No abstract

An assessment of the risk of illness associated with Escherichia coli O157:H7 in ground beef was drafted in 2001. The exposure assessment considers farm, slaughter, and preparation factors that influence the likelihood of humans consuming ground beef servings containing E. coli O157:H7 and the number of cells in a contaminated serving. Apparent seasonal differences in prevalence of cattle infected with E. coli O157:H7 corresponded to seasonal differences in human exposure. The model predicts that on average 0.018% of servings consumed during June through September and 0.007% of servings consumed during the remainder of the year are contaminated with one or more E. coli O157:H7 cells. This exposure risk is combined with the probability of illness given exposure (i.e., dose response) to estimate a U.S. population risk of illness of nearly one illness in each 1 million (9.6 x 10(-7)) servings of ground beef consumed. Uncertainty about this risk ranges from about 0.33 illness in every 1 million ground beef servings at the 5th percentile to about two illnesses in every 1 million ground beef servings at the 95th percentile.

Fragmentary data indicate that zoonotic parasites cause human illnesses with medical costs and productivity and disability losses totalling billions of dollars annually. Food is an important vehicle for some of these parasitic diseases. The cost to public health is not reflected in the priorities given to these parasitic diseases in either research or public health planning. In this article, Tanya Roberts, Darwin Murrell and Suzanne Marks discuss the cost of toxoplasmosis, taeniasis, cysticercosis, trichinellosis and other foodborne parasitic diseases.Worldwide economic losses caused by foodborne parasitic zoonoses are difficult to assess. The prevalence of specific parasites in the food supply varies between countries and regions, and data on prevalence are fragmentary. Dietary preferences and food preparation practices affect the probability of eating contaminated food. For example, consuming raw or undercooked meat, poultry or seafood increases risk. There are few studies estimating the costs of parasitic foodborne disease. Generally, these studies estimate medical costs and productivity losses due to worker illness or death, but may include different cost categories or use different methodologies and assumptions. This review summarizes the available human illness cost estimates of the following foodborne parasitic zoonoses: toxoplasmosis, taeniasis/cysticercosis, trichinellosis and opisthorchiasis. The cost estimates are fragmentary and are primarily for developed countries because of the lack of suitable economic data from other countries.

Microbial risk assessment is emerging as a new discipline in risk assessment. A systematic approach to microbial risk assessment is presented that employs data analysis for developing parsimonious models and accounts formally for the variability and uncertainty of model inputs using analysis of variance and Monte Carlo simulation. The purpose of the paper is to raise and examine issues in conducting microbial risk assessments. The enteric pathogen Escherichia coli O157:H7 was selected as an example for this study due to its significance to public health. The framework for our work is consistent with the risk assessment components described by the National Research Council in 1983 (hazard identification; exposure assessment; dose-response assessment; and risk characterization). Exposure assessment focuses on hamburgers, cooked a range of temperatures from rare to well done, the latter typical for fast food restaurants. Features of the model include predictive microbiology components that account for random stochastic growth and death of organisms in hamburger. For dose-response modeling, Shigella data from human feeding studies were used as a surrogate for E. coli O157:H7. Risks were calculated using a threshold model and an alternative nonthreshold model. The 95% probability intervals for risk of illness for product cooked to a given internal temperature spanned five orders of magnitude for these models. The existence of even a small threshold has a dramatic impact on the estimated risk.

Guillain-Barré syndrome (GBS) is an autoimmune disease characterized by acute neuromuscular paralysis. Of an estimated annual number of 2628-9575 US cases, 526-3830 are triggered by Campylobacter infection. Research objectives were to identify the lifetime consequences of GBS and, when possible, to quantify their economic burden. The cost-of-illness method was used to calculate annual societal resources spent on medical care and lost productivity due to illness or premature death from Campylobacter-associated GBS. Estimated total costs (in US$) of Campylobacter-associated GBS ($0.2-$1.8 billion) were added to previously estimated costs of campylobacteriosis ($1.3-$6.2 billion) for a total annual cost from Campylobacter of $1.5-$8.0 billion (1995 dollars). It is concluded that up to $8.0 billion in US human illness costs are spent annually because of Campylobacter infection. Economic evaluation of the other costs associated with GBS, such as physical and psychological costs, would increase these estimates.