Novel application of the matched case-control design to compare food supply chains during an Escherichia coli O157 outbreak, United Kingdom, 2016.

There is a need for innovative methods to investigate outbreaks of food-borne infection linked to produce with a complex distribution network. The investigation of a large outbreak of Escherichia coli O157 PT34 infection in the United Kingdom in 2016 indicated that catering venues associated with multiple cases had used salad leaves sourced from one supplier. Our aim was to investigate whether catering venues linked to cases were more likely to have used salad leaves from this supplier. We conducted a matched case-control study, with catering venues as the units of analysis. We compared venues linked to cases to those without known linked cases. We included 43 study pairs and obtained information on salad leaf products received by each venue. The odds of a case venue being supplied with salad leaves by Supplier A were 7.67 times (95% confidence interval: 2.30-25.53) those of control venues. This association provided statistical evidence to support the findings of the other epidemiological investigations undertaken for this outbreak. This is a novel approach which is labour-intensive but which addresses the challenge of investigating exposures to food across a complex distribution network.

A model to assess the efficacy of vaccines for control of liver fluke infection.

Fasciola hepatica, common liver fluke, infects cattle and sheep causing disease and production losses costing approximately $3 billion annually. Current control relies on drugs designed to kill the parasite. However, resistance is evident worldwide and widespread in some areas. Work towards a vaccine has identified several antigens of F. hepatica that show partial efficacy in terms of reducing worm burden and egg output. A critical question is what level of efficacy is required for such a vaccine to be useful? We have created the first mathematical model to assess the effectiveness of liver fluke vaccines under simulated field conditions. The model describes development of fluke within a group of animals and includes heterogeneity in host susceptibility, seasonal exposure to metacercariae and seasonal changes in temperature affecting metacercarial survival. Our analysis suggests that the potential vaccine candidates could reduce total fluke burden and egg output by up to 43% and 99%, respectively, on average under field conditions. It also suggests that for a vaccine to be effective, it must protect at least 90% of animals for the whole season. In conclusion, novel, partial, vaccines could contribute substantially towards fasciolosis control, reducing usage of anthelmintics and thus delaying the spread of anthelmintic resistance.

Botulinum toxin A for treatment of sialorrhea in children: an effective, minimally invasive approach.

OBJECTIVES: To report (1) our experience with botulinum toxin A injections into the salivary glands of pediatric patients with sialorrhea, (2) the clinical outcomes of these interventions, and (3) the associated complication rates. DESIGN: Retrospective cohort study. SETTING: Urban pediatric hospital and pediatric rehabilitation center. PATIENTS: Forty-five neurologically impaired children. INTERVENTIONS: Patients received botulinum toxin A intrasalivary injections between January 2004 and May 2008 at the Hospital for Sick Children in Toronto, Ontario, Canada. All patients received sedation or general anesthesia for their botulinum toxin A injections, which were performed using ultrasonographic guidance. MAIN OUTCOME MEASURES: Posttreatment assessments included the duration of effect, patient complications, saliva consistency, caregiver willingness to repeat the treatment, caregiver satisfaction with the treatment, and caregiver overall assessment of the child's posttreatment quality of life. RESULTS: Forty-five subjects received a total of 91 botulinum toxin A treatments. The mean (SD) duration of effect was 4.6 (5.2) months. Duration of effect (log transformed) was significantly negatively associated with saliva quantity (P = .02), and there was a positive association with both increasing age and female sex, although neither reached statistical significance (P = .08 for each). Seven of the 24 documented complications were major, according to the Society of Interventional Radiology Classification System for Complications by Outcome scale. Thirty-six of the caregivers reported that this treatment improved the child's quality of life (80%). CONCLUSION: Ultrasonographically guided botulinum toxin A injections into the salivary glands are safe and efficacious in the management of sialorrhea in children with neurologic disorders.