Human salmonella isolates 2015

Annual summary 2015

The number of Salmonella isolates confirmed this year (n=1133) showed an increase in comparison with 2014 (n= 1022). Salmonella Typhimurium phage type 56 variant remained the predominant serotype, representing 8.5% of total isolates (7.1% in 2014). Salmonella serotypes showing an increase this year in comparison with 2014 included: S. Bovismorbificans (from 0.4% to 2.0%), S. Brandenburg (from 3.4% to 4.6%), S. Thompson (from 0.5% to 2.8%), S. Typhimurium phage type 135 (from 3.4% to 5.7%) and phage type 156 (from 0.9% to 2.4).

Significant outbreaks and clusters:

Outbreak of S. Thompson linked to food premises in Northland (Source: Health Intelligence Team, EpiSurv, ERL, Northland DHB, ARPHS, MPI)

• During the month of January, there were 24 laboratory confirmed cases of S. Thompson reported from Auckland (8 cases), Northland and Waitemata (7 cases each), Counties Manukau and Capital and Coast (1 case each) DHBs. This is an increase for the region when compared to previous years (no cases in 2014, 4 cases in 2013, no cases in 2012).
• At least 16 cases (Auckland region 11 cases, Northland DHB 4 cases and Capital and Coast DHB 1 case) were known to have consumed food from a bakery in Northland during the incubation period. The most common foods consumed include lamb and salad focaccia/rolls (9 cases) and chicken and salad rolls/sandwich (4 cases).
• Molecular typing using Pulsed-Field Gel Electrophoresis (PFGE) was done on a selection of the case isolates and all cases shared an indistinguishable profile. This suggests that cases were exposed to the common source of infection.

Increase in S. Typhimurium phage type 101(Source: EpiSurv, ERL)

• From 01 Feb to 01 April 2015 there were 22 cases of S. Typhimurium phage type 101 reported to EpiSurv. This was an increase compared to the same period in previous years (9 in 2014, 7 in 2013 and 8 in 2012).
• Cases were reported from the following DHBs: Canterbury (15 cases compared to 3 in 2014, 3 in 2013 and 4 in 2012), Waitemata (5 cases compared to 3 in 2014, 2 in 2013 and 0 in 2012), Southern and Whanganui (1 case each).
• No common exposures were identified from EpiSurv data. No cases were known to have travelled overseas during the incubation period (travel history was known for 11 cases).

Increase in S. Enteritidis phage type 11 (Source: EpiSurv, ERL)

• From 01 April to 12 May 2015 there were 14 cases of S. Enteritidis phage type 11 reported to EpiSurv. This was an increase compared to the same period in the previous two years (7 in 2014 and 1 in 2013) but similar to what was observed in 2012 (11 cases) and 2011 (12 cases). Prior to 2012 S. Enteritidis phage type 11 was known as phage type 9a.
• Cases were reported from the following DHBs: MidCentral (3 cases), Waikato and Nelson Marlborough (2 cases each), Northland, Waitemata, Bay of Plenty, Whanganui, Hutt Valley, Canterbury and Southern (1 case each).
• No common exposures were identified from EpiSurv data.