Salmonella Outbreaks in Restaurants in Minnesota, 1995 through 2003: Evaluation of the Role of Infected Foodworkers

ABSTRACT The 23 restaurant-associated salmonellosis outbreaks that occurred in Minnesota from 1995 through 2003 were reviewed to characterize the role of infected foodworkers. The median duration of the outbreaks was 21 days (range, 1 to 517 days). The median number of culture-confirmed patron cases per outbreak was seven (range, 1 to 36 cases). The median incubation for patron cases ranged from 9 h to 5.9 days. A specific food vehicle was implicated in four outbreaks and suspected in five

Epidemiologic investigation of immune-mediated polyradiculoneuropathy among abattoir workers exposed to porcine brain

Background In October 2007, a cluster of patients experiencing a novel polyradiculoneuropathy was identified at a pork abattoir (Plant A). Patients worked in the primary carcass processing area (warm room); the majority processed severed heads (head-table). An investigation was initiated to determine risk factors for illness. Methods and Results Symptoms of the reported patients were unlike previously described occupational associated illnesses. A case-control study was conducted at Plant A. A case was defined as evidence of symptoms of peripheral neuropathy and compatible electrodiagnostic testing in a pork abattoir worker. Two control groups were used - randomly selected non-ill warm-room workers (n = 49), and all non-ill head-table workers (n = 56). Consenting cases and controls were interviewed and blood and throat swabs were collected. The 26 largest U.S. pork abattoirs were surveyed to identify additional cases. Fifteen cases were identified at Plant A; illness onsets occurred during May 2004–November 2007. Median age was 32 years (range, 21–55 years). Cases were more likely than warm-room controls to have ever worked at the head-table (adjusted odds ratio [AOR], 6.6; 95% confidence interval [CI], 1.6–26.7), removed brains or removed muscle from the backs of heads (AOR, 10.3; 95% CI, 1.5–68.5), and worked within 0–10 feet of the brain removal operation (AOR, 9.9; 95% CI, 1.2–80.0). Associations remained when comparing head-table cases and head-table controls. Workers removed brains by using compressed air that liquefied brain and generated aerosolized droplets, exposing themselves and nearby workers. Eight additional cases were identified in the only two other abattoirs using this technique. The three abattoirs that used this technique have stopped brain removal, and no new cases have been reported after 24 months of follow up. Cases compared to controls had higher median interferon-gamma (IFNγ) levels (21.7 pg/ml; vs 14.8 pg/ml, P<0.001). Discussion This novel polyradiculoneuropathy was associated with removing porcine brains with compressed air. An autoimmune mechanism is supported by higher levels of IFNγ in cases than in controls consistent with other immune mediated illnesses occurring in association with neural tissue exposure. Abattoirs should not use compressed air to remove brains and should avoid procedures that aerosolize CNS tissue. This outbreak highlights the potential for respiratory or mucosal exposure to cause an immune-mediated illness in an occupational setting

Epidemiologic investigation of immune-mediated polyradiculoneuropathy among abattoir workers exposed to porcine brain

Background In October 2007, a cluster of patients experiencing a novel polyradiculoneuropathy was identified at a pork abattoir (Plant A). Patients worked in the primary carcass processing area (warm room); the majority processed severed heads (head-table). An investigation was initiated to determine risk factors for illness. Methods and Results Symptoms of the reported patients were unlike previously described occupational associated illnesses. A case-control study was conducted at Plant A. A case was defined as evidence of symptoms of peripheral neuropathy and compatible electrodiagnostic testing in a pork abattoir worker. Two control groups were used - randomly selected non-ill warm-room workers (n = 49), and all non-ill head-table workers (n = 56). Consenting cases and controls were interviewed and blood and throat swabs were collected. The 26 largest U.S. pork abattoirs were surveyed to identify additional cases. Fifteen cases were identified at Plant A; illness onsets occurred during May 2004–November 2007. Median age was 32 years (range, 21–55 years). Cases were more likely than warm-room controls to have ever worked at the head-table (adjusted odds ratio [AOR], 6.6; 95% confidence interval [CI], 1.6–26.7), removed brains or removed muscle from the backs of heads (AOR, 10.3; 95% CI, 1.5–68.5), and worked within 0–10 feet of the brain removal operation (AOR, 9.9; 95% CI, 1.2–80.0). Associations remained when comparing head-table cases and head-table controls. Workers removed brains by using compressed air that liquefied brain and generated aerosolized droplets, exposing themselves and nearby workers. Eight additional cases were identified in the only two other abattoirs using this technique. The three abattoirs that used this technique have stopped brain removal, and no new cases have been reported after 24 months of follow up. Cases compared to controls had higher median interferon-gamma (IFNγ) levels (21.7 pg/ml; vs 14.8 pg/ml, P<0.001). Discussion This novel polyradiculoneuropathy was associated with removing porcine brains with compressed air. An autoimmune mechanism is supported by higher levels of IFNγ in cases than in controls consistent with other immune mediated illnesses occurring in association with neural tissue exposure. Abattoirs should not use compressed air to remove brains and should avoid procedures that aerosolize CNS tissue. This outbreak highlights the potential for respiratory or mucosal exposure to cause an immune-mediated illness in an occupational setting

