalizations more than quadrupled compared with those in 1990-2014. Because this public health problem is largely preventable, government officials, human and veterinary healthcare providers, hatcheries, and retailers might improve the prevention of illnesses by widely disseminating health and safety recommendations to the public and by continuing to develop and implement prevention measures to reduce zoonotic transmission of Salmonella by backyard poultry.

Extensively Drug-Resistant Pseudomonas aeruginosa Outbreak Associated With Artificial Tears.

Carbapenemase-producing, carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA) are extensively drug-resistant bacteria. We investigated the source of a multistate CP-CRPA outbreak. Cases were defined as a US patient's first isolation of P. aeruginosa sequence type 1203 with carbapenemase gene blaVIM-80 and cephalosporinase gene blaGES-9 from any specimen source collected and reported to the Centers for Disease Control and Prevention during 1 January 2022-15 May 2023. We conducted a 1:1 matched case-control study at the post-acute care facility with the most cases, assessed exposures associated with case status for all case-patients, and tested products for bacterial contamination. We identified 81 case-patients from 18 states, 27 of whom were identified through surveillance cultures. Four (7%) of 54 case-patients with clinical cultures died within 30 days of culture collection, and 4 (22%) of 18 with eye infections underwent enucleation. In the case-control study, case-patients had increased odds of receiving artificial tears versus controls (crude matched OR, 5.0; 95% CI, 1.1-22.8). Overall, artificial tears use was reported by 61 (87%) of 70 case-patients with information; 43 (77%) of 56 case-patients with brand information reported use of Brand A, an imported, preservative-free, over-the-counter (OTC) product. Bacteria isolated from opened and unopened bottles of Brand A were genetically related to patient isolates. Food and Drug Administration inspection of the manufacturing plant identified likely sources of contamination. A manufactured medical product serving as the vehicle for carbapenemase-producing organisms is unprecedented in the United States. The clinical impacts from this outbreak underscore the need for improved requirements for US OTC product importers.

Multistate outbreak of Salmonella Oranienburg infections linked to bulb onions imported from Mexico – United States, 2021

In 2021, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and state and local health and regulatory partners investigated an outbreak of Salmonella enterica serovar Oranienburg infections linked to bulb onions from Mexico, resulting in 1040 illnesses and 260 hospitalizations across 39 states, the District of Columbia, and Puerto Rico. The Kansas Department of Agriculture recovered the outbreak strain of Salmonella Oranienburg from a sample of condiment collected from an ill person's home. The condiment was made with cilantro, lime, and onions, but, at the time of collection, there were no onions remaining in it. FDA conducted traceback investigations for white, yellow, and red bulb onions, cilantro, limes, tomatoes, and jalapeño peppers. Growers in the state of Chihuahua, Mexico, were identified as supplying the implicated onions that could account for exposure to onions for all illnesses included in the traceback investigation, but investigators could not determine a single source or route of contamination. FDA collected product and environmental samples across the domestic supply chain but did not recover the outbreak strain of Salmonella. Binational collaboration and information sharing supported Mexican authorities in collecting environmental samples from two packing plants and onion, water, and environmental samples from 15 farms and firms in Chihuahua, Mexico identified through FDA's traceback investigation, but did not recover the outbreak strain.. Distributors of the implicated onions issued voluntary recalls of red, yellow, and white whole, fresh onions imported from the state of Chihuahua, Mexico. This outbreak showcased how investigators overcame significant traceback and epidemiologic challenges, the need for strengthening the ongoing collaboration between U.S. and Mexican authorities and highlighted the need for identifying practices across the supply chain that can help improve the safety of onions.

The financial impact of foodborne illness outbreaks at restaurants: Chipotle Mexican Grill

AbstractAs demand for food away from home increases, outbreaks at restaurants become an important source of food‐related illness. In the United States, over 60% of foodborne illness outbreaks occur at restaurants and 97% of outbreaks are limited to a single state. Despite this, we currently know little about restaurant outbreaks and in particular, single‐state outbreaks are not well understood. We use Chipotle Mexican Grill's eight outbreaks (2015–2018) to evaluate the media and stock market responses to both single and multistate outbreaks. Using news and stock market data, we provide evidence that multistate outbreaks brought swift stock price declines and single‐state outbreaks' impact depended on their timing, rather than their severity. Before Chipotle's more well‐known, multistate outbreaks, the firm's single‐state outbreaks brought little reporting and no financial losses, whereas after the multistate food safety events, single‐state events resulted in national media coverage and large financial impacts. Our findings are consistent with the literature on food scares that can result in chronic low‐level anxiety, which can bring about a large resurgence of concern for smaller outbreaks. The lessons learned from Chipotle's case underscore the importance of investment in outbreak prevention. [G14 (Information and Market Efficiency, Event Studies, Insider Trading)].

Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018.

Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates.

Focus Groups Exploring U.S. Adults’ Knowledge, Attitudes, and Practices Related to Irradiation as a Food Safety Intervention, 2021

Food irradiation has been studied comprehensively and has been determined to be a safe and effective process for improving food safety. Despite this potential public health impact and current use in developed countries, the technology is not commonly used in the United States, with consumer acceptance often cited as a barrier. Given changes in consumer food-purchasing trends, advancements in irradiation technology, and an increase in multistate foodborne outbreaks, it is an opportune time to revisit consumer acceptance and factors that influence the purchase of irradiated food. We conducted seven focus groups to assess knowledge, attitudes, and practices regarding irradiation as a food safety intervention. Meetings were virtual, lasted 90 min, and were held March 15–18, 2021. Participants were stratified into three groups using quota sampling: adults aged 18–64 years, parents of children aged 0–4 years, and adults aged 65 years and older. Consistent with past research, consumers were unaware of what food irradiation is. Facilitators for purchasing irradiated foods included protection from foodborne illness, reduced risk from certain foods, and support from public health agencies. Barriers included lack of knowledge, safety concerns, price, packaging, and a distrust of food technology. The results from these focus groups can inform public messaging and foodborne illness prevention strategies.

Human Salmonellosis Outbreak Linked to Salmonella Typhimurium Epidemic in Wild Songbirds, United States, 2020-2021.

Salmonella infection causes epidemic death in wild songbirds, with potential to spread to humans. In February 2021, public health officials in Oregon and Washington, USA, isolated a strain of Salmonella enterica serovar Typhimurium from humans and a wild songbird. Investigation by public health partners ultimately identified 30 illnesses in 12 states linked to an epidemic of Salmonella Typhimurium in songbirds. We report a multistate outbreak of human salmonellosis associated with songbirds, resulting from direct handling of sick and dead birds or indirect contact with contaminated birdfeeders. Companion animals might have contributed to the spread of Salmonella between songbirds and patients; the outbreak strain was detected in 1 ill dog, and a cat became ill after contact with a wild bird. This outbreak highlights a One Health issue where actions like regular cleaning of birdfeeders might reduce the health risk to wildlife, companion animals, and humans.

Genomic and phenotypic comparison of two variants of multidrug-resistant Salmonella enterica serovar Heidelberg isolated during the 2015-2017 multi-state outbreak in cattle.

Salmonella enterica subspecies enterica serovar Heidelberg (Salmonella Heidelberg) has caused several multistate foodborne outbreaks in the United States, largely associated with the consumption of poultry. However, a 2015-2017 multidrug-resistant (MDR) Salmonella Heidelberg outbreak was linked to contact with dairy beef calves. Traceback investigations revealed calves infected with outbreak strains of Salmonella Heidelberg exhibited symptoms of disease frequently followed by death from septicemia. To investigate virulence characteristics of Salmonella Heidelberg as a pathogen in bovine, two variants with distinct pulse-field gel electrophoresis (PFGE) patterns that differed in morbidity and mortality during the multistate outbreak were genotypically and phenotypically characterized and compared. Strain SX 245 with PFGE pattern JF6X01.0523 was identified as a dominant and highly pathogenic variant causing high morbidity and mortality in affected calves, whereas strain SX 244 with PFGE pattern JF6X01.0590 was classified as a low pathogenic variant causing less morbidity and mortality. Comparison of whole-genome sequences determined that SX 245 lacked ~200 genes present in SX 244, including genes associated with the IncI1 plasmid and phages; SX 244 lacked eight genes present in SX 245 including a second YdiV Anti-FlhC(2)FlhD(4) factor, a lysin motif domain containing protein, and a pentapeptide repeat protein. RNA-sequencing revealed fimbriae-related, flagella-related, and chemotaxis genes had increased expression in SX 245 compared to SX 244. Furthermore, SX 245 displayed higher invasion of human and bovine epithelial cells than SX 244. These data suggest that the presence and up-regulation of genes involved in type 1 fimbriae production, flagellar regulation and biogenesis, and chemotaxis may play a role in the increased pathogenicity and host range expansion of the Salmonella Heidelberg isolates involved in the bovine-related outbreak.

Multistate outbreak of turtle-associated salmonellosis highlights ongoing challenges with the illegal sale and distribution of small turtles.

