Yersinia Isolates 2019

Yersinia data has been confounded in a number of ways for 2019:

• Laboratories servicing 50% of NZ are no longer testing for Yersinia pseudotuberculosis, as the target is not in the multiplex PCR kit they have chosen to use.  Therefore, when we noted an increase in this species during September 2019, this increase was difficult to quantitate and investigate. Genomic analysis of available isolates indicated cases did not all conform to a single cluster type and were therefore unlikely to be from a common source.

• A laboratory testing 1/6 of the NZ’s samples ceased referral of Yersinia isolates in November 2018 and has not resumed this referral.

The ongoing increase in Yersinia cases in NZ, is real and sustained and is due to the emergence of biotype2/3 serotype O:9.

The Enteric Reference laboratory introduced serotyping of Yersinia enterocolitica biotype 1A in September 2019. ESR is only screening with a small number of antisera and organisms not conforming to a specific serotype are being reported as being not O3; O5; O8; O9. This designation will comprise a heterogeneous group and is not in itself a type.