Epidemiologic patterns of human Salmonella serotype diversity in the USA, 1996-2016.

Although researchers have described numerous risk factors for salmonellosis and for infection with specific common serotypes, the drivers of Salmonella serotype diversity among human populations remain poorly understood. In this retrospective observational study, we partition records of serotyped non-typhoidal Salmonella isolates from human clinical specimens reported to CDC national surveillance by demographic, geographic and seasonal characteristics and adapt sample-based rarefaction methods from the field of community ecology to study how Salmonella serotype diversity varied within and among these populations in the USA during 1996-2016. We observed substantially higher serotype richness in children <2 years old than in older children and adults and steadily increasing richness with age among older adults. Whereas seasonal and regional variation in serotype diversity was highest among infants and young children, variation by specimen source was highest in adults. Our findings suggest that the risk for infection from uncommon serotypes is associated with host and environmental factors, particularly among infants, young children and older adults. These populations may have a higher proportion of illness acquired through environmental transmission pathways than published source attribution models estimate.

Post-Campylobacter Guillain Barré Syndrome in the USA: secondary analysis of surveillance data collected during the 2009-2010 novel Influenza A (H1N1) vaccination campaign.

Guillain Barré syndrome (GBS), which is triggered by autoantibodies produced in response to antigenic stimuli such as certain infections and vaccinations, is the most common cause of acute flaccid paralysis worldwide. Campylobacter, the most common bacterial enteric infection in the USA, is reported to be the most commonly diagnosed antecedent of GBS, yet little information is available about the risk of post-Campylobacter GBS. Data collected through active, population-based surveillance in the Emerging Infections Program during the 2009-2010 novel Influenza A (H1N1) vaccination campaign allowed us to compare confirmed and probable GBS cases to non-cases to determine whether antecedent Campylobacter infection (or a diarrhoeal illness consistent with campylobacteriosis) was more common among cases and to assess the risk of GBS following Campylobacter infection. We estimate that 8-12% of GBS cases in the USA are attributable to Campylobacter infection (or a diarrhoeal illness consistent with campylobacteriosis), with 434-650 cases of post-diarrhoeal GBS annually and about 49 cases of GBS per 100 000 Campylobacter infections. These results provide updated estimates for post-Campylobacter GBS incidence in the USA and highlight an important benefit of effective measures to prevent Campylobacter infections.

Hospitalisations due to bacterial gastroenteritis: A comparison of surveillance and hospital discharge data.

Studies estimating the human health impact of the foodborne disease often include estimates of the number of gastroenteritis hospitalisations. The aims of this study were to examine the degree to which hospital discharge data underreport hospitalisations due to bacterial gastroenteritis and to estimate the frequency of stool sample submission among patients presenting with gastroenteritis. Using linked laboratory and hospital discharge data from a healthcare organisation and its affiliated hospital, we examined the International Classification of Disease (ICD-9-CM) diagnosis codes assigned to hospitalised adults with culture-confirmed Campylobacter, Salmonella, or Escherichia coli O157 infections and determined the frequency of stool sample submission. Among 138 hospitalised patients with culture-confirmed infections, 43% of Campylobacter patients, 56% of Salmonella patients and 35% of E. coli O157 patients had that pathogen-specific code listed on the discharge record. Among patients without their infection listed as a diagnosis, 65% were assigned a nonspecific gastroenteritis code. Submitting a specimen for culture ⩾3 days before discharge was significantly associated with having the pathogen-specific diagnosis listed. Of 6181 patients assigned a nonspecific gastroenteritis code, 69% had submitted a stool sample for bacterial culture. This study can be used to understand differences and adjust for the underreporting and underdiagnosed of Campylobacter, Salmonella and E. coli O157 in hospital discharge and surveillance data, respectively.

Features of illnesses caused by five species of Campylobacter, Foodborne Diseases Active Surveillance Network (FoodNet) - 2010-2015.

The Foodborne Diseases Active Surveillance Network (FoodNet) conducts population-based surveillance for Campylobacter infection. For 2010 through 2015, we compared patients with Campylobacter jejuni with patients with infections caused by other Campylobacter species. Campylobacter coli patients were more often >40 years of age (OR = 1·4), Asian (OR = 2·3), or Black (OR = 1·7), and more likely to live in an urban area (OR = 1·2), report international travel (OR = 1·5), and have infection in autumn or winter (OR = 1·2). Campylobacter upsaliensis patients were more likely female (OR = 1·6), Hispanic (OR = 1·6), have a blood isolate (OR = 2·8), and have an infection in autumn or winter (OR = 1·7). Campylobacter lari patients were more likely to be >40 years of age (OR = 2·9) and have an infection in autumn or winter (OR = 1·7). Campylobacter fetus patients were more likely male (OR = 3·1), hospitalized (OR = 3·5), and have a blood isolate (OR = 44·1). International travel was associated with antimicrobial-resistant C. jejuni (OR = 12·5) and C. coli (OR = 12) infections. Species-level data are useful in understanding epidemiology, sources, and resistance of infections.

