Campylobacter remains the leading cause of foodborne illness in New Zealand, making it a major focus of ongoing food safety research and industry action. Understanding how the pathogen spreads through the poultry food chain, and how it can be controlled, is central to reducing illness and improving public health outcomes.
PHF Science food microbiologist Jo Kingsbury has played a leading role in a series of farm to fork research projects focused on improving Campylobacter control and monitoring, spanning on-farm transmission through to processing, detection, and national surveillance.
Together, this work supports New Zealand Food Safety’s (Ministry for Primary Industries) efforts under the Campylobacter Action Plan, which aims to reduce the burden of campylobacteriosis by 15 per cent between 2025 and 2030.
A persistent public health challenge
In 2024 alone, there were 5,801 notified cases of campylobacteriosis in New Zealand, including 1,038 hospitalisations. However, the true number of infections is likely much higher, as many cases are not diagnosed or reported.
The impact can also extend beyond acute illness. Campylobacter infection is a known trigger for Guillain–Barré syndrome (GBS), a serious neurological condition. In 2024, there were 103 hospitalised cases of GBS in New Zealand, with around one-third estimated to be linked to a previous Campylobacter jejuni infection.
Poultry is the dominant source of infection, with an estimated 84 per cent of New Zealand cases attributed to poultry products. This estimate is based on a Source Assigned Campylobacteriosis in New Zealand study (SACNZ), conducted in 2019 and published in 2021, and the expert colloquium
A farm-to-fork approach to control
Because Campylobacter spreads quickly through poultry flocks, effective control depends on interventions across the entire production chain, not just at processing. Together with collaborators, Jo Kingsbury’s research spans this full pathway, from how the bacteria enters flocks on farm through to processing, detection, and national surveillance.
On farm, the work has examined how Campylobacter is introduced into flocks, including potential transmission routes such as equipment used by chicken catchers and carry-over between flocks via previous shed occupants. It has also assessed the effectiveness of cleaning and disinfection between production cycles. Together, these studies show how rapidly Campylobacter can establish once introduced, and how multiple on-farm pathways contribute to flock colonisation.
At the processing level, research has measured Campylobacter levels across different stages and plants. Findings show that primary processing achieves reductions by about a million-fold (a 6-log reduction), with clear improvements since 2013. However, differences between plants highlight opportunities for further gains. Secondary processing products tend to carry higher levels overall, with drumsticks showing the lowest contamination among portion types, and skin removal alone having limited effect.
As control measures have improved, routine testing has reached a new challenge: Campylobacter levels in regulatory samples are now often close to the limits of detection, making further improvements harder to measure. To address this, PHF Science and collaborators developed a more sensitive testing method that concentrates bacteria using a simple centrifugation step. It detects Campylobacter at seven times lower levels than the current regulatory method and performs better than standard commercial approaches, with evaluation ongoing for potential regulatory use.
Alongside this, PHF Science produces the Annual report concerning Foodborne Diseases in New Zealand for New Zealand Food Safety, providing national surveillance of Campylobacter and other pathogens. These data track trends, measure progress against targets, and help guide policy and future research priorities.
Driving coordinated action across the food chain
This body of work reflects a cross-disciplinary approach involving PHF Science, Massey University, industry partners, and New Zealand Food Safety.
By combining on-farm studies, processing research, diagnostic innovation and national surveillance, the aim is to build a clearer picture of how Campylobacter moves through the poultry system, and where interventions can have the greatest impact. The overall goal is simple but significant: to reduce foodborne illness and strengthen confidence in New Zealand’s food safety system from farm to fork.