Concepts for risk-based surveillance in the field of veterinary medicine and veterinary public health: Review of current approaches

BACKGROUND: Emerging animal and zoonotic diseases and increasing international trade have resulted in an increased demand for veterinary surveillance systems. However, human and financial resources available to support government veterinary services are becoming more and more limited in many countries world-wide. Intuitively, issues that present higher risks merit higher priority for surveillance resources as investments will yield higher benefit-cost ratios. The rapid rate of acceptance of this core concept of risk-based surveillance has outpaced the development of its theoretical and practical bases. DISCUSSION: The principal objectives of risk-based veterinary surveillance are to identify surveillance needs to protect the health of livestock and consumers, to set priorities, and to allocate resources effectively and efficiently. An important goal is to achieve a higher benefit-cost ratio with existing or reduced resources. We propose to define risk-based surveillance systems as those that apply risk assessment methods in different steps of traditional surveillance design for early detection and management of diseases or hazards. In risk-based designs, public health, economic and trade consequences of diseases play an important role in selection of diseases or hazards. Furthermore, certain strata of the population of interest have a higher probability to be sampled for detection of diseases or hazards. Evaluation of risk-based surveillance systems shall prove that the efficacy of risk-based systems is equal or higher than traditional systems; however, the efficiency (benefit-cost ratio) shall be higher in risk-based surveillance systems. SUMMARY: Risk-based surveillance considerations are useful to support both strategic and operational decision making. This article highlights applications of risk-based surveillance systems in the veterinary field including food safety. Examples are provided for risk-based hazard selection, risk-based selection of sampling strata as well as sample size calculation based on risk considerations

Redesign of Water Distribution Systems for Passive Containment of Contamination

Most water distribution systems in the United States are designed as looped systems in order to allow multiple pathways for delivery of water to customers. However, these designs also have the negative consequence that, if the system is contaminated, then the contamination may travel widely through the system and cause widespread impacts. In this paper, an alternative design concept is suggested based on the creation of distribution blocks that subdivide and isolate the system so as to limit contaminant movement. A model-based case study involving a large distribution system was used to evaluate the effectiveness of the distribution block concept. A comparison of the original looped system and the redesigned system also included the following other performance indicators: water age, reliability, and fire flow performance. The analysis showed that for this system, there was a very significant decrease in the water security vulnerability impacts with minimal effects on the other performance indicators.The U.S. Environmental Protection Agency through its Office of Research and Development partially funded and collaborated in the research described here. The research has been subjected to the Agency’s review and has been approved for publication. Note that approval does not signify that the contents necessarily reflect the views of the Agency. Mention of trade names, products, or services does not convey official EPA approval, endorsement, or recommendation