Power Law for Estimating Underdetection of Foodborne Disease Outbreaks, United States.

We fit a power law distribution to US foodborne disease outbreaks to assess underdetection and underreporting. We predicted that 788 fewer than expected small outbreaks were identified annually during 1998-2017 and 365 fewer during 2018-2019, after whole-genome sequencing was implemented. Power law can help assess effectiveness of public health interventions.

Preliminary Incidence and Trends of Infections Caused by Pathogens Transmitted Commonly Through Food - Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2022.

Each year, infections from major foodborne pathogens are responsible for an estimated 9.4 million illnesses, 56,000 hospitalizations, and 1,350 deaths in the United States (1). To evaluate progress toward prevention of enteric infections in the United States, the Foodborne Diseases Active Surveillance Network (FoodNet) conducts surveillance for laboratory-diagnosed infections caused by eight pathogens transmitted commonly through food at 10 U.S. sites. During 2020-2021, FoodNet detected decreases in many infections that were due to behavioral modifications, public health interventions, and changes in health care-seeking and testing practices during the COVID-19 pandemic. This report presents preliminary estimates of pathogen-specific annual incidences during 2022, compared with average annual incidences during 2016-2018, the reference period for the U.S. Department of Health and Human Services' Healthy People 2030 targets (2). Many pandemic interventions ended by 2022, resulting in a resumption of outbreaks, international travel, and other factors leading to enteric infections. During 2022, annual incidences of illnesses caused by the pathogens Campylobacter, Salmonella, Shigella, and Listeria were similar to average annual incidences during 2016-2018; however, incidences of Shiga toxin-producing Escherichia coli (STEC), Yersinia, Vibrio, and Cyclospora illnesses were higher. Increasing culture-independent diagnostic test (CIDT) usage likely contributed to increased detection by identifying infections that would have remained undetected before widespread CIDT usage. Reducing pathogen contamination during poultry slaughter and processing of leafy greens requires collaboration among food growers and processors, retail stores, restaurants, and regulators.

Risk for Newly Diagnosed Diabetes >30 Days After SARS-CoV-2 Infection Among Persons Aged <18 Years - United States, March 1, 2020-June 28, 2021.

The COVID-19 pandemic has disproportionately affected people with diabetes, who are at increased risk of severe COVID-19.* Increases in the number of type 1 diabetes diagnoses (1,2) and increased frequency and severity of diabetic ketoacidosis (DKA) at the time of diabetes diagnosis (3) have been reported in European pediatric populations during the COVID-19 pandemic. In adults, diabetes might be a long-term consequence of SARS-CoV-2 infection (4-7). To evaluate the risk for any new diabetes diagnosis (type 1, type 2, or other diabetes) >30 days† after acute infection with SARS-CoV-2 (the virus that causes COVID-19), CDC estimated diabetes incidence among patients aged <18 years (patients) with diagnosed COVID-19 from retrospective cohorts constructed using IQVIA health care claims data from March 1, 2020, through February 26, 2021, and compared it with incidence among patients matched by age and sex 1) who did not receive a COVID-19 diagnosis during the pandemic, or 2) who received a prepandemic non-COVID-19 acute respiratory infection (ARI) diagnosis. Analyses were replicated using a second data source (HealthVerity; March 1, 2020-June 28, 2021) that included patients who had any health care encounter possibly related to COVID-19. Among these patients, diabetes incidence was significantly higher among those with COVID-19 than among those 1) without COVID-19 in both databases (IQVIA: hazard ratio [HR] = 2.66, 95% CI = 1.98-3.56; HealthVerity: HR = 1.31, 95% CI = 1.20-1.44) and 2) with non-COVID-19 ARI in the prepandemic period (IQVIA, HR = 2.16, 95% CI = 1.64-2.86). The observed increased risk for diabetes among persons aged <18 years who had COVID-19 highlights the importance of COVID-19 prevention strategies, including vaccination, for all eligible persons in this age group,§ in addition to chronic disease prevention and management. The mechanism of how SARS-CoV-2 might lead to incident diabetes is likely complex and could differ by type 1 and type 2 diabetes. Monitoring for long-term consequences, including signs of new diabetes, following SARS-CoV-2 infection is important in this age group.

