Using the Electronic Foodborne Outbreak Reporting System (eFORS) to improve foodborne outbreak surveillance, investigations, and program evaluation.

Challenges exist in comparing foodborne disease outbreaks (FBDOs) across states due to important differences in reporting practices and investigations. Variables such as FBDO size, population size, number of tourists, and suspected etiology are important to consider when interpreting FBDO data. Analysis of eFORS data can be valuable in improving state FBDO investigations. From 2000 to 2005, Florida reported a greater proportion of FBDOs, with two cases per outbreak, than the U.S. as a whole (40.4% in Florida vs. 17.2% in the U.S.). Reporting a higher rate of small FBDOs provided more opportunities for public health interventions but contributed to a lower agent confirmation rate (17.0% in Florida vs. 42.2% in the U.S.). While the Electronic Foodborne Outbreak Reporting System's (eFORS) database brought great improvements in national FBDO surveillance, as with any complex surveillance system, considerable knowledge and specialized expertise is required to properly analyze and interpret the data, especially because there is a large variation in state reports to eFORS.

Acute selenium toxicity associated with a dietary supplement.

BACKGROUND: Selenium is an element necessary for normal cellular function, but it can have toxic effects at high doses. We investigated an outbreak of acute selenium poisoning. METHODS: A case was defined as the onset of symptoms of selenium toxicity in a person within 2 weeks after ingesting a dietary supplement manufactured by "Company A," purchased after January 1, 2008. We conducted case finding, administered initial and 90-day follow-up questionnaires to affected persons, and obtained laboratory data where available. RESULTS: The source of the outbreak was identified as a liquid dietary supplement that contained 200 times the labeled concentration of selenium. Of 201 cases identified in 10 states, 1 person was hospitalized. The median estimated dose of selenium consumed was 41 749 microg/d (recommended dietary allowance is 55 microg/d). Frequently reported symptoms included diarrhea (78%), fatigue (75%), hair loss (72%), joint pain (70%), nail discoloration or brittleness (61%), and nausea (58%). Symptoms persisting 90 days or longer included fingernail discoloration and loss (52%), fatigue (35%), and hair loss (29%). The mean initial serum selenium concentration of 8 patients was 751 microg/L (reference range, < or =125 microg/L). The mean initial urine selenium concentration of 7 patients was 166 microg/24 h (reference range, < or =55 microg/24 h). CONCLUSIONS: Toxic concentrations of selenium in a liquid dietary supplement resulted in a widespread outbreak. Had the manufacturers been held to standards used in the pharmaceutical industry, it may have been prevented.

Neurotoxic shellfish poisoning.

Neurotoxic shellfish poisoning (NSP) is caused by consumption of molluscan shellfish contaminated with brevetoxins primarily produced by the dinoflagellate, Karenia brevis. Blooms of K. brevis, called Florida red tide, occur frequently along the Gulf of Mexico. Many shellfish beds in the US (and other nations) are routinely monitored for presence of K. brevis and other brevetoxin-producing organisms. As a result, few NSP cases are reported annually from the US. However, infrequent larger outbreaks do occur. Cases are usually associated with recreationally-harvested shellfish collected during or post red tide blooms. Brevetoxins are neurotoxins which activate voltage-sensitive sodium channels causing sodium influx and nerve membrane depolarization. No fatalities have been reported, but hospitalizations occur. NSP involves a cluster of gastrointestinal and neurological symptoms: nausea and vomiting, paresthesias of the mouth, lips and tongue as well as distal paresthesias, ataxia, slurred speech and dizziness. Neurological symptoms can progress to partial paralysis; respiratory distress has been recorded. Recent research has implicated new species of harmful algal bloom organisms which produce brevetoxins, identified additional marine species which accumulate brevetoxins, and has provided additional information on the toxicity and analysis of brevetoxins. A review of the known epidemiology and recommendations for improved NSP prevention are presented.

Cryptosporidiosis outbreak in a Nassau County, Florida, return travel group from Ireland, May 24, 2006-June 4, 2006.

The Nassau County Health Department (NCHD) in Florida investigated an outbreak of gastrointestinal (GI) illness in a returning choral group who toured Ireland from May 24 to June 4, 2006. The travel group, consisting predominantly of retirees, had performed at several churches and at a dinner theater in Ireland. The NCHD administered a telephone questionnaire to 40 of the 41 group members to examine possible water exposures; common meals; and food, travel, and clinical histories. The results of the questionnaire showed that 29 people met the case definition for the outbreak. Five stool samples from travel group members tested positive for Cryptosporidium parvum, a species that is animal in origin and often spread through an environmental contamination with animal feces. All five positive samples were subtyped 11aA16G1R1b, a strain that scientists at the Centers for Disease Control and Prevention (CDC) Division of Parasitic Diseases detected twice in 2006 in other human specimens from Northern Ireland.

Use of molecular epidemiology to confirm a multistate outbreak of hepatitis A caused by consumption of oysters.