Vibrio alginolyticus infections in the USA, 1988-2012.

Vibrio alginolyticus causes soft tissue and bloodstream infection; little systematically collected clinical and epidemiological information is available. In the USA, V. alginolyticus infections are reported to the Cholera and Other Vibrio Illness Surveillance system. Using data from 1988 to 2012, we categorised infections using specimen source and exposure history, analysed case characteristics, and calculated incidence rates using US Census Bureau data. Most (96%) of the 1331 V. alginolyticus infections were from coastal states. Infections of the skin and ear were most frequent (87%); ear infections occurred more commonly in children, lower extremity infections more commonly in older adults. Most (86%) infections involved water activity. Reported incidence of infections increased 12-fold over the study period, although the extent of diagnostic or surveillance bias is unclear. Prevention efforts should target waterborne transmission in coastal areas and provider education to promote more rapid diagnosis and prevent complications.

Poultry: the most common food in outbreaks with known pathogens, United States, 1998-2012.

As poultry consumption continues to increase worldwide, and as the United States accounts for about one-third of all poultry exports globally, understanding factors leading to poultry-associated foodborne outbreaks in the United States has important implications for food safety. We analysed outbreaks reported to the United States' Foodborne Disease Outbreak Surveillance System from 1998 to 2012 in which the implicated food or ingredient could be assigned to one food category. Of 1114 outbreaks, poultry was associated with 279 (25%), accounting for the highest number of outbreaks, illnesses, and hospitalizations, and the second highest number of deaths. Of the 149 poultry-associated outbreaks caused by a confirmed pathogen, Salmonella enterica (43%) and Clostridium perfringens (26%) were the most common pathogens. Restaurants were the most commonly reported location of food preparation (37% of poultry-associated outbreaks), followed by private homes (25%), and catering facilities (13%). The most commonly reported factors contributing to poultry-associated outbreaks were food-handling errors (64%) and inadequate cooking (53%). Effective measures to reduce poultry contamination, promote safe food-handling practices, and ensure food handlers do not work while ill could reduce poultry-associated outbreaks and illnesses.

Vibriosis, not cholera: toxigenic Vibrio cholerae non-O1, non-O139 infections in the United States, 1984-2014.

Toxigenic strains of Vibrio cholerae serogroups O1 and O139 have caused cholera epidemics, but other serogroups - such as O75 or O141 - can also produce cholera toxin and cause severe watery diarrhoea similar to cholera. We describe 31 years of surveillance for toxigenic non-O1, non-O139 infections in the United States and map these infections to the state where the exposure probably originated. While serogroups O75 and O141 are closely related pathogens, they differ in how and where they infect people. Oysters were the main vehicle for O75 infection. The vehicles for O141 infection include oysters, clams, and freshwater in lakes and rivers. The patients infected with serogroup O75 who had food traceback information available ate raw oysters from Florida. Patients infected with O141 ate oysters from Florida and clams from New Jersey, and those who only reported being exposed to freshwater were exposed in Arizona, Michigan, Missouri, and Texas. Improving the safety of oysters, specifically, should help prevent future illnesses from these toxigenic strains and similar pathogenic Vibrio species. Post-harvest processing of raw oysters, such as individual quick freezing, heat-cool pasteurization, and high hydrostatic pressurization, should be considered.

The rise and decline in Salmonella enterica serovar Enteritidis outbreaks attributed to egg-containing foods in the United States, 1973-2009.

Salmonella enterica causes an estimated 1 million domestically acquired foodborne illnesses annually. Salmonella enterica serovar Enteritidis (SE) is among the top three serovars of reported cases of Salmonella. We examined trends in SE foodborne outbreaks from 1973 to 2009 using Joinpoint and Poisson regression. The annual number of SE outbreaks increased sharply in the 1970s and 1980s but declined significantly after 1990. Over the study period, SE outbreaks were most frequently attributed to foods containing eggs. The average rate of SE outbreaks attributed to egg-containing foods reported by states began to decline significantly after 1990, and the proportion of SE outbreaks attributed to egg-containing foods began declining after 1997. Our results suggest that interventions initiated in the 1990s to decrease SE contamination of shell eggs may have been integral to preventing SE outbreaks.