The sale and distribution of small turtles (shell length <4 inches) as pets has been banned in the United States since 1975 because of the risk of Salmonella transmission, especially to children. Despite this 48-year-old ban, salmonellosis outbreaks continue to be linked to contact with small turtles. During investigations of turtle-associated outbreaks, information regarding the turtle farm of origin is difficult to obtain because turtles are commonly sold by transient vendors. During 2020-2021, public health officials investigated a multistate illness outbreak caused by Salmonella enterica serotype Typhimurium linked to pet small turtles. Cases were defined as a laboratory-confirmed Salmonella Typhimurium infection highly related (within 0-6 allele differences) to the outbreak strain based on whole-genome sequencing analysis by core-genome multilocus sequence typing with illness onset occurring during 27 August 2020-14 May 2021. Forty-three patients were identified from 12 states; of these, 35% (15/43) were children <5 years old. Among patients with available information, 37% (14/38) were hospitalized, and one death was reported. Seventy-four percent (25/34) of patients reported turtle exposure in the week before illness onset, and 84% (16/19) specified exposure to small turtles. The outbreak strain was isolated from samples collected from a Pennsylvania patient's small turtle tank. Two patients reported purchasing their small turtles from pet stores. Salmonella Braenderup was isolated from samples collected from small turtles and their habitat at one of these stores; however, at that time, this strain was not associated with any human illnesses. This investigation was notable because of the documented sale of small turtles from several pet stores combined with the identification of a single small turtle supplier to these pet stores. The high proportion of children involved in this outbreak highlights the continued need to educate the pet industry as well as parents and caregivers about the risk of turtle-associated salmonellosis especially in children. Understanding and addressing the persisting challenges related to the illegal sale and distribution of small turtles could reduce the burden of turtle-associated salmonellosis.

Update on Outbreak of Fungal Meningitis Among US Residents Who Received Epidural Anesthesia at Two Clinics in Matamoros, Mexico.

Public health officials are responding to an outbreak of fungal meningitis among patients who received procedures under epidural anesthesia at 2 clinics (River Side Surgical Center and Clinica K-3) in Matamoros, Mexico, during 1 January to 13 May 2023. This report describes outbreak epidemiology and outlines interim diagnostic and treatment recommendations. Interim recommendations for diagnosis and management were developed by the Mycoses Study Group Research Education and Consortium (MSGERC) based on the clinical experience of clinicians caring for patients during the current outbreak or during previous outbreaks of healthcare-associated fungal meningitis in Durango, Mexico, and the United States. As of 7 July 2023, the situation has evolved into a multistate and multinational fungal meningitis outbreak. A total of 185 residents in 22 US states and jurisdictions have been identified who might be at risk of fungal meningitis because they received epidural anesthesia at the clinics of interest in 2023. Among these patients, 11 suspected, 10 probable, and 10 confirmed US cases have been diagnosed, with severe vascular complications and 8 deaths occurring. Fusarium solani species complex has been identified as the causative agent, with antifungal susceptibility testing of a single isolate demonstrating poor in vitro activity for most available antifungals. Currently, triple therapy with intravenous voriconazole, liposomal amphotericin B, and fosmanogepix is recommended. Efforts to understand the source of this outbreak and optimal treatment approaches are ongoing, but infectious diseases physicians should be aware of available treatment recommendations. New information will be available on the Centers for Disease Control and Prevention's (CDC's) website.

Artificial tears: Promising treatment or silent threat to public health?

Dry Eye Disease (DED) is a multifactorial chronic inflammatory condition of the corneal surface, attributed to insufficient or low-quality production of tears, accounting for 5-50% of the cases globally. Artificial tears are the first line of treatment as they reduce ocular surface tension, and improve film stability and optical quality. EzriCare Artificial Tears are preservative-free, multi-dose, readily accessible eye drops containing carboxymethylcellulose sodium solution (10 mg in 1 ml) aiming for relief against DED. This article discusses the public health challenges faced by the use of EzriCare Artificial Tears and emphasizes the need for alternative therapies for the effective management of DED. We searched for articles documenting the incidence of the current multi-drug resistant P. aeruginosa strain outbreak caused by the use of preservative-free artificial tears and the challenges faced through the use of artificial tears on PubMed, and Google Scholar. EzriCare and other preservative-free artificial tears have been reported to pose a serious public health risk as they have been found to be the commonly used product among the people infected with the current multi-state outbreak of the multi-drug resistant P. aeruginosa strain. The current multi-state outbreak of the multi-drug resistant P. aeruginosa strain has raised concerns about the safe use of other artificial products. It is high time that further trials should be conducted on other alternative strategies and evaluate the safety and efficacy of nanotechnology in the treatment of dry eye disease.

