Bi-national outbreak of Salmonella Newport infections linked to onions: the United States experience.

From 2016-2019, dry bulb onions were the suspected cause of three multistate outbreaks in the United States. We investigated a large multistate outbreak of Salmonella Newport infections that caused illnesses in both the United States and Canada in 2020. Epidemiologic, laboratory and traceback investigations were conducted to determine the source of the infections, and data were shared among U.S. and Canadian public health officials. We identified 1127 U.S. illnesses from 48 states with illness onset dates ranging from 19 June to 11 September 2020. Sixty-six per cent of ill people reported consuming red onions in the week before illness onset. Thirty-five illness sub-clusters were identified during the investigation and seventy-four per cent of sub-clusters served red onions to customers during the exposure period. Traceback for the source of onions in illness sub-clusters identified a common onion grower in Bakersfield, CA as the source of red onions, and onions were recalled at this time. Although other strains of Salmonella Newport were identified in environmental samples collected at the Bakersfield, CA grower, extensive environmental and product testing did not yield the outbreak strain. This was the third largest U.S. foodborne Salmonella outbreak in the last 30 years. It is the first U.S. multistate outbreak with a confirmed link to dry bulb onions, and it was nearly 10-fold larger than prior outbreaks with a suspected link to onions. This outbreak is notable for its size and scope, as well as the international data sharing that led to implication of red onions as the primary cause of the outbreak. Although an environmental assessment at the grower identified several factors that likely contributed to the outbreak, no main reason was identified. The expedient identification of the outbreak vehicle and response of multiple public health agencies allowed for recall and removal of product from the marketplace, and rapid messaging to both the public and industry on actions to protect consumers; these features contributed to a decrease in cases and expeditious conclusion of the outbreak.

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.

Public health investigation and response to a hepatitis A outbreak from imported scallops consumed raw-Hawaii, 2016.

During the summer of 2016, the Hawaii Department of Health responded to the second-largest domestic foodborne hepatitis A virus (HAV) outbreak in the post-vaccine era. The epidemiological investigation included case finding and investigation, sequencing of RNA positive clinical specimens, product trace-back and virologic testing and sequencing of HAV RNA from the product. Additionally, an online survey open to all Hawaii residents was conducted to estimate baseline commercial food consumption. We identified 292 confirmed HAV cases, of whom 11 (4%) were possible secondary cases. Seventy-four (25%) were hospitalised and there were two deaths. Among all cases, 94% reported eating at Oahu or Kauai Island branches of Restaurant Chain A, with 86% of those cases reporting raw scallop consumption. In contrast, a food consumption survey conducted during the outbreak indicated 25% of Oahu residents patronised Restaurant Chain A in the 7 weeks before the survey. Product trace-back revealed a single distributor that supplied scallops imported from the Philippines to Restaurant Chain A. Recovery, amplification and sequence comparison of HAV recovered from scallops revealed viral sequences matching those from case-patients. Removal of product from implicated restaurants and vaccination of those potentially exposed led to the cessation of the outbreak. This outbreak further highlights the need for improved imported food safety.

Unusually high illness severity and short incubation periods in two foodborne outbreaks of Salmonella Heidelberg infections with potential coincident Staphylococcus aureus intoxication.

We describe the investigation of two temporally coincident illness clusters involving salmonella and Staphylococcus aureus in two states. Cases were defined as gastrointestinal illness following two meal events. Investigators interviewed ill persons. Stool, food and environmental samples underwent pathogen testing. Alabama: Eighty cases were identified. Median time from meal to illness was 5·8 h. Salmonella Heidelberg was identified from 27 of 28 stool specimens tested, and coagulase-positive S. aureus was isolated from three of 16 ill persons. Environmental investigation indicated that food handling deficiencies occurred. Colorado: Seven cases were identified. Median time from meal to illness was 4·5 h. Five persons were hospitalised, four of whom were admitted to the intensive care unit. Salmonella Heidelberg was identified in six of seven stool specimens and coagulase-positive S. aureus in three of six tested. No single food item was implicated in either outbreak. These two outbreaks were linked to infection with Salmonella Heidelberg, but additional factors, such as dual aetiology that included S. aureus or the dose of salmonella ingested may have contributed to the short incubation periods and high illness severity. The outbreaks underscore the importance of measures to prevent foodborne illness through appropriate washing, handling, preparation and storage of food.

International outbreak of multiple Salmonella serotype infections linked to sprouted chia seed powder - USA and Canada, 2013-2014.