An assessment of the human health impact of seven leading foodborne pathogens in the United States using disability adjusted life years.

We explored the overall impact of foodborne disease caused by seven leading foodborne pathogens in the United States using the disability adjusted life year (DALY). We defined health states for each pathogen (acute illness and sequelae) and estimated the average annual incidence of each health state using data from public health surveillance and previously published estimates from studies in the United States, Canada and Europe. These pathogens caused about 112 000 DALYs annually due to foodborne illnesses acquired in the United States. Non-typhoidal Salmonella (32 900) and Toxoplasma (32 700) caused the most DALYs, followed by Campylobacter (22 500), norovirus (9900), Listeria monocytogenes (8800), Clostridium perfringens (4000), and Escherichia coli O157 (1200). These estimates can be used to prioritize food safety interventions. Future estimates of the burden of foodborne disease in DALYs would be improved by addressing important data gaps and by the development and validation of US-specific disability weights for foodborne diseases.

Typhoid fever acquired in the United States, 1999-2010: epidemiology, microbiology, and use of a space-time scan statistic for outbreak detection.

Although rare, typhoid fever cases acquired in the United States continue to be reported. Detection and investigation of outbreaks in these domestically acquired cases offer opportunities to identify chronic carriers. We searched surveillance and laboratory databases for domestically acquired typhoid fever cases, used a space-time scan statistic to identify clusters, and classified clusters as outbreaks or non-outbreaks. From 1999 to 2010, domestically acquired cases accounted for 18% of 3373 reported typhoid fever cases; their isolates were less often multidrug-resistant (2% vs. 15%) compared to isolates from travel-associated cases. We identified 28 outbreaks and two possible outbreaks within 45 space-time clusters of ⩾2 domestically acquired cases, including three outbreaks involving ⩾2 molecular subtypes. The approach detected seven of the ten outbreaks published in the literature or reported to CDC. Although this approach did not definitively identify any previously unrecognized outbreaks, it showed the potential to detect outbreaks of typhoid fever that may escape detection by routine analysis of surveillance data. Sixteen outbreaks had been linked to a carrier. Every case of typhoid fever acquired in a non-endemic country warrants thorough investigation. Space-time scan statistics, together with shoe-leather epidemiology and molecular subtyping, may improve outbreak detection.

Cholera in the United States, 2001-2011: a reflection of patterns of global epidemiology and travel.

US cholera surveillance offers insight into global and domestic trends. Between 2001 and 2011, 111 cases were reported to the Centers for Disease Control and Prevention. Cholera was associated with international travel in 90 (81%) patients and was domestically acquired in 20 (18%) patients; for one patient, information was not available. From January 2001 to October 2010, the 42 (47%) travel-associated cases were associated with travel to Asia. In October 2010, a cholera epidemic started in Haiti, soon spreading to the Dominican Republic (Hispaniola). From then to December 2011, 40 (83%) of the 48 travel-associated cases were associated with travel to Hispaniola. Of 20 patients who acquired cholera domestically, 17 (85%) reported seafood consumption; 10 (59%) ate seafood from the US Gulf Coast. In summary, an increase in travel-associated US cholera cases was associated with epidemic cholera in Hispaniola in 2010-2011. Travel to Asia and consumption of Gulf Coast seafood remained important sources of US cholera cases.

Clam-associated vibriosis, USA, 1988-2010.

Infections with Vibrio spp. have frequently been associated with consumption of bivalve molluscs, especially oysters, but illness associated with clams has also been well documented. We describe the 2312 domestically acquired foodborne Vibrio infections reported to the Cholera and Other Vibrio Illness Surveillance system from 1988 to 2010. Clams were associated with at least 4% (93 persons, 'only clams') and possibly as many as 24% (556 persons, 'any clams') of foodborne cases. Of those who consumed 'only clams', 77% of infections were caused by V. parahaemolyticus. Clam-associated illnesses were generally similar to those associated with other seafood consumption. Clams associated with these illnesses were most frequently harvested from the Atlantic coastal states and eaten raw. Our study describes the contribution of clams to the overall burden of foodborne vibriosis and indicates that a comprehensive programme to prevent foodborne vibriosis need to address the risks associated with clams.

