Human salmonella isolates 2009

Annual summary 2009

There were 1176 human Salmonella isolates confirmed in 2009 (2008 n= 1399). S. Typhimurium phage type 160 remained the predominant strain, representing 9% of total isolates (9.7% 2008). S. Typhimurium phage type 9 was isolated from a 2 month old baby who had died of sudden infant death syndrome in the Otago region. Since 2005 the numbers of S. Typhimurium phage type 9 have progressively increased from 7 cases in 2005, 12 in 2006, 14 in 2007, 17 in 2008, to 24 in 2009. This phage type is found predominately in cattle.

There were four significant outbreaks:
S. Typhimurium RDNC-Aug 08 - The outbreak started in December 2008 with a total of 48 cases. No food source was linked to this outbreak.

S. Typhimurium phage type 1 - 38 cases. No food source was linked to the outbreak. The results of the case control study however suggested that the cases from Gisborne were linked to the consumption of watermelon from a grower in the Gisborne region. Molecular typing of the 38 cases revealed that the 19 cases from the Auckland region were not linked to the outbreak in Gisborne.

S. Typhimurium phage type 42 - 75 cases. The outbreak started in October 2008. The majority of these cases were connected to the consumption of raw flour. The same phage type was also isolated from bags of unopened flour and resulted in a voluntary withdrawal of the product by the manufacturer.

S. Typhimurium phage type 12a variant 09 – 11 cases. No food source was linked to this outbreak but all cases had recent overseas travel via Australia (or contact with someone with overseas travel) during the incubation period. This phage type is common in Australia but known as phage type 108 or 170 depending on the state. The Enteric Reference Laboratory will type Australian isolates for comparison with the New Zealand isolates. Results of molecular and phenotypic analysis will be posted on the website as they become available.