Salmonella is a leading cause of bacterial foodborne illness. We report the collaborative investigative efforts of US and Canadian public health officials during the 2013-2014 international outbreak of multiple Salmonella serotype infections linked to sprouted chia seed powder. The investigation included open-ended interviews of ill persons, traceback, product testing, facility inspections, and trace forward. Ninety-four persons infected with outbreak strains from 16 states and four provinces were identified; 21% were hospitalized and none died. Fifty-four (96%) of 56 persons who consumed chia seed powder, reported 13 different brands that traced back to a single Canadian firm, distributed by four US and eight Canadian companies. Laboratory testing yielded outbreak strains from leftover and intact product. Contaminated product was recalled. Although chia seed powder is a novel outbreak vehicle, sprouted seeds are recognized as an important cause of foodborne illness; firms should follow available guidance to reduce the risk of bacterial contamination during sprouting.

2013 multistate outbreaks of Cyclospora cayetanensis infections associated with fresh produce: focus on the Texas investigations.

The 2013 multistate outbreaks contributed to the largest annual number of reported US cases of cyclosporiasis since 1997. In this paper we focus on investigations in Texas. We defined an outbreak-associated case as laboratory-confirmed cyclosporiasis in a person with illness onset between 1 June and 31 August 2013, with no history of international travel in the previous 14 days. Epidemiological, environmental, and traceback investigations were conducted. Of the 631 cases reported in the multistate outbreaks, Texas reported the greatest number of cases, 270 (43%). More than 70 clusters were identified in Texas, four of which were further investigated. One restaurant-associated cluster of 25 case-patients was selected for a case-control study. Consumption of cilantro was most strongly associated with illness on meal date-matched analysis (matched odds ratio 19·8, 95% confidence interval 4·0-∞). All case-patients in the other three clusters investigated also ate cilantro. Traceback investigations converged on three suppliers in Puebla, Mexico. Cilantro was the vehicle of infection in the four clusters investigated; the temporal association of these clusters with the large overall increase in cyclosporiasis cases in Texas suggests cilantro was the vehicle of infection for many other cases. However, the paucity of epidemiological and traceback information does not allow for a conclusive determination; moreover, molecular epidemiological tools for cyclosporiasis that could provide more definitive linkage between case clusters are needed.

Comparing Visual and Digital Counting Methods to Estimate Horn Fly (Diptera: Muscidae) Populations on Cattle.

Horn fly, Haematobia irritans (L.), population estimates often serve as a diagnostic tool prior to implementing managerial control options available to researchers and producers. Digital photographs taken of cattle infested with horn flies have been suggested to provide similarly accurate population estimates as compared with traditional visual assessments. The objective of this study was to compare visual and digital techniques used to estimate horn fly populations. Sixteen Angus × Hereford yearling heifers artificially infested with four levels of horn flies (Low = 0 flies; Medium = 250 flies; High = 500 flies; Extreme = 1,000 flies) were evaluated. Population estimates were taken visually by experienced (VE1) and inexperienced (VE2) technicians, as well as digitally, with photographs taken on both lateral sides of the south-facing animal. Horn flies were counted in both photographs and combined (CDC) for full body estimates. In addition, the highest photographed side population times two (DDC) was used for comparison. Estimations were made at 0700, 1200, and 1900 h the day following infestation. A time of observation × infestation level interaction (P < 0.01) was detected. On average, VE1 population estimates were greater (P < 0.01) than any other counting method observed. Morning estimates were greater (P < 0.05) than those taken at noon or in the early evening regardless of counting method. Further research regarding the standardization of these techniques to ensure more accurate population estimates is needed before these methods can be incorporated into integrated pest management programs.

Random walk type models for indicator-dilution studies: comparison of a local density random walk and a first passage times distribution.

The relative merits of the local density random walk and the first passage times distributions were compared with respect to their practical applicability in cardiovascular research and clinical practice. Open indicator-dilution curves of varying shape were used, and reference values for area and mean transit times were calculated numerically. Curves not perturbed by recirculation were obtained in two different ways. Thermodilution curves were obtained in an animal model at the left and the right side of the heart respectively and conductivity curves with 0.5% NaCl solution as indicator were obtained in a hydrodynamic circulation model. The fits of the two types of distribution were equally accurate for the more symmetrical curves; for very skewed curves the local density random walk fit proved to be more accurate. This result could be related to the greater difference in shape between the first passage times and local density random walk distribution for a large degree of asymmetry. For this reason the local density random walk distribution for fitting indicator-dilution curves was used in a variety of other experimental conditions.