Common source outbreaks of Campylobacter infection in the USA, 1997-2008.

Campylobacter is a common but decreasing cause of foodborne infections in the USA. Outbreaks are uncommon and have historically differed from sporadic cases in seasonality and contamination source. We reviewed reported outbreaks of campylobacteriosis. From 1997 to 2008, 262 outbreaks were reported, with 9135 illnesses, 159 hospitalizations, and three deaths. The annual mean was 16 outbreaks for 1997-2002, and 28 outbreaks for 2003-2008. Almost half occurred in warmer months. Foodborne transmission was reported in 225 (86%) outbreaks, water in 24 (9%), and animal contact in seven (3%). Dairy products were implicated in 65 (29%) foodborne outbreaks, poultry in 25 (11%), and produce in 12 (5%). Reported outbreaks increased during a period of declining overall incidence, and seasonality of outbreaks resembled that of sporadic infections. Unlike sporadic illnesses, which are primarily attributed to poultry, dairy products are the most common vehicle identified for outbreaks.

Maternal and infant use of erythromycin and other macrolide antibiotics as risk factors for infantile hypertrophic pyloric stenosis.

OBJECTIVES: To evaluate the risk for infantile hypertrophic pyloric stenosis (IHPS) among infants prescribed systemic erythromycin, infants prescribed a course of erythromycin ophthalmic ointment, and infants whose mothers were prescribed a macrolide antibiotic during pregnancy. STUDY DESIGN: Retrospective cohort study of infants born at an urban hospital from June 1993 through December 1999. RESULTS: Of 14,876 eligible infants, 43 (0.29%) developed IHPS. Infants prescribed systemic erythromycin had increased risk of IHPS, with the highest risk in the first 2 weeks of age (relative risk = 10.51 for erythromycin in first 2 weeks, 95% CI 4.48, 24.66). Erythromycin ophthalmic ointment for conjunctivitis was not associated with increased risk of IHPS. Maternal macrolide antibiotics within 10 weeks of delivery may have been associated with higher risk of IHPS but the data were not conclusive. CONCLUSIONS: This study confirms an association between systemic erythromycin in infants and subsequent IHPS, with the highest risk in the first 2 weeks of age. No association was found with erythromycin ophthalmic ointment. A possible association with maternal macrolide therapy in late pregnancy requires further study. Systemic erythromycin should be used with prudence in early infancy.

Surveying vendors of street-vended food: a new methodology applied in two Guatemalan cities.

Lack of reliable data about street vendors, who are difficult to survey, has hampered efforts to improve the safety of street-vended food. A two-phase method for sampling vendors, surveying first in areas of concentrated vending activity identified by local authorities and second in randomly selected areas, was developed and implemented in two Guatemalan cities where street-vended food had been implicated in cholera transmission. In a 4-day survey in Escuintla, 59 vendors (42 from phase 1, 17 from phase 2) were interviewed. They demonstrated good knowledge of food safety and cholera but unsafe practices, implying that more effective, practical training was needed. In a 6-day survey in Guatemala City, 78 vendors (77 from phase 1, 1 from phase 2) were interviewed. Sixty-eight (87 %) vendors stored water, usually in wide-mouthed vessels prone to contamination; this led to a field test of a new system for safe water storage. Useful information for public health planning and intervention can be gathered rapidly with this new method for surveying street vendors.

Consequences in Georgia of a nationwide outbreak of Salmonella infections: what you don't know might hurt you.

OBJECTIVES: This study assessed the impact in Georgia of a nationwide salmonellosis outbreak caused by ice cream products and the effectiveness of the subsequent warning against eating the implicated products. METHODS: A telephone survey of 250 randomly selected Georgia customers of the ice cream producer was conducted 13 to 17 days after the warning. RESULTS: Respondents from 179 households representing 628 persons were interviewed. The median date of first hearing the warning was 5 days after it was issued, and 16 respondents (9%) had not heard it. Among those who had heard the warning, 42 (26%) did not initially believe the products were unsafe. In 22 (31%) of the 72 households that had the implicated ice cream when the respondent heard the warning, someone subsequently ate the ice cream. Diarrhea was reported in 26% (121/463) of persons who had eaten the products but in only 5% (8/152) who had not (odds ratio [controlling for household clustering] = 3.8; 95% confidence interval = 2.0, 7.5). We estimate this outbreak caused 11,000 cases of diarrhea in Georgia, 1760 (16%) with exposure after the warning. CONCLUSIONS: A large outbreak occurred in Georgia, much of which might have been prevented by a more timely and convincing warning.

