Pullorum disease and fowl typhoid--new thoughts on old diseases: a review.

Fowl typhoid and pullorum disease are two distinct septicaemic diseases largely specific to avian species and caused by Salmonella Gallinarum and Salmonella Pullorum, respectively. They were first described more than one century ago. Since their discovery, many efforts have been made to control and prevent their occurrence in commercial farming of birds. However, they remain a serious economic problem to livestock in countries where measures of control are not efficient or in those where the climatic conditions favour the environmental spread of these microorganisms. During the past 15 to 20 years there has been an explosion of genetic and immunological information on the biology of these two organisms, which is beginning to contribute to a better understanding of the organisms and their interaction with the host. However, it is not enough simply to understand the pathology in greater and greater detail. What is needed, in addition to this increase in basic knowledge, is creative thinking to challenge existing paradigms and to develop really novel approaches to infection control.