Foodborne salmonellosis constitutes a major health problem in many countries. Moreover, the costs associated with salmonellosis could be considerable. There are thus strong arguments for preventive efforts. Ambitious, often government-sponsored, programmes aimed at preventing and controlling salmonellosis in for instance, poultry production represent one alternative to lower salmonellosis-related illness and economic costs. On the other hand, such comprehensive programmes are rather resource-demanding. From the economic point of view the key problem is to find the optimal level for prophylactic measures. The purpose of this study is to compare two different approaches to preventing poultry-borne salmonellosis among humans. We identify and compare the economic costs of illness due to poultry-borne salmonellosis and the costs of salmonella control in England and Wales and Sweden, respectively. An alternative option is then introduced: the concept of competitive exclusion (CE). Our results show that the cost of illness constitutes the major part of the total cost in England and Wales, whereas in Sweden, the control cost amounts to 95% of the total cost. By using the CE concept, the cost of illness due to poultry-borne salmonellosis in England and Wales could be reduced by at least GB pound 12.6 million. These advantages apply to individuals, producers, and to society, and we thus conclude that the CE concept is a very cost-effective way of using scarce resources.