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Risk Profiles

The following microbiological Risk Profiles have been prepared for the New Zealand Food Safety Authority by the Institute of Environmental Science and Research Limited (ESR).

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. The information will also prove useful to regulators when developing requirements for risk-based food control programmes, and for approved auditors when assessing the safety of food processes. More about risk profiles.

Food industry associations, food businesses and food safety consultants can also use this information to help understand the microorganisms they need to control in their, or their client's, food processes and their associated public health significance. 

Bacillus spp. in rice
Illness caused by Bacillus cereus is not a notifiable disease in New Zealand. Therefore the only data concerning illness will derive from outbreaks or investigations of specific incidents. B.cereus is responsible for 1.2 - 4.5% of outbreaks reported in New Zealand. The limited data from reported outbreaks indicate that rice or rice dishes are reasonably common vehicles for the small proportion of outbreaks attributed to B. cereus or other Bacillus species. Takeaways, often Chinese-style or Indian-style, are premises frequently cited as a source of the implicated food. This suggests that, as in other countries, a small proportion of rice is not handled in a safe manner, allowing the regeneration and growth of spores.

Campylobacter jejuni/coli in poultry
Campylobacter is the most frequently notified cause of enteric disease in New Zealand. Infection by the organism results primarily in diarrhoea, although in some cases more serious clinical consequences may result. While a New Zealand case-control study linked consumption of chicken with Campylobacter infection and several outbreaks of campylobacteriosis identified undercooked chicken as the transmission vehicle, contact with animals or contaminated waterways are also considered to be significant routes of transmission.

Campylobacter jejuni/coli in Mammalian and Poultry Offals
The consumption of poultry and mammalian offal is low in comparison to other meat types. However the high prevalence of Campylobacter in raw sheep and chicken livers is of concern, especially when some advice to consumers is to cook chicken livers "until they're pink in the middle" or "lightly sautéed". In addition, there may be a risk of infection through exposure due to the handling of offal for pet food and/or cross contamination from the exterior of packs of offal which have been shown to frequently contaminated.

Camplobacter jejuni/coli in red meat
Seventeen outbreaks of campylobacteriosis in New Zealand from January 1999 to August 2004 have been associated, albeit weakly, with red meat consumption. Only barbecued lamb, probably minced meat, has been identified as a risk factor in case-control studies of campylobacteriosis conducted in New Zealand. Nevertheless there are good data indicating low but consistent prevalence of contamination across pork, beef, and sheep meat, and red meat is a frequently consumed food. On this basis it seems reasonable to assign red meat consumption as an identified but minor risk factor for exposure to Campylobacter in New Zealand.

Ciguatoxins in Seafood
Ciguatera fish poisoning (CFP) usually occurs when finfish contaminated with ciguatoxins (algal biotoxins) are consumed. CFP is not a notifiable disease in New Zealand, hence under-reported, although several cases per year come to the attention of the public health system. Contaminated fish generally originate from the Pacific Islands, not New Zealand waters. Hence, the risk of CFP to the general New Zealand population appears to be low and more likely to be travel-acquired. However, the risk for the Pacific Island population is considered higher because of private importation of potentially ciguatoxic fish for personal consumption

 Clostridium botulinum in honey
Clostridium botulinum intoxication results in serious clinical consequences, with 80% of cases requiring hospitalisation. Fortunately disease caused by this organism is very rare in New Zealand, the last known case being in 1984. There are a number of important types in food:
Group I - Types A, B, and F (proteolytic strains)
Group II - Types B, E and F (non proteolytic strains).
There are two manifestations of disease relevant to food; foodborne botulism and infant botulism. Cases are associated usually with inadequate canning or bottling because the organism can grow and produce toxin under anaerobic conditions. Historically, a number of overseas outbreaks occurred when home canning was common. Honey is the only laboratory confirmed dietary source of the organism in infant cases. There have been no reported cases of infant botulism in New Zealand.

This is an interim report, as NZFSA sponsored work continues into the prevalence and types of C. botulinum in the New Zealand environment.