CASE REPORT: Multidrug-resistant Pseudomonas keratitis and sequential endophthalmitis treated with chlorhexidine and piperacillin-tazobactam

Purpose To report the clinical course and treatment strategies employed in management of a case of multidrug-resistant Pseudomonas aeruginosa keratitis progressing to endophthalmitis. The drug-resistant strain was later traced to use of contaminated EzriCare Artificial Tears in a multi-state cluster outbreak. Observations A 57-year-old male patient with a history of Descemet stripping automated endothelial keratoplasty was referred for a culture-positive Pseudomonas corneal ulcer in the right eye that had been treated with several weeks of topical moxifloxacin, fortified vancomycin and tobramycin, and intravitreal injections for endophthalmitis. His cornea was cultured off of antibiotics and grew only rare Propionibacterium acnes. Topical antibiotics and steroids were reduced, but his condition rapidly deteriorated with leading to corneal melt, perforation, and endophthalmitis. Repeat corneal cultures and sensitivity analyses revealed growth of a strain of Pseudomonas aeruginosa that was resistant to fluoroquinolones, aminoglycosides, cephalosporins, monobactams, and carbapenems, and only intermediate susceptibility to piperacillin-tazobactam. The patient underwent a therapeutic penetrating keratoplasty and was subsequently initiated on an intensive regimen of topical chlorhexidine and polymyxin-B/trimethoprim. He also underwent a pars plana vitrectomy with anterior chamber washout, followed by serial injections of intravitreal piperacillin-tazobactam at a dose of 225 mg/0.1 mL. After 8 weeks of intensive treatment, there was gradual with healing of his ocular surface, regression of his hypopyon and posterior inflammation, and no signs of recurrent infection. A public health investigation ultimately revealed that his infection was one of several cases involved in a multistate cluster outbreak of extensively drug-resistant Pseudomonas ocular infections that were traced to the use of contaminated EzriCare Artificial Tears. Conclusions and Importance Multidrug-resistant keratitis and endophthalmitis caused by multidrug-resistant Pseudomonas keratitis requires consideration of nonconventional antimicrobial agents and experimental therapeutic alternatives. Topical chlorhexidine and intravitreal piperacillin-tazobactam are currently nonconventional therapies in the context of bacterial keratitis and endophthalmitis, but were safe and effective in the management of multidrug-resistant Pseudomonas aeruginosa ocular infection.

Notes from the Field: Multistate Outbreak of Escherichia coli O157:H7 Infections Linked to a National Fast-Food Chain - United States, 2022.

Notes from the Field: Multistate Outbreak of Escherichia coli O157:H7 Infections Linked to a National Fast-Food Chain - United States, 2022.

Investigation of a Multistate Outbreak of Listeria monocytogenes Infections Linked to Frozen Vegetables Produced at Individually Quick-Frozen Vegetable Manufacturing Facilities

In 2016, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and state partners investigated nine Listeria monocytogenes infections linked to frozen vegetables. The investigation began with two environmental L. monocytogenes isolates recovered from Manufacturer A, primarily a processor of frozen onions, that were a match by whole genome sequencing (WGS) to eight clinical isolates and historical onion isolates with limited collection details. Epidemiologic information, product distribution, and laboratory evidence linked suspect food items, including products sourced from Manufacturer B, also a manufacturer of frozen vegetable/fruit products, with an additional illness. The environmental isolates were obtained during investigations at Manufacturers A and B. State and federal partners interviewed ill people, analyzed shopper card data, and collected household and retail samples. Nine ill persons between 2013 and 2016 were reported in four states. Of four ill people with information available, frozen vegetable consumption was reported by three, with shopper cards confirming purchases of Manufacturer B brands. Two identified outbreak strains of L. monocytogenes (Outbreak Strain 1 and Outbreak Strain 2) were a match to environmental isolates from Manufacturer A and/or isolates from frozen vegetables recovered from open and unopened product samples sourced from Manufacturer B; the investigation resulted in extensive voluntary recalls. The close genetic relationship between isolates helped investigators determine the source of the outbreak and take steps to protect public health. This is the first known multistate outbreak of listeriosis in the United States linked to frozen vegetables and highlights the significance of sampling and WGS analyses when there is limited epidemiologic information. Additionally, this investigation emphasizes the need for further research regarding food safety risks associated with frozen foods.

Systematic contact investigation: An essential infection prevention skill to prevent tuberculosis transmission in healthcare settings

A systematic approach to contact investigations has long been a cornerstone of interrupting the transmission of tuberculosis in community settings. This paper describes the implementation of a systematic 10-step contact investigation within an acute care setting during a multistate outbreak of healthcare-associated tuberculosis. A systematic approach to contact investigations might have applicability to the prevention of other communicable infections within healthcare settings.