Human Salmonella isolates 2024

The number of Salmonella isolates confirmed this year (n=832) showed similar numbers in comparison with 2023 (n= 833). Salmonella Typhimurium Sequence Type (ST) 19 was the predominant serotype, representing 15% of total isolates.

Salmonella serotypes showing an increase this year in comparison with 2023 included:  Salmonella Chester (from 1.9% to 3.2%), Salmonella Enteritidis ST 11(from 6.7% to 8.2%), Salmonella Kentucky (from 0.2% to 1.1%), and Salmonella Paratyphi B var. Java (from 3.4% to 8.2%).

Salmonella serotypes showing a decrease this year in comparison with 2023 included: Salmonella Agona (from 2.3% to 1.3%), Salmonella Brandenburg (from 3.2% to 1.7%), Salmonella Enteritidis ST183 (from 4.3% to 3.1%), Salmonella Paratyphi A (from 3% to 1.6%), Salmonella Stanley (from 3.2% to 2%), and Salmonella Typhi (from 8.3% to 7.2%).

• A cluster of Salmonella Typhimurium ST2066 in the South Island. Between 22 February and 12 March 2024, 21 genomically clustered cases of Salmonella Typhimurium ST2066 were identified in the South Island. No sources were identified through the analysis of the national salmonellosis hypothesis-generating questionnaire or the investigation into the school camp outbreak.
• An increase in Salmonella Chester and Salmonella Paratyphi var. Java in travellers returning from Indonesia (Bali). Notifications of S. Chester increased in 2023 (15 cases in 2023 (including 7 with travel to Bali), compared with a pre-pandemic average of 3 cases, 2016-2019). In 2023, 20 cases of S. Paratyphi var. Java were reported (with a pre-pandemic average of 17 cases per year 2016-2019), 66% of cases had travelled to Indonesia. The majority (67%) of cases had an onset of illness prior to or on day of arrival in New Zealand. Preliminary cgMLST analysis of 26 cases of S. Chester (15 from 2023 and 9 from 2024) identified a cluster of 20 cases, 9 of which were reported in 2024 (all with travel to Indonesia). A similar analysis of S. Paratyphi var. Java cases has not identified any significant genomic clustering.

The number of isolates (n=83) confirmed this month showed a decrease in comparison to the number of isolates confirmed in January 2023 (n=99). Salmonella Typhimurium ST19 (27.3% in 2023 vs 18.1% in 2024) was the most common serotypes confirmed this month.

The number of isolates (n=86) confirmed this month showed a decrease in comparison to the number of isolates confirmed in February 2023 (n=96). Salmonella Typhimurium ST19 (26% in 2023 vs 27.9% in 2024) was the most common serotypes confirmed this month. Uncommon Salmonella serotypes confirmed this month were S. Bredeney (14 human isolates since it was first confirmed in New Zealand in 1991) and S. Butantan (4 human isolates since it was first confirmed in New Zealand in 2004)

The number of isolates (n=87) confirmed this month showed a decrease in comparison to the number of isolates confirmed in March 2023 (n=100). Salmonella Typhimurium ST2066 (0% in 2023 vs 21.8% in 2024) was the most common serotypes confirmed this month. Uncommon serotype confirmed this month was Salmonella Subsp. (IIIb) ser. 60 : r : e,n,x,z15 (3 human cases since it was first confirmed in New Zealand in 1999). Salmonella Subsp. (IIIb) ser. 61 : r : z53 was confirmed for the first time in humans in New Zealand this month.

The number of isolates (n=54) confirmed this month showed no change in comparison to the number of isolates confirmed in April 2023 (n=54). Salmonella Typhimurium ST19 (27.8% in April 2023 vs 14.8% in April 2024) was the most common type confirmed this month. Uncommon serotypes confirmed this month was Salmonella Gaminara (2 human cases since it was first confirmed in New Zealand in 1999) and Salmonella Subsp. (I) ser. 9,12 : m,p : - ST74 (2 human cases since it was first confirmed in New Zealand in 2023). An isolate was typed as Subsp. (I) ser. 9,12 : m,p : - ST74. 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=68) confirmed this month showed a decrease in comparison to the number of isolates confirmed in May 2023 (n=79). Salmonella Enteritidis ST11 and Salmonella Typhimurium ST19 (10.1% and 16.5% in May 2023 vs 14.7% in May 2024) were the most common types confirmed this month. Uncommon serotype confirmed this month was Salmonella Hull (3 human cases since it was first confirmed in New Zealand in 2000)and Salmonella Muenster (15 human cases since it was first confirmed in New Zealand in 1994).

