The Challenge of Estimating the Burden of an Underreported Disease

Abstract

This chapter focuses on the epidemiologic and surveillance challenges posed by food-borne viral disease. The exemplar used is norovirus (NoV), although most of the principles apply equally to other viruses transmitted through food. In a study examining archived DNA and cDNA from stool samples from a large population-based case-control study of infectious intestinal disease (IID) in England, the increased detection of NoV was statistically significant in all age groups. This study illustrated dramatically that what you find in stool samples depends not only on what you look for but also how hard you look for it. There are at least three ways in which the public health system can militate against a good understanding of the burden of food-borne viral gastroenteritis. For example, in a survey of environmental health departments (sanitarians) in England, 64% of respondents always investigated a case of viral gastroenteritis reported to them (compared with 96% for Salmonella enteritis). For an infection that is, perhaps, classically regarded as predominantly outbreak related, the approach to the investigation of outbreaks is also variable. It is essential that the understanding of the contribution of NoV and other viruses to the burden of acute gastroenteritis (AGE) should be improved by using DNA microarray technology in diagnostic laboratories, perhaps as part of national sentinel networks. Integrating virological investigations with standardized epidemiologic data should enhance the detection of NoV and hence the understanding of the role of NoV in food-borne disease.