Are psychiatrists only fools and horses to be open all hours?

The UK government's proposal for 24-hour healthcare means effectively asking doctors to work more unsociable hours for relatively little financial gain. In our opinion, psychiatry is particularly vulnerable to deterioration owing to negotiations of the terms of the current Consultant Contract that ensures fewer antisocial hours, whereas without parallel appropriate internal team and intra-agency working, provisions for which are not included in the government's proposals to extend care, patient care is vulnerable. Clarification and a narrower redefinition of what constitutes a psychiatric emergency is called for.

Ontogeny of pulsatile secretion of gonadotropin-releasing hormone in the bull calf during infantile and pubertal development.

During the infantile period of development in the bull calf (birth to 6 weeks of age), there is a virtual absence of episodic secretion of LH. Transition from infancy to the prepubertal period (6-10 weeks of age) is characterized by the onset of episodic LH release. This study was conducted to characterize the ontogeny of episodic GnRH release during these developmental periods. During the primary experiment, calves at 2, 5, 8, and 12 weeks of age (n = 4/age) were surgically fitted with cannulae for the collection of mixed hypophyseal portal and cavernous sinus blood. Hypophyseal portal and cavernous sinus and jugular blood samples were collected over a 9- to 12-h period at 10 min intervals. No pulses of LH were observed in calves at 2 or 5 weeks of age. At 8 and 12 weeks of age, pulsatile LH release became evident with a mean of 1.0 +/- 0.3 and 2.20 +/- 0.7 pulses/10 h, respectively. Unlike LH secretion, calves at both 2 and 5 weeks of age released GnRH in a pulsatile manner (3.5 +/- 0.2 and 5.0 +/- 0.6 pulses/10 h, respectively). The frequency of pulsatile GnRH release increased from 7.9 +/- 0.4 pulses/10 h at 8 weeks of age to 8.9 +/- 0.7 pulses/10 h at 12 weeks of age. These findings demonstrate the presence of pulsatile secretion of GnRH during the infantile period of development. Furthermore, the postnatal ontogeny of pulsatile LH release in this species is associated with an increase in the frequency of pulsatile GnRH secretion.

Prostaglandin F2 alpha-induced calcium transient in ovine large luteal cells: I. Alterations in cytosolic-free calcium levels and calcium flux.

The effect of prostaglandin F2 alpha (PGF2 alpha) on cytosolic calcium homeostasis was studied in suspensions of ovine large or small luteal cells from superovulated ewes. In large cells loaded with fura-2 (AM), resting cytosolic-free calcium ([Ca2+]i) was 62 +/- 5 nM (Hanks' medium, pH 7.15), and PGF2 alpha (0.5 microM) induced a rapid transient increase in [Ca2+]i to 152 +/- 6 nM, which then decreased to 97 +/- 6 nM within 3 min and remained at this level for the remainder of the treatment period (10-20 min). PGF2 alpha did not alter intracellular pH (pHi) in cells loaded with snarf-1 (AM) (pHi indicator). The transient nature of the [Ca2+]i increase was due, at least in part, to the ability of PGF2 alpha to stimulate (P less than 0.05) 45Ca2+ efflux. In small cells, resting [Ca2+]i was 57 +/- 5 nM, and no change in [Ca2+]i levels or pHi occurred with the addition of PGF2 alpha. PGF2 alpha also did not affect 45Ca2+ efflux in small cells. Calcium uptake was not significantly altered by PGF2 alpha in large or small cells. Data from kinetic analysis of the calcium transient was best fit to a two-compartment model consisting of a rapidly effluxing compartment and a slowly effluxing compartment. The size and rate constants were 62 +/- 10 nM and 3.6 +/- 1 min-1, respectively, for the rapidly effluxing compartment and 140 +/- 9 nM and 0.02 +/- 0.002 min-1, respectively, for the slowly effluxing compartment. These results provide evidence for a direct effect of PGF2 alpha specifically on the ovine large luteal cell that involves alterations in [Ca2+]i and calcium flux. This effect is likely to be involved in intracellular mediation of the signal for luteal regression.

Pineal melatonin inhibition of tumor promotion in the N-nitroso-N-methylurea model of mammary carcinogenesis: potential involvement of antiestrogenic mechanisms in vivo.

