ABSTRACT

In the decade since the preparation of the chapter on bacterial and mycotic diseases for the first edition of this book, innumerable advances have improved our ability to diagnose, treat, and prevent many infectious diseases. Unfortunately, despite this significant progress, new challenges have arisen to test the ability of practitioners to deal with serious bacterial infections. Bacterial disease secondary to primary conditions, such as those caused by morbilliviruses and phytotoxins, are now well recognized as major causes of mortality in wild marine mammal populations. In addition, other bacterial pathogens are infecting new or previously unrecognized hosts (Hernandez et al., 1998; Harvell et al., 1999). Diseases (such as those caused by mycobacterial species), which were seldom referenced in the earlier marine mammal literature, have emerged as significant causes of morbidity and mortality in both wild and captive populations of marine mammals (see Chapter 2, Emerging Diseases). Brucellosis, long thought to be a disease confined to terrestrial mammals, has been documented in marine mammals in several areas of the world. Increasingly, there are reports of altered immune response and a decrease in natural resistance to bacterial and viral infection in marine mammals exposed to high levels of anthropogenic substances such as organohalogens (Thompson and Hall, 1993; De Guise et al., 1995a; Parsons and Jefferson, 2000). Dissenting positions regarding this relationship also exist, and it is unfortunate that, although details of tissue contaminant levels in marine mammals abound, the ultimate consequences of these elevated levels remain speculative (Wilson et al., 1999; see Chapter 22, Toxicology).