Preliminary Incidence and Trends of Infections Caused by Pathogens Transmitted Commonly Through Food - Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2016-2021.

To evaluate progress toward prevention of enteric infections in the United States, the Foodborne Diseases Active Surveillance Network (FoodNet) conducts active population-based surveillance for laboratory-diagnosed infections caused by Campylobacter, Cyclospora, Listeria, Salmonella, Shiga toxin-producing Escherichia coli (STEC), Shigella, Vibrio, and Yersinia at 10 U.S. sites. This report summarizes preliminary 2021 data and describes changes in annual incidence compared with the average annual incidence for 2016-2018, the reference period for the U.S. Department of Health and Human Services' (HHS) Healthy People 2030 goals for some pathogens (1). During 2021, the incidence of infections caused by Salmonella decreased, incidence of infections caused by Cyclospora, Yersinia, and Vibrio increased, and incidence of infections caused by other pathogens did not change. As in 2020, behavioral modifications and public health interventions implemented to control the COVID-19 pandemic might have decreased transmission of enteric infections (2). Other factors (e.g., increased use of telemedicine and continued increase in use of culture-independent diagnostic tests [CIDTs]) might have altered their detection or reporting (2). Much work remains to achieve HHS Healthy People 2030 goals, particularly for Salmonella infections, which are frequently attributed to poultry products and produce, and Campylobacter infections, which are frequently attributed to chicken products (3).

Hypothesis Generation During Foodborne-Illness Outbreak Investigations.

Hypothesis generation is a critical, but challenging, step in a foodborne outbreak investigation. The pathogens that contaminate food have many diverse reservoirs, resulting in seemingly limitless potential vehicles. Identifying a vehicle is particularly challenging for clusters detected through national pathogen-specific surveillance, because cases can be geographically dispersed and lack an obvious epidemiologic link. Moreover, state and local health departments could have limited resources to dedicate to cluster and outbreak investigations. These challenges underscore the importance of hypothesis generation during an outbreak investigation. In this review, we present a framework for hypothesis generation focusing on 3 primary sources of information, typically used in combination: 1) known sources of the pathogen causing illness; 2) person, place, and time characteristics of cases associated with the outbreak (descriptive data); and 3) case exposure assessment. Hypothesis generation can narrow the list of potential food vehicles and focus subsequent epidemiologic, laboratory, environmental, and traceback efforts, ensuring that time and resources are used more efficiently and increasing the likelihood of rapidly and conclusively implicating the contaminated food vehicle.

Turtle-Associated Salmonellosis, United States, 2006-2014.

During 2006-2014, a total of 15 multistate outbreaks of turtle-associated salmonellosis in humans were reported in the United States. Exposure to small pet turtles has long been recognized as a source of human salmonellosis. The risk to public health has persisted and may be increasing. Turtles are a popular reptilian pet among children, and numerous risky behaviors for the zoonotic transmission of Salmonella bacteria to children have been reported in recent outbreaks. Despite a long-standing federal ban against the sale and distribution of turtles <4 in (<10.16 cm) long, these small reptiles can be readily acquired through multiple venues and continue to be the main source of turtle-associated salmonellosis in children. Enhanced efforts are needed to minimize the disease risk associated with small turtle exposure. Prevention will require novel partnerships and a comprehensive One Health approach involving human, animal, and environmental health.

Multistate outbreak of listeriosis associated with cantaloupe.