The N-methyl-N-nitrosourea (NMU) model of hormone-responsive rat mammary carcinogenesis was used to address the hypothesis that melatonin (Mel), the principle hormone of the pineal gland, inhibits tumorigenesis by acting as an anti-promoting rather than an anti-initiating agent. Daily late-afternoon injections of Mel (500 micrograms/day), restricted to the initiation phase of NMU mammary tumorigenesis, were ineffective in altering tumor growth over a 20-week period. When Mel treatment was delayed for 4 weeks after NMU and then continued through the remainder of the promotion phase, only tumor number was significantly lower than in controls. However, when Mel injections encompassed the entire promotion phase, both tumor incidence and number were significantly lower than in the controls. Although elimination of the endogenous Mel signal via pinealectomy promoted tumor growth, the effect was not statistically significant. Serum levels of estradiol and tumor estrogen receptor content were unaltered by either Mel or pinealectomy. While Mel treatment failed to affect circulating prolactin levels, pinealectomy caused a two-fold increase in serum prolactin. The estradiol-stimulated recrudescence of tumors following ovariectomy was completely blocked by either 20, 100 or 500 micrograms Mel/day or tamoxifen (20 micrograms/day). Thus, Mel appears to be an anti-promoting hormone that may antagonize the tumor-promoting actions of estradiol in this model of mammary tumorigenesis.

Chronic lateral ventricle infusion of a pineal gland-derived decapeptide alters pulsatile secretion of LH in rats.

The object of this investigation was to determine whether chronic lateral ventricle infusion of a pineal gland-derived antigonadotropic decapeptide (AGD) would affect pulsatile luteinizing hormone (LH) release in conscious, unrestrained male rats. Adult male Harlan SD rats were bilaterally orchiectomized and maintained under conditions of controlled photoperiods and temperature. After three (Experiment one) or four (Experiment two) weeks each was fitted stereotaxically with a stainless steel cannula for infusion into the right lateral ventricle. Each cannula was attached to a subcutaneous osmotic minipump filled either with artificial cerebrospinal fluid (CSF) or AGD in CSF (0.5 microgram/microliter). CSF (1.0 microliter/hr) or the AGD (0.5 microgram/microliter hr) was infused over a period of four days. Blood samples for determined of LH by radioimmunoassay were obtained at five minute intervals from a Tygon microbore cannula inserted via a femoral artery into the abdominal aorta. LH pulses were defined and identified with a computerized deconvolution algorithm designed to determine spontaneous LH secretory events. Although mean LH levels were not significantly reduced, LH secretory pulse frequency and nadirs were significantly decreased by ADG infusion (p<0.01). Additionally, LH secretory pulse amplitude and LH secretory response to LHRL administration were significantly increased (p<0.01) by AGD treatment. These results confirm initial reports of depressive effects of the AGD on LH secretion and support its hypothesized central site of action.

Gonadal regulation of LH secretion in prepubertal bull calves.

In the present study we examined the influence of castration and exogenous estradiol on pulsatile LH release during the transition from infancy to the prepubertal period of development. Bull calves were assigned to treatments (N = 5 treatment) at 6 weeks of age. Treatments consisted of intact controls, castrates and castrates receiving estradiol implants. Plasma LH response was monitored over 8 hr periods at 7, 8, 9, 10, 11 and 13 weeks of age. Castration alone did not alter LH concentrations, compared to controls until 10 weeks of age. At 10, 11 and 13 weeks, mean LH concentration and the number of LH pulses/8 hr period were greater (P less than .05) in castrates than in controls. In castrates with estradiol implants, mean LH concentration and the number of LH pulses/8 hr period were suppressed at all ages compared to controls and castrate treatments. These results indicate that LH release is not inhibited by gonadal factors from 6 to 9 weeks of age in the bull calf. However, estradiol negative feedback on LH secretion is evident during this same developmental period.

Direct effects of luteal regression on anterior pituitary response to GNRH.

