Human Salmonella isolates for 2023

The number of Salmonella isolates confirmed this year (n=833) showed an increase in comparison with 2022 (n= 738). Salmonella Typhimurium ST19 was the predominant serotype, representing 20.2% of total isolates.

Salmonella serotypes showing an increase this year in comparison with 2022 included: Salmonella Agona (from 1.4% to 2.3%), Salmonella Chester (from 0.1% to 1.9%), Salmonella Derby (from 0.0% to 0.4%), Salmonella Paratyphi A (from 1.8% to 3%), Salmonella Paratyphi B var. Java (from 0.7% to 3.4%), Salmonella Typhi (from 3.9% to 8.3%) and Salmonella Weltevreden (from 0.8% to 2.8%).

Salmonella serotypes showing a decrease this year in comparison with 2022 included: Salmonella Bovismorbificans (from 6.2% to 3.1%), Salmonella Give (from 1.3% to 0.5%) and Salmonella Kintambo (from 0.9% to 0.2%).

• An outbreak of typhoid fever among rural workers in Tairawhiti district was investigated by Te Manawa Taki.  The outbreak began after a team member had returned from overseas, In total 12 cases were identified among the workers who lived in shared accommodation.

The number of isolates (n=99) confirmed this month showed an increase in comparison to the number of isolates confirmed in January 2028 (n=64). Salmonella Typhimurium ST19 (20.3% in 2022 vs 27.3% in 2023) was the most common serotypes confirmed this month. Uncommon serotype confirmed this month was Salmonella Johannesburg (16 human cases since it was first confirmed in New Zealand in 1990), Salmonella Kiambu (25 human cases since it was first confirmed in New Zealand in 1990), Salmonella Orion (15 human cases since it was first confirmed in New Zealand in 1993), Salmonella Poona (42 human cases since it was first confirmed in New Zealand in 1998), Salmonella Ruiru (20 human cases since it was first confirmed in New Zealand in 2004) and Salmonella Sandiego (47 human cases since it was first confirmed in New Zealand in 1992).

The number of isolates (n=96) confirmed this month showed an increase in comparison to the number of isolates confirmed in February 2022 (n=72). Salmonella Typhimurium ST19 (26.3% in 2022 vs 26% in 2023) was the most common serotypes confirmed this month. Uncommon Salmonella serotypes confirmed this month were S. Kintambo (8 human isolates since it was first confirmed in New Zealand in 2022)

The number of isolates (n=100) confirmed this month showed a decrease in comparison to the number of isolates confirmed in March 2022 (n=100). Salmonella Typhimurium ST19 (35.6% in 2022 vs 26% in 2023) was the most common serotypes confirmed this month. Uncommon serotype confirmed this month was Salmonella Uganda (22 human cases since it was first confirmed in New Zealand in 1994).

The number of isolates (n=54) confirmed this month showed a decrease in comparison to the number of isolates confirmed in April 2022 (n=74). Salmonella Typhimurium ST19 (45.9% in April 2022 vs 27.8% in April 2023) was the most common type confirmed this month. Uncommon serotypes confirmed this month was Salmonella Kedougou (15 human cases since it was first confirmed in New Zealand in 1996) and Salmonella Muenster (13 human cases since it was first confirmed in New Zealand in 1994).An isolate was typed as Subsp. (I) ser. 9,12 : m,p : - ST74. This is the first incidence of this isolate in New Zealand. This sequence type has been associated with S. Enteritidis and S. Dublin but has been found to be a novel serotype. Awaiting serotype designation by Institut Pasteur and WHO.

The number of isolates (n=79) confirmed this month showed an increase in comparison to the number of isolates confirmed in May 2022 (n=61). Salmonella Typhimurium ST19 (26.2% in May 2022 vs 16.5% in May 2023) was the most common type confirmed this month. Uncommon serotype confirmed this month was Salmonella Goldcoast (3 human cases since it was first confirmed in New Zealand in 1989).

The number of isolates (n=68) confirmed this month showed a slight increase in comparison to the number of isolates confirmed in June 2022 (n=54). Salmonella Typhimurium ST19 (20.4% in June 2022 vs 19.1% in June 2023) was the most common serotype confirmed this month.

The total number of isolates (n=40) confirmed this month showed a slight decrease in comparison to the number of isolates confirmed in July 2022 (n=45). Salmonella Agona, Salmonella Brandenburg, Salmonella Enteritidis ST11, Salmonella Monophasic Typhimurium ST34, and Salmonella Typhimurium ST568 (2.2%, 2.2%, 2.2%, 0% and 24.4%, respectively, in July 2022 vs. 7.5% in July 2023) were the most common serotypes confirmed this month. 

The number of isolates (n=65) confirmed this month showed a decrease in comparison to the number of isolates confirmed in August 2022 (n=74). Salmonella Typhimurium ST19 (35.1% in August 2022 vs 12.3% in August 2023) was the most common serotype confirmed this month. Uncommon serotypes confirmed this month was Salmonella Choleraesuis var. Kunzendorf (9 human cases since it was first confirmed in New Zealand in 1989) and Salmonella Kintambo (9 human cases since it was first confirmed in New Zealand in 2022). 

The number of isolates (n=58) confirmed this month showed a slight increase in comparison to the number of isolates confirmed in September 2022 (n=57). Salmonella Typhimurium ST19 (21% in September 2022 vs. 17.2% in September 2023) was the most common serotype confirmed this month. Uncommon serotypes confirmed this month were Salmonella Isangi (18 human cases since it was first confirmed in New Zealand in 1990) and Salmonella Matopeni (2 human cases since it was first confirmed in New Zealand in 1995). An outbreak of typhoid fever among RSE workers in Tairawhiti. Tairawhiti PHU investigated an outbreak of typhoid fever involving 8 cases (6 confirmed in September). The cases are all RSE workers who live in shared accommodation. The most likely source of the outbreak was an RSE worker who does all the cooking for the group and recently travelled overseas.

The number of isolates (n=66) confirmed this month showed an increase in comparison to the number of isolates confirmed in October 2022 (n=61). Salmonella Typhimurium ST19 (19.7% in October 2022 vs. 15.2% in October 2023) was the most common serotype confirmed this month. An outbreak of typhoid fever among RSE workers in Tairawhiti. Tairawhiti PHU investigated an outbreak of typhoid fever involving 8 cases (2 confirmed in October). The cases are all RSE workers who live in shared accommodation. The most likely source of the outbreak was an RSE worker who does all the cooking for the group and recently travelled overseas.

The number of isolates (n=66) confirmed this month showed a decrease in comparison to the number of isolates confirmed in November 2022 (n=75). Salmonella Typhimurium ST19 (28% in November 2022 vs. 19.7% in November 2023) was the most common serotype confirmed this month. 

The number of isolates (n=42) confirmed this month showed an increase in comparison to the number of isolates confirmed in December 2022 (n=56). Salmonella Typhimurium ST19 (17.8% in December 2022 vs 14.3% in December 2023) was the most common serotypes confirmed this month. Uncommon Salmonella serotypes confirmed this month were S. Chailey (8 human isolates since it was first confirmed in New Zealand in 1992) and S. Coeln (3 human isolates since it was first confirmed in New Zealand in 2017).