Biological hazard research

Faecal source tracking, water management, Norovirus, shellfish

Shellfish may become contaminated by potential human pathogens when they come into contact with water containing human sewage or agricultural runoff. MPI contracted ESR to identify and evaluate available chemical and microbial source tracking methods and technologies that could be used as indicators of human or animal faecal contamination, particularly in NZ shellfish growing areas, thereby offering opportunity to better manage these areas minimising commercial and public health impacts.

This SIS is prepared by New Zealand Food Safety (NZFS) risk assessors to provide context to the following report for NZFS risk managers and external readers.

NZFS commissioned a project to inform risk models by providing estimates on expected bacterial growth for different scenarios of

chiller failure. This was to facilitate faster decisions around acceptance/rejection criteria for raw milk, and so limit the quantity of

milk discarded. The outcome of this work is guidance on the potential micro-organism growth during chiller failure, enabling a

robust estimate on if milk is not fit for purpose.

Extended shelf-life milk, when produced by thermal processing, applies parameters between those used for traditional pasteurisation and ultra-high-temperature sterilisation. The goal of this study was to identify the food safety issues that must be considered. Of particular concern is the presence of spore-forming organisms. This review supports the current approach of considering production on a case-by-case basis, and requiring validation studies to assess the bactericidal effect of a process.

Clostridium botulinum and other Clostridium species produce potent neurotoxins (BoNT) that cause botulism. These anaerobic organisms reside naturally in soils and marine sediments and can contaminate seafood. Given suitable storage conditions, they can grow and produce the toxin in the seafood, making consumers ill and even causing death.

The quantity and pattern of antimicrobial use in animals affects the occurrence of antimicrobial resistance in bacteria from animals and in animal-derived food, and hence it affects human exposure to these resistant bacteria. When pathogens are resistant to essential human antimicrobials, the human health consequences include increased treatment failures, increased severity of infections, and infections that would otherwise not have occurred.

The purpose of a Risk Profile is to provide contextual and background information relevant to a food/hazard combination so that risk managers can make decisions and, if necessary, take further action. Risk Profiles include elements of a qualitative risk assessment, as well as providing information relevant to risk management. Risk profiling may result in a range of activities e.g. immediate risk management action, a decision to conduct a quantitative risk assessment, or a programme to gather more data, ranking of a particular food safety issue.

The purpose of a Risk Profile is to provide contextual and background information relevant to a food/hazard combination so that risk managers can make decisions and, if necessary, take further action. Risk Profiles include elements of a qualitative risk assessment, as well as providing information relevant to risk management. Risk profiling may result in a range of activities e.g. immediate risk management action, a decision to conduct a quantitative risk assessment, or a programme to gather more data, ranking of a particular food safety issue.

The food/hazard combination addressed by this risk profile is Salmonella (non-typhoidal) in pork and pork products.

There are two pathogenic species of the Cryptosporidium parasite that infect humans; C.
parvum and C. hominis. C. parvum can also infect bovines. When excreted by the host, the
environmental form of Cryptosporidium is the oocyst, which contains four sporozoites, and is
a very resilient organism that can withstand many environmental stresses including
chlorination.

The Clostridium botulinum types involved in infant botulism belong to Group I and produce
type A, B and to a lesser extent type F toxins. When spores of the organism are ingested by
infants (who have an incomplete intestinal microflora) they may become established and
grow.

Ciguatera fish poisoning is solely caused by the consumption of seafood contaminated with
toxins produced by dinoflagellate microalgae, particularly Gambierdiscus toxicus. While
there are isolated reports of ciguatera fish poisoning resulting from consumption of nonfinfish
species, the disease is usually caused by the consumption of large finfish species from
circumtropical regions.

This Risk Profile concerns B. cereus in rice, as this food has often been associated with food
poisoning outbreaks where B. cereus has been identified as the causative agent. B. cereus
bacteria may produce either or both of diarrhoeal and emetic toxins. The disease caused is
generally considered to be mild and of short duration.

This paper is part of the New Zealand Food Safety Authority’s scientific evaluation of foodborne hazards. The focus is the bacterium Mycobacterium avium subspecies paratuberculosis (MAP), which has been reported as a possible food contaminant, particularly in dairy products.