BACKGROUND: Although new pathogen-vehicle combinations are increasingly being identified in produce-related disease outbreaks, fresh produce is a rarely recognized vehicle for listeriosis. We investigated a nationwide listeriosis outbreak that occurred in the United States during 2011. METHODS: We defined an outbreak-related case as a laboratory-confirmed infection with any of five outbreak-related subtypes of Listeria monocytogenes isolated during the period from August 1 through October 31, 2011. Multistate epidemiologic, trace-back, and environmental investigations were conducted, and outbreak-related cases were compared with sporadic cases reported previously to the Listeria Initiative, an enhanced surveillance system that routinely collects detailed information about U.S. cases of listeriosis. RESULTS: We identified 147 outbreak-related cases in 28 states. The majority of patients (127 of 147, 86%) were 60 years of age or older. Seven infections among pregnant women and newborns and one related miscarriage were reported. Of 145 patients for whom information about hospitalization was available, 143 (99%) were hospitalized. Thirty-three of the 147 patients (22%) died. Patients with outbreak-related illness were significantly more likely to have eaten cantaloupe than were patients 60 years of age or older with sporadic illness (odds ratio, 8.5; 95% confidence interval, 1.3 to ∞). Cantaloupe and environmental samples collected during the investigation yielded isolates matching all five outbreak-related subtypes, confirming that whole cantaloupe produced by a single Colorado farm was the outbreak source. Unsanitary conditions identified in the processing facility operated by the farm probably resulted in contamination of cantaloupes with L. monocytogenes. CONCLUSIONS: Raw produce, including cantaloupe, can serve as a vehicle for listeriosis. This outbreak highlights the importance of preventing produce contamination within farm and processing environments.

Campylobacter fetus infections in humans: exposure and disease.

Campylobacter fetus can cause intestinal illness and, occasionally, severe systemic infections. Infections mainly affect persons at higher risk, including elderly and immunocompromised individuals and those with occupational exposure to infected animals. Outbreaks are infrequent but have provided insight into sources. Source attribution of sporadic cases through case-control interviews has not been reported. The reservoirs for C. fetus are mainly cattle and sheep. Products from these animals are suspected as sources for human infections. Campylobacter fetus is rarely isolated from food, albeit selective isolation methods used in food microbiology are not suited for its detection. We hypothesize that the general population is regularly exposed to C. fetus through foods of animal origin, cross-contaminated foodstuffs, and perhaps other, as yet unidentified, routes. Campylobacter fetus infection should be suspected particularly in patients with nonspecific febrile illness who are immunocompromised or who may have been occupationally exposed to ruminants.

Salmonella typhimurium infections associated with peanut products.

BACKGROUND: Contaminated food ingredients can affect multiple products, each distributed through various channels and consumed in multiple settings. Beginning in November 2008, we investigated a nationwide outbreak of salmonella infections. METHODS: A case was defined as laboratory-confirmed infection with the outbreak strain of Salmonella Typhimurium occurring between September 1, 2008, and April 20, 2009. We conducted two case-control studies, product "trace-back," and environmental investigations. RESULTS: Among 714 case patients identified in 46 states, 166 (23%) were hospitalized and 9 (1%) died. In study 1, illness was associated with eating any peanut butter (matched odds ratio, 2.5; 95% confidence interval [CI], 1.3 to 5.3), peanut butter-containing products (matched odds ratio, 2.2; 95% CI, 1.1 to 4.7), and frozen chicken products (matched odds ratio, 4.6; 95% CI, 1.7 to 14.7). Investigations of focal clusters and single cases associated with nine institutions identified a single institutional brand of peanut butter (here called brand X) distributed to all facilities. In study 2, illness was associated with eating peanut butter outside the home (matched odds ratio, 3.9; 95% CI, 1.6 to 10.0) and two brands of peanut butter crackers (brand A: matched odds ratio, 17.2; 95% CI, 6.9 to 51.5; brand B: matched odds ratio, 3.6; 95% CI, 1.3 to 9.8). Both cracker brands were made from brand X peanut paste. The outbreak strain was isolated from brand X peanut butter, brand A crackers, and 15 other products. A total of 3918 peanut butter-containing products were recalled between January 10 and April 29, 2009. CONCLUSIONS: Contaminated peanut butter and peanut products caused a nationwide salmonellosis outbreak. Ingredient-driven outbreaks are challenging to detect and may lead to widespread contamination of numerous food products.

