Glanders and melioidosis: A zoonosis and a sapronosis: "Same Same, But Different"

Glanders, caused by infection with Burkholderia mallei, primarily causes infection in equines, but may be transmitted to humans, and thus qualifies as a true zoonosis. Melioidosis is caused by B. pseudomallei, genetically very similar to B. mallei, but which is an environmental saprophyte capable of infecting humans and a wide range of other animals. Good evidence of animal-to-human, or even human-to-human, transmission of melioidosis is lacking, and so it is most appropriately referred to as a sapronosis, or at most a sapro-zoonosis. Although rare in Western countries, both microorganisms have recently gained much interest because of their potential use as bioterrorism agents and widening geographic footprint. The increasing recognition of melioidosis in humans and recent outbreaks of glanders in animals have led to their description as emerging or reemerging diseases, and melioidosis as a neglected tropical disease. Laboratory-associated infections with both organisms have also occurred, resulting in their categorization as Hazard Group 3 pathogens. In this chapter we review the epidemiology of animal and human cases of glanders and melioidosis, the evidence for different modes of transmission, pathogenesis and clinical features, diagnosis and treatment, as well as public health and disease control issues.