Human Salmonella Isolates, 2016

Thursday 21st September 2017


Human Salmonella Isolates, 2016

The number of Salmonella isolates confirmed this year (n=1150) showed an increase in comparison with 2015 (n= 1133). Salmonella Brandenburg was the predominant serotype, representing 5.8% of total isolates (4.6% in 2015). Salmonella serotypes showing an increase this year in comparison with 2015 included: S. Bovismorbificans (from 2.0% to 3.4%), S. Brandenburg (from 4.6% to 5.8%) and S. Stanley (from 2.2% to 5.2%).

Significant outbreaks and clusters:

Increase in Salmonella Typhimurium phage type 9 notifications November 2015 to April 2016 (Source: Health Intelligence Team, EpiSurv, ERL)

• From 01 November 2015 to 12 April 2016 there have been 40 notifications of Salmonella Typhimurium phage type 9 in New Zealand. This is a significant increase when compared to the same period in previous years (10 in 2014/2015, 8 in 2013/2014).
• The largest number of cases have been reported from the following DHBs: Tairawhiti (14 cases compared to 1 in 2014/2015 and 2 in 2013/2014), Southern (6 cases compared to 1 in 2014/2015 and 2 in 2013/2014), Waitemata (5 cases) and Auckland (4 cases).
• Cases range in age from 11 months to 82 years, with the majority of cases (28 cases, 70.0%) being adults aged 20 years and older. Sex is evenly distributed.
• 11 cases (35.5%) were hospitalised (31 had a known hospitalisation history).
• The most common risk factors recorded in EpiSurv were contact with faecal matter (38.1%, 8/21), consumption of untreated water (33.3%, 8/24 cases), eating food from a food premise (30.4%, 7/23 cases), recreational water contact (30.4%, 7/23 cases) and contact with farm animals (20.0%, 5/25 cases).
• Multiple-Locus Variable-number tandem repeat Analysis (MLVA) results show 15 different profiles with 17 cases having an identical profile (EU profile 2-20-3-11-0211). Cases with this profile are widely distributed in the North Island (Tairawhiti: 6 cases, Waitemata: 5 cases, Waikato and Hawke’s Bay: 2 cases each, Auckland and Capital and Coast: 1 case each).
• The ERL has confirmed this phage type in isolates from bovine, ovine, food (not specified) and poultry environment sources previously.

Increase in Salmonella Stanley notifications reported to Tairawhiti DHB in February-May 2016 (Source: Health Intelligence Team, EpiSurv, Tairawhiti DHB, ERL, MPI, Ministry of Health)

• Tairawhiti DHB, in conjunction with the Ministry of Health, Ministry for Primary Industries and ESR, are investigating an increase in Salmonella Stanley notifications. From 01 February to 04 May 2016 there have been 14 cases reported, a significant increase compared to the same period in previous years (no cases reported previously).
• None of the 14 cases had travelled overseas during the incubation period. In 2015 there were 26 cases of S. Stanley reported in New Zealand, of which 87.0% (20 of the 23 cases with known travel history) were overseas acquired infections.
• Cases are adults ranging in age from 24 to 86 years with the exception of one case who is 2 years old and most likely a secondary case. Sex of cases is evenly distributed.
• Pulsed-Field Gel Electrophoresis (PFGE) was performed on a selection of case isolates of S. Stanley confirmed this year and included 10 from Tairawhiti DHB. A common profile, and a profile with one band difference was identified among the Gisborne cluster which suggests that cases may have been exposed to the same source of infection. One case from Auckland DHB was also found to have the outbreak profile. This case has confirmed they were in Gisborne during the incubation period. All other cases had PFGE profiles distinguishable from the outbreak cluster.

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Human Salmonella isolates, 2016

 

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Human Salmonella isolates, 2016

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