The preovulatory period of the ewe is marked by a dramatic decrease in concentrations of progesterone in serum during the late luteal phase, followed by elevated luteinizing hormone (LH) secretion, final follicular maturation and ovulation. This experiment was designed to ascertain the extent to which removal of endogenous progesterone negative feedback at the anterior pituitary gland, independent of effects at the hypothalamus, promotes increased secretion of LH in the hours immediately after induction of luteolysis. Estrus was synchronized in ovary-intact ewes with two injections of prostaglandin F2 alpha (PGF2 alpha) analog given 10 d apart (Day 0 = second day after the second PGF2 alpha injection). Ewes were subjected to hypothalamic-pituitary disconnection (HPD; n = 6) on Day 3 and were pulsed with gonadotropin-releasing hormone (GnRH). Ewes were used during the estrous cycle or received approximately 400 IU pregnant mare serum gonadotropin (PMSG) on Day 2 to stimulate ovulation; there was no difference (P < 0.10) in ovulation rate or progesterone production between these two groups. Luteal regression was induced by injection of PGF2 alpha analog on approximately Day 10 of the estrous cycle. Blood samples were collected around exogenous GnRH pulses before and at 2- or 4-hr intervals after PGF2 alpha administration and concentrations of LH and progesterone determined. At 4, 12, and 24 hr after PGF2 alpha administration, mean serum progesterone levels in all ewes had decreased by 54.7%, 66.2% and 89.4%, respectively (P < 0.05) from pre-injection levels. The decrease in progesterone was associated with an increase (P < 0.01) in LH pulse amplitude with means at 4-hr post-PGF2 alpha ranging from 190% to 288% of pre PGF2 alpha values. Mean serum LH levels were also increased (P < 0.01) within 4 hr of PGF2 alpha administration and remained elevated at all but the 24-hr time point. The timing of this increase (within 4 hr) indicates that it is independent of changes in serum estradiol concentrations, which do not increase for at least 16 hr after induction of luteolysis. Thus, removal of endogenous progesterone negative feedback at the anterior pituitary gland in the hours immediately after induction of luteolysis seems to play a role in facilitating LH release independently of hypothalamic action.

Fertility and hormonal responses to temporary relief of heat stress in lactating dairy cows.

The influence of temporary cooling on pregnancy rate and ovarian secretion of cortisol, estradiol and progesterone in Holstein cows was evaluated during the months of June to September. Cows were randomly assigned to one of five treatment groups: 1) evaporative cooling, 8 d; 2) evaporative cooling, 16 d; 3) refrigerated air conditioning, 8 d; 4) refrigerated air conditioning, 16 d and 5) controls maintained outdoors with access to shade. Estrus was synchronized by giving two injections of prostaglandin (25 mg). Cows in the cooled groups were placed in box stalls at the time of the second prostaglandin injection, allowing them to be cooled for approximately 3 d prior to breeding. Blood samples were taken on days 0, 5, 10, 15, 20 and 25 postbreeding and serum was analyzed for estradiol, cortisol, progesterone and a pregnancy-specific protein. Pregnancy rates as determined by palpation per rectum at 40 to 60 d post breeding were not different between cows in cooled treatments, regardless of duration or type of cooling. Pregnancy rate was higher (P<0.05) in cooled as compared to control cows. Serum progesterone concentrations were higher on Day 15 in cooled cows as compared to control cows. No differences in serum estradiol or cortisol concentrations were observed between cooled and control cows. Pregnancy-specific protein determinations indicated that 50% of both cooled and control cows conceived. Results indicate that temporary cooling increased pregnancy rates by increasing embryonic survival rates.

Changes in the concentration of hypothalamic and hypophyseal receptors for estradiol in pregnant and postpartum ewes.

The sensitivity of the hypothalamic-pituitary axis to estradiol was evaluated by monitoring changes in the concentration of receptors for estradiol during gestation and the postpartum period of the ewe. Ewes that had been bred during anestrus so that lambing would occur during the breeding season were killed on d 50 and 140 of gestation or on d 2, 13, 22 and 35 postpartum. Total cytosolic receptors for estradiol were quantified in the anterior and posterior hypothalamus, median eminence, anterior pituitary and cerebral cortex. Concentration and total number of receptors for estradiol in the anterior and posterior hypothalamus and anterior pituitary gland during gestation through d 13 postpartum were similar but increased (P less than .05) by d 22 and 35 postpartum. Changes in the concentration of receptors for estradiol were tissue-specific because stage of reproduction did not influence the number of receptors for estradiol in the median eminence or cerebral cortex. Increases in the concentration of receptors for estradiol in hypothalamic and pituitary tissues on d 22 postpartum immediately preceded the onset of normal ovarian cyclicity in ewes. From these data we conclude that resumption of reproductive cycles in postpartum ewes occurs about the time concentrations of receptors for estradiol in the anterior pituitary gland and hypothalamus increase.