Clostridium botulinum in ready-to-eat smoked seafood in sealed packaging
Clostridium botulinum intoxication results in serious clinical consequences, with 80% of cases requiring hospitalisation. Fortunately disease caused by this organism is very rare in New Zealand, the last known case being in 1984. There are a number of important types in food:
Group I - Types A, B, and F (proteolytic strains)
Group II - Types B, E and F (non proteolytic strains). Type E is most commonly associated with marine environments
There are two manifestations of disease relevant to food; foodborne botulism and infant botulism. Cases are associated usually with inadequate canning or bottling because the organism can grow and produce toxin under anaerobic conditions. Historically, a number of overseas outbreaks occurred when home canning was common. The type E foodborne outbreaks associated with fish have predominantly involved traditional native dishes.

This is an interim report, as NZFSA sponsored work continues into the prevalence and types of C. botulinum in the New Zealand environment.

Cryptosporidium spp. in Shellfish
Evidence from New Zealand surveys of freshwater, sewage effluents, livestock and human faecal samples indicates that the parasite Cryptosporidium is widespread in the New Zealand environment and therefore a likely contaminant of shellfish. Nevertheless, only seven of approximately 8000 notified cases of cryptosporidiosis in New Zealand since 1996 have been reported as being associated with consumption of shellfish and in none was shellfish confirmed as the source of the infection. While New Zealand does not have any data on the prevalence of Cryptosporidium oocysts in shellfish, a 2007 United States quantitative risk assessment concluded that the numbers of oocysts in shellfish may often be too low to cause cryptosporidiosis in healthy individuals, despite the ineffectiveness of depuration, survival of the oocyst in seawater and many shellfish being consumed raw or lightly cooked. Overall, the risk of Cryptosporidium infection from consuming shellfish in New Zealand appears to be very low. 

Listeria monocytogenes in ice cream
The rate of reported invasive listeriosis in New Zealand is similar to that found in like countries, and a proportion of these cases are likely to be food-borne. This Risk Profile concerns Listeria monocytogenes in ice cream, and no evidence has emerged to link consumption of this commodity with cases of L. monocytogenes infection in New Zealand.

Listeria monotogenes in Low Moisture Cheese
Domestically-produced and imported low moisture cheeses (moisture content of less than 50%) sold in New Zealand are manufactured using pasteurized milk or milk that has been treated by an equivalent antimicrobial treatment (e.g. thermisation and aging). Therefore, contamination with Listeria monocytogenes is unlikely unless introduced post-pasteurisation from environmental sources, added ingredients or further processing such as grating. Surveys of low moisture cheese suggest that contamination with L. monocytogenes is infrequent and that growth in product is unlikely. Even taking into account the high consumption of low moisture cheese, the available data indicates that L. monocytogenes in low moisture cheese does not represent a significant risk to human health.

Listeria monocytogenes in processed ready-to-eat meats
Listeria monocytogenes infections are rare in New Zealand at less than 20 per year, although are usually serious with a case fatality rate of around 20%. Listeria are ubiquitous in the environment and while most people ingest small numbers daily without subsequent illness, at-risk groups of the population may become ill. Foods with long shelf lives that are stored under refrigeration are usually associated with Listeria because, unlike other pathogens, they can grow at refrigeration temperatures. Several notified cases in New Zealand and an outbreak of non-invasive listeriosis in February/March 2000 associated with corned silverside and ham indicate that processed ready-to-eat meats are a route of infection for listeriosis in New Zealand.

Listeria monocytogenes in ready-to-eat salads
Listeria monocytogenes infections are rare in New Zealand at less than 20 per year, although are usually serious. Listeria are ubiquitous in the environment and while most people ingest small numbers daily without subsequent illness, at-risk groups of the population may become ill. Foods with long shelf lives that are stored under refrigeration are usually associated with Listeria because, unlike other pathogens, they can grow at refrigeration temperatures. Nevertheless, there is little indication that L. monocytogenes infection in New Zealand is associated with ready-to-eat salads without dressings (lettuce and cabbage based salads, and excludes coleslaws or salads with non-vegetable ingredients). Data on the prevalence of L. monocytogenes in New Zealand ready-to-eat salads are limited. Nevertheless, application of Good Agricultural Practice (GAP) during growth of the vegetables, and risk management measures including Food Safety Programmes and testing for L. monocytogenes by processors ensure that the risk in New Zealand is minimised.