2008 outbreak of Salmonella Saintpaul infections associated with raw produce.

BACKGROUND: Raw produce is an increasingly recognized vehicle for salmonellosis. We investigated a nationwide outbreak that occurred in the United States in 2008. METHODS: We defined a case as diarrhea in a person with laboratory-confirmed infection with the outbreak strain of Salmonella enterica serotype Saintpaul. Epidemiologic, traceback, and environmental studies were conducted. RESULTS: Among the 1500 case subjects, 21% were hospitalized, and 2 died. In three case-control studies of cases not linked to restaurant clusters, illness was significantly associated with eating raw tomatoes (matched odds ratio, 5.6; 95% confidence interval [CI], 1.6 to 30.3); eating at a Mexican-style restaurant (matched odds ratio, 4.6; 95% CI, 2.1 to ∞) and eating pico de gallo salsa (matched odds ratio, 4.0; 95% CI, 1.5 to 17.8), corn tortillas (matched odds ratio, 2.3; 95% CI, 1.2 to 5.0), or salsa (matched odds ratio, 2.1; 95% CI, 1.1 to 3.9); and having a raw jalapeño pepper in the household (matched odds ratio, 2.9; 95% CI, 1.2 to 7.6). In nine analyses of clusters associated with restaurants or events, jalapeño peppers were implicated in all three clusters with implicated ingredients, and jalapeño or serrano peppers were an ingredient in an implicated item in the other three clusters. Raw tomatoes were an ingredient in an implicated item in three clusters. The outbreak strain was identified in jalapeño peppers collected in Texas and in agricultural water and serrano peppers on a Mexican farm. Tomato tracebacks did not converge on a source. CONCLUSIONS: Although an epidemiologic association with raw tomatoes was identified early in this investigation, subsequent epidemiologic and microbiologic evidence implicated jalapeño and serrano peppers. This outbreak highlights the importance of preventing raw-produce contamination.

Multilocus sequence typing confirms wild birds as the source of a Campylobacter outbreak associated with the consumption of raw peas.

From August to September 2008, the Centers for Disease Control and Prevention (CDC) assisted the Alaska Division of Public Health with an outbreak investigation of campylobacteriosis occurring among the residents of Southcentral Alaska. During the investigation, pulsed-field gel electrophoresis (PFGE) of Campylobacter jejuni isolates from human, raw pea, and wild bird fecal samples confirmed the epidemiologic link between illness and the consumption of raw peas contaminated by sandhill cranes for 15 of 43 epidemiologically linked human isolates. However, an association between the remaining epidemiologically linked human infections and the pea and wild bird isolates was not established. To better understand the molecular epidemiology of the outbreak, C. jejuni isolates (n=130; 59 from humans, 40 from peas, and 31 from wild birds) were further characterized by multilocus sequence typing (MLST). Here we present the molecular evidence to demonstrate the association of many more human C.jejuni infections associated with the outbreak with raw peas and wild bird feces. Among all sequence types (STs) identified, 26 of 39 (67%) were novel and exclusive to the outbreak. Five clusters of overlapping STs (n=32 isolates; 17 from humans, 2 from peas, and 13 from wild birds) were identified. In particular, cluster E (n=7 isolates; ST-5049) consisted of isolates from humans,peas, and wild birds. Novel STs clustered closely with isolates typically associated with wild birds and the environment but distinct from lineages commonly seen in human infections. Novel STs and alleles recovered from human outbreak isolates allowed additional infections caused by these rare genotypes to be attributed to the contaminated raw peas.

Campylobacter fetus subsp. testudinum subsp. nov., isolated from humans and reptiles.

