Food Focus November 2008

The cost of foodborne disease in New Zealand

NZFSA’s Science Group has an ongoing series of projects to develop a risk-ranking system for microbiological hazards in the food supply. Assessing the foodborne risk for consumers is obviously the primary concern and cost is factored in, particularly if people can’t work because of illness. This latest study estimates what that cost might be

NZFSA’s risk-ranking system is used to set strategies and work priorities proportional to the foodborne risks faced by consumers. For example, each year NZFSA reviews its Campylobacter strategy to see if new actions need to be set in response to the results achieved and new information gathered over the past year. Other work streams are similarly reviewed in response to new information.

To further the development of its risk-ranking system, NZFSA contracted ESR to estimate the number of work days lost to gastrointestinal illness (reported in Food Focus in February 2008). This latest study involved preparing estimates for the direct and indirect economic burden of certain gastrointestinal diseases in New Zealand.

The study found that the total cost to New Zealand society from foodborne Campylobacter, Salmonella, Listeria, E. coli, Yersinia and norovirus infections is estimated to be $86 million. About 90% of this cost can be attributed to lost productivity caused by workforce absence. Of particular relevance to NZFSA’s Campylobacter strategy is that campylobacteriosis accounted for approximately 90% of the total estimated cost.

In New Zealand campylobacteriosis is the most frequently reported gastrointestinal illness. Although our overall rate of acute gastrointestinal illness is comparable to other developed countries (at 7.8%), our rate of campylobacteriosis is higher.

Estimates were made of the costs resulting from each incident case of foodborne microbial disease. As with a previous New Zealand study, the highest cost per case was associated with listeriosis, while norovirus infection had the lowest cost per case.

The estimates from the current project are only approximate because of:

• uncertainty about the annual number of cases of the diseases studied and the proportion of these diseases that are foodborne (see Figure 1)

• lack of New Zealand-specific information about the epidemiology and clinical course of the diseases included in the study

• lack of information on the extent of caregiver absence from work.

The total cost of illness was considered in terms of direct costs, indirect costs and intangible costs:

• direct health-care costs – this includes costs for GP consultations and medications (either over the counter or prescription), it doesn’t separate out the proportion paid by some people themselves or subsidies

• direct non-health-care costs – travel costs to and from a GP consultation or a hospital

• indirect non-health-care costs – costs to society due to lost production resulting from illness (for employees in paid work).

The approach adopted makes some international comparisons possible for ‘cost of illness’ studies for foodborne illness. For instance, a similar Dutch study provides cost estimates for Campylobacter, Salmonella and norovirus-related diseases for the Netherlands. When figures are corrected for differences in population and exchange rates, the Dutch estimate for the cost of illness associated with Campylobacter is approximately one-sixth of the estimate for New Zealand, Salmonella is approximately 1.5 times the estimate for New Zealand and norovirus is four times the estimate for New Zealand. These comparisons will be influenced by the differences in the incidence of these disease between the two countries as well as differences in the cost of healthcare.

This study is one component in a long-term project NZFSA is working on to develop a risk ranking system that can be applied to both chemical and microbiological hazards.

NZFSA science research reports are available here

Figure 1: The reporting pyramid for foodborne illnesses

Estimated mean incidence for reported cases in New Zealand by pathogen, 2005