The number of isolates (n=54) confirmed this month showed a slight increase in comparison to the number of isolates confirmed in June 2023 (n=68). Salmonella Paratyphi B var. Java and Salmonella Typhimurium ST19 (0% and 19.1% in June 2023 vs 11.1% in June 2024) were the most common serotypes confirmed this month. Uncommon serotypes confirmed this month were Salmonella Kedougou (16 human cases since it was first confirmed in New Zealand in 1996) and Salmonella Papuana (36 human cases since it was first confirmed in New Zealand in 1990). Salmonella Fulica was confirmed for the first time in humans in New Zealand this month.

The total number of isolates (n=66) confirmed this month showed a slight decrease in comparison to the number of isolates confirmed in July 2023 (n=40).  Salmonella Enteritidis ST11 (7.5% in July 2023 vs. 15.6% in July 2023) was the most common serotype confirmed this month. Uncommon serotypes confirmed this month were Salmonella Colindale (3 human cases since it was first confirmed in New Zealand in 2007), Salmonella Muenster (16 human cases since it was first confirmed in New Zealand in 1994), Salmonella Poona (46 human cases since it was first confirmed in New Zealand in 1998) and Salmonella Wangata (38 human cases since it was first confirmed in New Zealand in 2004). Salmonella Pontypridd was confirmed for the first time in humans in New Zealand this month.

The number of isolates (n=41) confirmed this month showed a decrease in comparison to the number of isolates confirmed in August 2023 (n=65). Salmonella Enteritidis ST11 (9.2% in August 2023 vs 17.1% in August 2024) was the most common serotype confirmed this month. Uncommon serotype confirmed this month was Salmonella Bredeney (15 human cases since it was first confirmed in New Zealand in 1991). 

The number of isolates (n=49) confirmed this month showed a decrease in comparison to the number of isolates confirmed in September 2023 (n=58). Salmonella Typhimurium ST19 (17.2% in September 2023 vs. 12.2% in September 2024) was the most common serotype confirmed this month. Salmonella Edinburg was confirmed for the first time in humans in New Zealand this month. 

The number of isolates (n=90) confirmed this month showed an increase in comparison to the number of isolates confirmed in October 2023 (n=66). Salmonella Enteritidis ST11 (7.6% in October 2023 vs. 16.7% in October 2024) was the most common serotype confirmed this month. Uncommon Salmonella serotypes confirmed this month were S. Hessarek (5 human isolates since it was first confirmed in New Zealand in 1991) and S. Uganda (26 human isolates since it was first confirmed in New Zealand in 1994).

The number of isolates (n=94) confirmed this month showed an increase in comparison to the number of isolates confirmed in November 2023 (n=66). Salmonella Typhimurium ST19 (19.7% in November 2023 vs. 16% in November 2023) was the most common serotype confirmed this month. Uncommon Salmonella serotypes confirmed this month were S. Agbeni (2 human isolates since it was first confirmed in New Zealand in 2017), S. Haifa (30 human isolates since it was first confirmed in New Zealand in 1988), S. Indiana (15 human isolates since it was first confirmed in New Zealand in 1990) and S. Richmond (16 human isolates since it was first confirmed in New Zealand in 1989).

The number of isolates (n=62) confirmed this month showed an increase in comparison to the number of isolates confirmed in December 2023 (n=42). Salmonella Typhimurium ST19 (14.3% in December 2023 vs 24.2% in December 2024) was the most common serotypes confirmed this month. Uncommon Salmonella serotypes confirmed this month were S. Apeyeme (8 human isolates since it was first confirmed in New Zealand in 2011), S. Choleraesuis var. Kunzendorf (10 human isolates since it was first confirmed in New Zealand in 1989) and S. Kottbus (35 human isolates since it was first confirmed in New Zealand in 1989).