A polyphasic study was undertaken to determine the taxonomic position of 13 Campylobacter fetus-like strains from humans (n = 8) and reptiles (n = 5). The results of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS and genomic data from sap analysis, 16S rRNA gene and hsp60 sequence comparison, pulsed-field gel electrophoresis, amplified fragment length polymorphism analysis, DNA-DNA hybridization and whole genome sequencing demonstrated that these strains are closely related to C. fetus but clearly differentiated from recognized subspecies of C. fetus. Therefore, this unique cluster of 13 strains represents a novel subspecies within the species C. fetus, for which the name Campylobacter fetus subsp. testudinum subsp. nov. is proposed, with strain 03-427(T) ( = ATCC BAA-2539(T) = LMG 27499(T)) as the type strain. Although this novel taxon could not be differentiated from C. fetus subsp. fetus and C. fetus subsp. venerealis using conventional phenotypic tests, MALDI-TOF MS revealed the presence of multiple phenotypic biomarkers which distinguish Campylobacter fetus subsp. testudinum subsp. nov. from recognized subspecies of C. fetus.

Outbreaks caused by sprouts, United States, 1998-2010: lessons learned and solutions needed.

After a series of outbreaks associated with sprouts in the mid-1990s, the U.S. Food and Drug Administration (FDA) published guidelines in 1999 for sprouts producers to reduce the risk of contamination. The recommendations included treating seeds with an antimicrobial agent such as calcium hypochlorite solution and testing spent irrigation water for pathogens. From 1998 through 2010, 33 outbreaks from seed and bean sprouts were documented in the United States, affecting 1330 reported persons. Twenty-eight outbreaks were caused by Salmonella, four by Shiga toxin-producing Escherichia coli, and one by Listeria. In 15 of the 18 outbreaks with information available, growers had not followed key FDA guidelines. In three outbreaks, however, the implicated sprouts were produced by firms that appeared to have implemented key FDA guidelines. Although seed chlorination, if consistently applied, reduces pathogen burden on sprouts, it does not eliminate the risk of human infection. Further seed and sprouts disinfection technologies, some recently developed, will be needed to enhance sprouts safety and reduce human disease. Improved seed production practices could also decrease pathogen burden but, because seeds are a globally distributed commodity, will require international cooperation.

Human infections with new subspecies of Campylobacter fetus.

Campylobacter fetus subsp. testudinum subsp. nov. is a newly proposed subspecies of C. fetus with markers of reptile origin. We summarize epidemiologic information for 9 humans infected with this bacterium. All cases were in men, most of whom were of Asian origin. Infection might have been related to exposure to Asian foods or reptiles.

Attribution of foodborne illnesses, hospitalizations, and deaths to food commodities by using outbreak data, United States, 1998-2008.

Each year, >9 million foodborne illnesses are estimated to be caused by major pathogens acquired in the United States. Preventing these illnesses is challenging because resources are limited and linking individual illnesses to a particular food is rarely possible except during an outbreak. We developed a method of attributing illnesses to food commodities that uses data from outbreaks associated with both simple and complex foods. Using data from outbreak-associated illnesses for 1998-2008, we estimated annual US foodborne illnesses, hospitalizations, and deaths attributable to each of 17 food commodities. We attributed 46% of illnesses to produce and found that more deaths were attributed to poultry than to any other commodity. To the extent that these estimates reflect the commodities causing all foodborne illness, they indicate that efforts are particularly needed to prevent contamination of produce and poultry. Methods to incorporate data from other sources are needed to improve attribution estimates for some commodities and agents.

Emergence of salsa and guacamole as frequent vehicles of foodborne disease outbreaks in the United States, 1973-2008.