Use of Online Consumer Complaint Forms to Enhance Complaint-Based Surveillance for Foodborne Illness Outbreaks in Minnesota

Foodborne illness complaint systems that collect consumer reports of illness following exposure at a food establishment or event are a primary tool for detecting outbreaks of foodborne illness. Approximately, 75% of outbreaks reported to the national Foodborne Disease Outbreak Surveillance System are detected through foodborne illness complaints. The Minnesota Department of Health added an online complaint form to their existing statewide foodborne illness complaint system in 2017. During 2018–2021, online complainants tended to be younger than those who used traditional telephone hotlines (mean age 39 vs 46 years; p value < 0.0001), reported illnesses sooner following onset of symptoms (mean interval 2.9 vs 4.2 days; p value = 0.003), and were more likely to still be ill at the time of the complaint (69% vs 44%; p value < 0.0001). However, online complainants were less likely to have called the suspected establishment to report their illness than those who used traditional telephone hotlines (18% vs 48%; p value < 0.0001).Of the 99 outbreaks identified by the complaint system, 67 (68%) were identified through telephone complaints alone, 20 (20%) through online complaints alone, 11 (11%) using a combination of both, and 1 (1%) through email alone. Norovirus was the most common outbreak etiology identified by both complaint system methods, accounting for 66% of outbreaks identified only via telephone complaints and 80% of outbreaks identified only via online complaints. Due to the COVID-19 pandemic in 2020, there was a 59% reduction in telephone complaint volume compared to 2019. In contrast, online complaints experienced a 25% reduction in volume. In 2021, the online method became the most popular complaint method. Although most outbreaks detected by complaints were reported by telephone complaints alone, adding an online form for complaint reporting increased the number of outbreaks detected

\u3ci\u3eSalmonella enterica\u3c/i\u3e Serotype Enteritidis: Increasing Incidence of Domestically Acquired Infections

Background. Salmonella enterica causes an estimated 1 million cases of domestically acquired foodborne illness in humans annually in the United States; Enteritidis (SE) is the most common serotype. Public health authorities, regulatory agencies, food producers, and food processors need accurate information about rates and changes in SE infection to implement and evaluate evidence-based control policies and practices. Methods. We analyzed the incidence of human SE infection during 1996–2009 in the Foodborne Diseases Active Surveillance Network (FoodNet), an active, population-based surveillance system for laboratory-confirmed infections. We compared FoodNet incidence with passively collected data from complementary surveillance systems and with rates of SE isolation from processed chickens and egg products; shell eggs are not routinely tested. We also compared molecular subtyping patterns of SE isolated from humans and chickens. Results. Since the period 1996–1999, the incidence of human SE infection in FoodNet has increased by 44%. This change is mirrored in passive national surveillance data. The greatest relative increases were in young children, older adults, and FoodNet sites in the southern United States. The proportion of patients with SE infection who reported recent international travel has decreased in recent years, whereas the proportion of chickens from which SE was isolated has increased. Similar molecular subtypes of SE are commonly isolated from humans and chickens. Conclusions. Most SE infections in the United States are acquired from domestic sources, and the problem is growing. Chicken and eggs are likely major sources of SE. Continued close attention to surveillance data is needed to monitor the impact of recent regulatory control measures

Risk Factors for Non-O157 Shiga Toxin–Producing Escherichia coli Infections, United States

Shiga toxin–producing Escherichia coli (STEC) causes acute diarrheal illness. To determine risk factors for non-O157 STEC infection, we enrolled 939 patients and 2,464 healthy controls in a case–control study conducted in 10 US sites. The highest population-attributable fractions for domestically acquired infections were for eating lettuce (39%), tomatoes (21%), or at a fast-food restaurant (23%). Exposures with 10%–19% population attributable fractions included eating at a table service restaurant, eating watermelon, eating chicken, pork, beef, or iceberg lettuce prepared in a restaurant, eating exotic fruit, taking acid-reducing medication, and living or working on or visiting a farm. Significant exposures with high individual-level risk (odds ratio >10) among those >1 year of age who did not travel internationally were all from farm animal environments. To markedly decrease the number of STEC-related illnesses, prevention measures should focus on decreasing contamination of produce and improving the safety of foods prepared in restaurants