An outbreak of multiple serotypes of salmonella in New Zealand linked to consumption of contaminated tahini imported from Turkey.

A widespread salmonellosis outbreak linked to consumption of hummus made from contaminated tahini imported from Turkey occurred in New Zealand in November 2012. This article summarizes the outbreak detection, investigation, and control. The New Zealand Enteric Reference Laboratory alerted public health units regarding a cluster of 11 persons with Salmonella Montevideo infection identified from different regions of the North Island of New Zealand. A multiagency outbreak investigation commenced to determine the source of illness and prevent further transmission. Salmonellosis is a notifiable disease in New Zealand. Outbreak cases were identified through routine salmonellosis notifications, and interviewed using a standardized questionnaire to identify common exposures. Clinical and food isolates were initially characterized by serotyping and then further typed by pulsed-field gel electrophoresis (PFGE). PFGE profiles were sent to PulseNet and international alerts were posted. The scope of the investigation widened to include persons with either Salmonella Maastricht and Salmonella Mbandaka infection following detection of these serotypes in tahini epidemiologically linked to laboratory-confirmed cases. All three of the tahini-associated serotypes were detected in people who had consumed tahini, and these were found to have PFGE profiles indistinguishable from the tahini isolates. Twenty-seven salmonellosis cases infected with at least one of the three tahini-associated Salmonella serotypes were detected between September 1 and December 31, 2012; of these, 16 (59%) cases (12 with Salmonella Montevideo, 3 with Salmonella Mbandaka, and 1 with Salmonella Maastricht infection) had PFGE patterns indistinguishable from the outbreak profile. The investigation led to a trade withdrawal and consumer recall for tahini sesame paste from the consignment and products containing this tahini. The outbreak ceased following the recall. The importer of the implicated tahini was reminded of his duties as a food importer, including ensuring appropriate product testing. Changes to New Zealand legislation strengthened food safety responsibilities of food importers.

An outbreak of Salmonella Typhimurium phage type 42 associated with the consumption of raw flour.

A cluster of salmonellosis cases caused by Salmonella Typhimurium phage type 42 (STM42) emerged in New Zealand in October 2008. STM42 isolates from a wheat-based poultry feed raw material (broll; i.e., product containing wheat flour and particles of grain) had been identified in the 2 months prior to this cluster. Initial investigations indicated that eating uncooked baking mixture was associated with illness. A case-control study was conducted to test the hypothesis that there was an association between STM42 cases and consumption of raw flour or other baking ingredients. Salmonella isolates from human and non-human sources were compared using pulsed-field gel electrophoresis (PFGE) and multiple-locus variable number tandem repeat analysis (MLVA). Environmental investigations included testing flour and other baking ingredients from case homes, unopened bags of flour purchased from retail stores, and inspection of an implicated flour mill. A case-control study of 39 cases and 66 controls found cases had 4.5 times the odds of consuming uncooked baking mixture as controls (95% confidence interval [CI] 1.6-12.5, p-value 0.001). Examination of individual baking ingredients found that, after adjusting for eggs, flour had an odds ratio (OR) of 5.7 (95% CI 1.1-29.1, p-value 0.035). After adjusting for flour, eggs had an OR of 0.8 (95% CI 0.2-3.4, p-value 0.762). PFGE patterns were identical for all STM42 isolates tested; however, MLVA distinguished isolates that were epidemiologically linked to the cluster. STM42 was recovered from flour taken from four cases' homes, two unopened packs purchased from retail stores and packs from three batches of retrieved (recalled) product. This outbreak was associated with the consumption of uncooked baking mixture containing flour contaminated with STM42. The implicated flour mill initiated a voluntary withdrawal from sale of all batches of flour thought to be contaminated. Media releases informed the public about implicated flour brands and the risks of consuming uncooked baking mixture.

A large scale waterborne Campylobacteriosis outbreak, Havelock North, New Zealand.

BACKGROUND: We describe the investigation of a Campylobacter outbreak linked to contamination of an untreated, groundwater derived drinking water supply. METHODS: We analysed epidemiological data collected from clinician-confirmed diarrheal cases and estimated the total burden of Havelock North cases using an age-adjusted cross-sectional telephone survey. Campylobacter isolates from case fecal specimens, groundwater samples, and sheep fecal specimens from paddocks adjacent to the drinking water source were whole genome sequenced. FINDINGS: We estimate between 6260 and 8320 cases of illness including up to 2230 who lived outside the reticulation area, were linked to the contaminated water supply. Of these, 953 cases were physician reported, 42 were hospitalized, three developed Guillain-Barré syndrome, and Campylobacter infection contributed to at least four deaths. Of the 12 genotypes observed in cases, four were also observed in water, three were also observed in sheep and one was also observed in both water and sheep. INTERPRETATION: The contamination of the untreated reticulated water supply occurred following a very heavy rainfall event which caused drainage of sheep feces into a shallow aquifer. The existence of a routine clinical surveillance system for campylobacteriosis facilitated identification of the outbreak, recovery of clinical isolates, and early testing of the water for pathogens. Genotyping of the Campylobacter jejuni helped define the source of the outbreak and confirm outbreak periods and cases. Expected increases in heavy rainfall events and intensification of agriculture mean that additional safeguards are needed to protect populations from such drinking water outbreaks. FUNDING: NZ Ministry of Health, Health Research Council, ESR SSIF, Royal Society.