Fresh salsa and guacamole often contain diced raw produce, are often made in large batches, and are often poorly refrigerated, which may make them prone to contamination that can cause foodborne illness. The safety of salsa and guacamole is increasingly important as these foods gain popularity. Since 1973, local, state, and territorial health departments have voluntarily reported foodborne disease outbreaks to the Centers for Disease Control and Prevention's Foodborne Disease Outbreak Surveillance System (FDOSS) using a standard reporting form. FDOSS used paper-based reporting for 1973-1997 and switched to electronic reporting for 1998-2008. We reviewed all reports of outbreaks during 1973-2008 in which salsa or guacamole was reported as a vehicle. We found 136 outbreaks in which salsa or guacamole was reported as a possible vehicle, which resulted in 5,658 illnesses. Of these 136 salsa- or guacamole-associated (SGA) outbreaks additional possible food vehicles were reported for 33 (24%) outbreaks. There were no SGA outbreaks reported before 1984. Among reported outbreaks, most were caused by norovirus (24%), nontyphoidal Salmonella (19%), and Shigella (7%). Eighty-four percent of outbreaks were caused by foods prepared in restaurants or delis; of these, 19% reported ill foodworkers, and 29% reported improper storage as possible contributing factors. Among all foodborne disease outbreaks with a reported food vehicle during 1984-1997, 26 (0.9%) of 2,966 outbreaks were SGA, and during 1998-2008, 110 (1.4%) of 7,738 outbreaks were SGA. The number of reported foodborne disease outbreaks attributable to salsa or guacamole increased in the United States from 1984 to 2008, especially in later years, and especially in restaurants. Fresh salsa and guacamole require careful preparation and storage. Focused prevention strategies should reduce the risk of illness and ensure that these foods are enjoyed safely.

Do differences in risk factors, medical care seeking, or medical practices explain the geographic variation in campylobacteriosis in Foodborne Diseases Active Surveillance Network (FoodNet) sites?

BACKGROUND: In the United States, considerable geographic variation in the rates of culture-confirmed Campylobacter infection has been consistently observed among sites participating in the Foodborne Diseases Active Surveillance Network (FoodNet). METHODS: We used data from the FoodNet Population Surveys and a FoodNet case-control study of sporadic infection to examine whether differences in medical care seeking, medical practices, or risk factors contributed to geographic variation in incidence. RESULTS: We found differences across the FoodNet sites in the proportion of persons seeking medical care for an acute campylobacteriosis-like illness (range, 24.9%-43.5%) and in the proportion of ill persons who submitted a stool sample (range, 18.6%-40.7%), but these differences were not statistically significant. We found no evidence of geographic effect modification of previously identified risk factors for campylobacteriosis in the case-control study analysis. The prevalence of some exposures varied among control subjects in the FoodNet sites, including the proportion of controls reporting eating chicken at a commercial eating establishment (18.2%-46.1%); contact with animal stool (8.9%-30.9%); drinking water from a lake, river, or stream (0%-5.1%); and contact with a farm animal (2.1%-12.7%). However, these differences do not fully explain the geographic variation in campylobacteriosis. CONCLUSIONS: Future studies that quantify Campylobacter contamination in poultry or variation in host immunity may be useful in identifying sources of this geographic variation in incidence.

Preventing maritime transfer of toxigenic Vibrio cholerae.

Organisms, including Vibrio cholerae, can be transferred between harbors in the ballast water of ships. Zones in the Caribbean region where distance from shore and water depth meet International Maritime Organization guidelines for ballast water exchange are extremely limited. Use of ballast water treatment systems could mitigate the risk for organism transfer.

Lessons learned during public health response to cholera epidemic in Haiti and the Dominican Republic.

After epidemic cholera emerged in Haiti in October 2010, the disease spread rapidly in a country devastated by an earthquake earlier that year, in a population with a high proportion of infant deaths, poor nutrition, and frequent infectious diseases such as HIV infection, tuberculosis, and malaria. Many nations, multinational agencies, and nongovernmental organizations rapidly mobilized to assist Haiti. The US government provided emergency response through the Office of Foreign Disaster Assistance of the US Agency for International Development and the Centers for Disease Control and Prevention. This report summarizes the participation by the Centers and its partners. The efforts needed to reduce the spread of the epidemic and prevent deaths highlight the need for safe drinking water and basic medical care in such difficult circumstances and the need for rebuilding water, sanitation, and public health systems to prevent future epidemics.