An outbreak of Escherichia coli O157:H7 infections associated with leaf lettuce consumption.

In July 1995, 40 Montana residents were identified with laboratory-confirmed Escherichia coli O157:H7 infection; 52 residents had bloody diarrhea without laboratory confirmation. The median age of those with laboratory-confirmed cases was 42 years (range, 4- 86); 58% were female. Thirteen patients were hospitalized, and 1 developed hemolytic-uremic syndrome. A case-control study showed that 19 (70%) of 27 patients but only 8 (17%) of 46 controls reported eating purchased (not home-grown) leaf lettuce before illness (matched odds ratio, 25.3; 95% confidence interval, 3.9-1065.6). Pulsed-field gel electrophoresis identified a common strain among 22 of 23 isolates tested. Implicated lettuce was traced to two sources: a local Montana farm and six farms in Washington State that shipped under the same label. This outbreak highlights the increasing importance of fresh produce as a vehicle in foodborne illness. Sanitary growing and handling procedures are necessary to prevent these infections.

An international outbreak of Salmonella infections caused by alfalfa sprouts grown from contaminated seeds.

An outbreak of Salmonella serotype stanley infections occurred in the United States and Finland in 1995. The outbreak was investigated through case-control studies in Arizona, Michigan, and Finland; by isolate subtyping; and by tracing and culturing of the implicated food. Alfalfa sprout consumption was the only exposure associated with S. stanley infections in Arizona (matched odds ratio [MOR] = 11.1; 95% confidence interval [CI], 1.4-513), Michigan (MOR = 5.5; CI, 1.6-23), and Finland (MOR undefined; CI, 4.9-infinity). US and Finnish patient isolates were a unique outbreak strain distinct from S. stanley isolates not linked to the outbreak. Alfalfa sprouts eaten by patients in 6 US states and Finland were traced to seed shipped by a Dutch shipper. Thus, it was concluded that alfalfa sprouts grown from contaminated seed caused an international outbreak of > or =242 S. stanley infections in > or =17 US states and Finland. This outbreak illustrates a new mechanism through which contamination of fresh produce can cause large, widely dispersed outbreaks.

Efficacy of chlorine and heat treatment in killing Salmonella stanley inoculated onto alfalfa seeds and growth and survival of the pathogen during sprouting and storage.

The efficacy of chlorine and hot water treatments in killing Salmonella stanley inoculated onto alfalfa seeds was determined. Treatment of seeds containing 10(2) to 10(3) CFU/g in 100-micrograms/ml active chlorine solution for 5 or 10 min caused a significant (P < or = 0.05) reduction in population, and treatment in 290-micrograms/ml chlorine solution resulted in a significant reduction compared with treatment in 100 micrograms of chlorine per ml. However, concentrations of chlorine of up to 1,010 micrograms/ml failed to result in further significant reductions. Treatment of seeds containing 10(1) to 10(2) CFU of S. stanley per g for 5 min in a solution containing 2,040 micrograms of chlorine per ml reduced the population to undetectable levels (< 1 CFU/g). Treatment of seeds in water for 5 or 10 min at 54 degrees C caused a significant reduction in the S. stanley population, and treatment at > or = 57 degrees C reduced populations to < or = 1 CFU/g. However, treatment at > or = 54 degrees C for 10 min caused a substantial reduction in viability of the seeds. Treatment at 57 or 60 degrees C for 5 min appears to be effective in killing S. stanley without substantially decreasing germinability of seeds. Storage of seeds for 8 to 9 weeks at 8 and 21 degrees C resulted in reductions in populations of S. stanley of about 1 log10 and 2 log10 CFU/g, respectively. The behavior of S. stanley on seeds during soaking germination, sprouting, and refrigerated storage of sprouts was determined. An initial population of 3.29 log10 CFU/g increased slightly during 6 h of soaking, by about 10(3) CFU/g during a 24-h germination period, and by an additional 10 CFU/g during a 72-h sprouting stage. A population of 10(7) CFU/g of mature alfalfa sprouts was detected throughout a subsequent 10-day storage period at 5 degrees C. These studies indicate that while populations of S. stanley can be greatly reduced, elimination of this organism from alfalfa seeds may not be reliably achieved with traditional disinfection procedures. If S. stanley is present on seeds at the initiation of the sprout production process, populations exceeding 10(7) CFU/g can develop and survive on mature sprouts exposed to handling practices used in commercial production and marketing.