The 39 oyster consumption-related cases of hepatitis A reported in 2005 represent the first large outbreak of hepatitis A associated with shellfish consumption in the United States in >15 years. This is the first outbreak investigation in which an identical hepatitis A virus sequence was obtained from both the implicated food product and case patients.

Outbreak bias in illness reporting and case confirmation in ciguatera fish poisoning surveillance in south Florida.

OBJECTIVE: Ciguatera fish poisoning is a potentially life-threatening disease caused by eating coral reef fish contaminated with ciguatoxins and is the most common marine poisoning. However, existing surveillance systems capture few cases. To improve regional ciguatera surveillance in South Florida, this study compared ciguatera illnesses in the Florida Poison Information Center-Miami (FPICM) call database to ciguatera cases in the Florida Department of Health (FDOH) disease surveillance systems. METHODS: Univariate and multivariate logistic regression were used to identify predictors of when FPICM reported ciguatera illnesses to FDOH and whether FDOH confirmed reported ciguatera cases. RESULTS: FPICM staff preferentially reported ciguatera illnesses that were of shorter duration (adjusted odds ratio [AOR] = 0.84 per additional illness day; 95% confidence interval [CI] 0.74, 0.97); outbreak-associated (AOR = 7.0; 95% CI 2.5, 19.5); and clinically more severe (AOR = 21.6; 95% CI 2.3, 198.5). Among ciguatera illnesses reported to FDOH, outbreak-associated illnesses were more likely than single, sporadic illnesses to become confirmed surveillance cases (crude OR = 11.1; 95% CI 2.0, 62.5). CONCLUSIONS: The over-representation of outbreak-associated ciguatera cases underestimates the true contribution of sporadic illnesses to ciguatera disease burden. This bias should be considered when evaluating surveillance systems that include both outbreak-associated and sporadic illness reports.

Assessing the effectiveness of food worker training in Florida: opportunities and challenges.

The task of measuring the effectiveness of food worker training has historically met with many challenges. This paper considers various approaches and utilizes trends in foodborne-outbreak contributing factors to evaluate a recent change in Florida's food worker training. Results show that subsequent to training, the relative incidence of many factors that contribute to foodborne outbreaks actuay increased, while the relative incidence of other factors decreased. The overall rate of foodborne outbreaks associated with the contributing factors that the authors studied decreased subsequent to training. Results of this analysis must be interpreted with caution because of multiple confounding factors; however, it became apparent that both increases and decreases in the occurrence of contributing factors could be used to focus future training material on areas of food handler practices in which it is needed. Further work needs to be done to estabish the most useful methods and approaches for assessing effectiveness and hence the public health impact of food worker training.

Web-based investigation of multistate salmonellosis outbreak.

We investigated a large outbreak of Salmonella enterica serotype Javiana among attendees of the 2002 U.S. Transplant Games, including 1,500 organ transplant recipients. Web-based survey methods identified pre-diced tomatoes as the source of this outbreak, which highlights the utility of such investigative tools to cope with the changing epidemiology of foodborne diseases.

Norovirus and foodborne disease, United States, 1991-2000.

Efforts to prevent foodborne illness target bacterial pathogens, yet noroviruses (NoV) are suspected to be the most common cause of gastroenteritis. New molecular assays allow for better estimation of the role of NoV in foodborne illness. We analyzed 8,271 foodborne outbreaks reported to the Centers for Disease Control and Prevention from 1991 to 2000 and additional data from 6 states. The proportion of NoV-confirmed outbreaks increased from 1% in 1991 to 12% in 2000. However, from 1998 to 2000, 76% of NoV outbreaks were reported by only 11 states. In 2000, an estimated 50% of foodborne outbreaks in 6 states were attributable to NoV. NoV outbreaks were larger than bacterial outbreaks (median persons affected: 25 versus 15), and 10% of affected persons sought medical care; 1% were hospitalized. More widespread use of molecular assays will permit better estimates of the role of NoV illness and help direct efforts to control foodborne illness.

An outbreak of typhoid Fever in Florida associated with an imported frozen fruit.

An outbreak of typhoid fever in Florida involving at least 16 persons during the winter of 1998-99 was investigated using case-control, environmental, and laboratory methods. The genomic profiles of Salmonella serovar Typhi (Salmonella Typhi) isolates from the 15 confirmed case subjects were identical. Consumption of fruit shakes made with frozen mamey, a tropical fruit, was significantly associated with illness (matched odds ratio, 7.6; 95% confidence interval, 1.4-81.4). Laboratory testing showed that the fruit was heavily contaminated with fecal coliforms; no Salmonella Typhi was isolated. The frozen mamey was prepared in plants in Guatemala and Honduras. No further cases occurred after the frozen product was recalled. As our nation's food sources become increasingly globalized, the risk of outbreaks of exotic diseases linked to contaminated imported food will increase. This outbreak highlights the need for new approaches to ensure the safety of our food supply.