Listeria monocytogenes in Soft Cheeses
Soft cheeses are defined as having a moisture content of >50%. Both domestically produced and imported cheeses are considered. All soft cheese manufactured in or imported into New Zealand will be made from pasteurised milk. Data on the prevalence of L. monocytogenes indicate that contamination rates are very low. Due to the ubiquitous nature of the organism, contamination with L. monocytogenes, if it does occur, is more likely to take place post-pasteurisation. Consumption of soft cheese in New Zealand is modest, and considered against the mandatory pasteurisation requirements and very low prevalence of contamination, the current risk to the general New Zealand population is considered low, although susceptible populations will have a greater risk. Because L. monocytogenes is a psychrotroph, refrigeration can not be relied upon to inhibit growth if contamination does occur.

Mycobacterium bovis in milk (Amended November 2003)
Although Mycobacterium bovis is the cause of a small proportion of the tuberculosis cases in New Zealand, public health significance is minimal. Cows milk is the food most commonly associated with transmission to humans. However, pasteurization and control of infected ruminant animals have been effective in controlling the organism. Many cases in New Zealand are due to the re-emergence of infection in older people who were infected prior to routine pasteurisation. Demonstration of the safety of New Zealand produced food with respect to this pathogen is important for international trade.

Mycobacterium bovis in Red Meat
Tuberculosis is most commonly caused by Mycobacterium tuberculosis, but a proportion of human cases are caused by Mycobacterium bovis. The proportion of total tuberculosis cases caused by M. bovis in New Zealand is similar to other developed countries. The significance of M. bovis as a cause of tuberculosis has decreased since the widespread introduction of milk pasteurisation. While transmission of tuberculosis to humans through consumption of M. bovis infected meat is possible no cases of this have been confirmed in New Zealand or overseas.

Natural Toxins in New Zealand Crop Plants
Crop plants contain many hundreds of chemicals, some of which have beneficial nutritional consequences for humans if consumed, while others may result in adverse health consequences for humans. Some plant chemicals may be both beneficial and harmful, depending on the dose consumed and the context of the consumption event. Chemicals naturally present in plants or produced by the plant in response to environmental factors that can elicit adverse health effects in humans or animals are often referred to as natural plant toxins. This report is a qualitative assessment of the risks associated with natural toxins in crop plants available in New Zealand, based on currently available data.

Norwalk-Like virus in mollusca (raw)
Noroviruses, previously known as Norwalk-like virus (NLV), are the cause of many cases of gastrointestinal disease in New Zealand. Person-to-person spread is common. Food can be contaminated through poor hygiene practices by infected food handlers or, because the food has been grown in a contaminated environment. Of the outbreaks of NLV infection in New Zealand that have been associated with food, the most common food type has been raw seafood (including both domestic and imported shellfish).

Salmonella (non-typhoid) in and on eggs
 Non-typhoid Salmonellae cause salmonellosis; the second most frequently notified enteric disease in New Zealand. A diverse range of foods may carry the organism. New Zealand is fortunate in having a poultry industry and egg supply in which types of Salmonella that have caused major problems overseas (S. Enteritidis PT4 and S. Typhimurium DT104) are not endemic.  Although eggs and egg dishes have been regularly implicated in reported outbreaks of salmonellosis in New Zealand, this has rarely been supported by laboratory evidence.

Salmonella (non-typhoid) in poultry (whole and pieces) (October 2002)            Updated document (June 2004)
Non-typhoid Salmonellae cause salmonellosis; the second most frequently notified enteric disease in New Zealand. A diverse range of foods may carry the organism. The organism survives drying well, and is less sensitive to heat treatment when present in dry foods. While foods such as poultry and pig meat are regarded as important sources of infection, contact with animals is a major route of infection.

