Human Salmonella Isolates, 2015 No. 1, January

The number of isolates (n=160) confirmed this month showed an increase in comparison to the number of isolates confirmed in January 2014 (n=143). Salmonella Thompson was the most common serotype confirmed this month due to an outbreak in the upper North Island (0.7% in January 2014, 15% in January 2015). Uncommon Salmonella serotypes confirmed this month included: S. Adelaide (8 human cases since it was first confirmed in 1992), S. Enteritidis phage type 20 (5 human cases since it was first confirmed in 1997), S. Glodstrup (1 human case since it was first confirmed in 2010), and S. Typhimurium phage type U307 (7 human cases since it was first confirmed in 2010, six of whom were confirmed in December 2014). Salmonella Enteritidis phage type 55 was confirmed for the first time in New Zealand, the case had recently travelled to Taiwan.

Cluster of S. Bovismorbificans

• Four cases of S. Bovismorbificans were confirmed in the Auckland region this month.

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) are 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 same source of infection.