Molecular-based surveillance of campylobacteriosis in New Zealand contributed to the implementation of interventions that led to a 50 per cent reduction in notified cases and hospital admissions of the country's most important zoonosis. From a pre-intervention high of 384 per 100,000 population in 2006, incidence dropped by 50 per cent in 2008; a reduction that has been sustained since.

In Euro Surveillance, Petra Muellner of the mEpiLab at the Institute of Animal, Biomedical and Veterinary Science at Massey University and co-authors present an article that illustrates many aspects of the successful use of molecular-based surveillance, including the distinction between control-focused and strategy-focused surveillance and advances in source attribution.

They discuss how microbial genetic data can enhance the understanding of epidemiological explanatory and response variables and thereby enrich the epidemiological analysis. Sequence data can be fitted to evolutionary and epidemiological models to gain new insights into pathogen evolution, the nature of associations between strains of pathogens and host species, and aspects of between-host transmission.

With the advent of newer sequencing technologies and the availability of rapid, high-coverage genome sequence data, the group says that such techniques may be extended and refined within the emerging discipline of genomic epidemiology.

In the article, the researchers summarise the experience gained in New Zealand with molecular-based surveillance of campylobacteriosis and to discuss how this experience could be used to further advance the use of molecular tools in surveillance.

In their conclusions, Muellner and co-authors state that the approach taken in New Zealand, which includes the first large scale implementation of effective regulatory Campylobacter control measures in broilers, is of high relevance internationally, including Europe. Findings have been incorporated in scientific opinions of the European Food Safety Authority. In 2008, it was acknowledged that the multilocus sequence typing (MLST) approach to source attribution developed in New Zealand may be the way forward and the approach is being used in several European countries, including the Netherlands and Scotland. The New Zealand experience was also included in an assessment of the extent to which meat derived from broilers contributes to human campylobacteriosis at the European Union level.

In New Zealand, the researchers stressed, it has been learned that close collaboration between laboratories and epidemiologists is extremely important for the success of molecular-based surveillance: in that country, this started when the sentinel surveillance site was first set up. In a small and geographically isolated country, such early collaboration is likely to be more easily achieved; nevertheless, the general principle still applies and could add value to molecular surveillance in other countries, according to Muellner and co-authors.

Reference

Muellner P., Pleydell E., Pirie R., Baker M.G., Campbell D., Carter P.E. and French N.P. 2013. Molecular-based surveillance of campylobacteriosis in New Zealand – from source attribution to genomic epidemiology. Euro Surveill. 2013;18(3):pii=20365.

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