Shiga toxin-producing Escherichia coli (STEC) in leafy green vegetables
Shiga-toxin producing Escherichia coli (STEC) infection, in particular that of E. coli O157:H7, may result in serious illness in children. A recent nationwide outbreak in the USA was caused by contaminated spinach. Fortunately, there is little indication of foodborne transmission in New Zealand, and none implicating leafy vegetables. Two surveys totaling ~600 samples of mostly lettuce and spinach have failed to detect E. coli O157:H7. Horticultural practices only allowing the use of fully composited faecal waste minimizes the risk of STEC infection from leafy vegetables.

Shiga toxin-producing Escherichia coli (STEC) in raw milk
Shiga toxin-producing Escherichia coli (STEC) are a diverse group of E. coli serotypes, the most well-known being E. coli O157:H7. While the sale of raw milk in New Zealand is prohibited, rural populations and visitors, may frequently consume it. Approximately 10% of notified human cases of STEC infection in New Zealand, mostly E. coli O157:H7, report consumption of raw milk although are also exposed to other risk factors in the farm environment. E. coli O157 has been reported, albeit rarely, in faecal samples from dairy and beef cattle, and a single infant case has been associated with contact with raw milk. However, there is insufficient data on the prevalence and numbers of STEC in raw milk to robustly estimate the risk from consumption of raw milk in New Zealand. Currently, milk for sale in New Zealand must be pasteurised.

Shiga Toxin-Producing Escherichia coli in red meat and meat products
Shiga-like toxin producing Escherichia coli (STEC) are a diverse group of E. coli serotypes, the most well known of which is E. coli O157:H7. The clinical consequences of infection may be serious, including kidney failure and death in children. First recognized in the United States in 1982, the first human case in New Zealand occurred in 1993. While overseas studies have consistently linked human cases of STEC infection and particularly E. coli O157:H7 to consumption of red meat in the form of undercooked hamburgers, not one case in New Zealand has been associated with regulated foods.

Shiga-like toxin producing Escherichia coli in uncooked comminuted fermented meat products (February 2003)         Updated document (August 2007)
Shiga-like toxin producing Escherichia coli (STEC) are a diverse group of E. coli serotypes, the most well known of which is E. coli O157:H7. The clinical consequences of infection may be serious, including kidney failure and death in children. First recognized in the United States in 1982 and consistently linked to undercooked hamburgers, New Zealand cases since first detected in 1993 have not been associated with regulated foods. While uncooked comminuted fermented meat (UCFM) products might appear to be a higher risk, well controlled processing to lower the pH and water activity control STECs, even more acid tolerant variants.

Toxoplasma gondii in red meat and meat products
Toxoplasma gondii is a protozoan parasite that causes disease in humans with a range of outcomes including, at worst, miscarriages. Contact with cats, important in the life cycle of the parasite, and their faeces is an important route of infection. Similarly cysts in the muscle tissue of meat animals may result in infection when eaten. The significance of human infections, especially congenital toxoplasmosis, in New Zealand is unknown and has been identified as a knowledge gap.

Vibrio parahaemolyticus in seafood
Vibrio parahaemolyticus is a bacterium that requires salt for optimum growth. Occurrence is usually restricted to estuarine and coastal marine waters, but a high proportion of isolates from seawater are not pathogenic to humans. Numbers of V. parahaemolyticus are higher in seafoods harvested when the water is warmer. Infection with V. parahaemolyticus is not a notifiable illness in New Zealand and, hence, systematic incidence data on cases of infection are not available. The occurrence of V. parahaemolyticus infection in New Zealand appears to be strongly linked to the personal importation and consumption of seafood by Pacific Islanders, although infection associated with recreationally harvested mussels has been reported.

Yersinia enterocolitica in pork
Pathogenic strains of Yersinia enterocolitica cause yersiniosis. New Zealand has a high incidence of yersiniosis in comparison to countries such as Australia, the United Kingdom and the United States. Effective cooking or pasteurisation will eliminate Y. enterocolitica from foods. However there is still the potential for cross contamination from uncooked foods (especially meats) to other foods that are then not cooked before consumption. Pigs are known to be frequently contaminated with Y. enterocolitica. Pork consumption has consistently been associated with yersiniosis in studies in New Zealand and overseas, but may not be the most important source of infection.