With the laudable aim of showing 'how the genome has informed and changed our understanding of the biology of Leishmania' and 'the implications in terms of discovering novel diagnostics, chemotherapeutic agents and vaccines', 48 authors in 13 chapters unzip the molecular biology of the pathogen that causes the complex parasitic disease leishmaniasis. The Leishmania parasite is a flagellated protozoan, existing as an extracellular promastigote in the female sandfly vector and as an intracellular amastigote in the mammalian host, where it survives and multiplies in the inhospitable location of the phagolysomal compartment of the macrophage, and subsequently subverts the host immune response to cause leishmaniasis. The understanding of the mechanisms that enable this process, the variation between the 17 different species of Leishmania that infect humans, and their different tissue tropisms and virulence patterns pose a major challenge. The genome (and ancillary '-omes') are helping us to resolve some of these questions. The recent publication by Peacock et al. (2007) has demonstrated how some of the challenges around species differences can be unravelled. More will come when studies are more focused on the disease relevant amastigote and we are clearer about the predictive value of mouse models for human disease.

The volume is up-to-date; the genome was published in 2005 and the most recent references in the book were published in 2007. There is a richness of information - chapters on gene regulation and the metabolome are particularly engaging. It is therefore a shame that some errors, for example over chemotherapy (details and facts), in other chapters create concern. A further problem lies in the aims of the volume itself and the concept of 'implications'. The premature expectation of great revelations from the genome is a minor concern compared with the expectation that the genome is the basis of discovery of new tools for disease control - it is only a small (and early part) of the process. As pointed out in the vaccine chapter, the 'roadblock is to identify a mode of delivery'. With a disease where the real burden of infection in humans in unknown, where the introduction of new drugs is threatened by misuse, where the differing sensitivities of diagnostics between countries cannot be explained, complex problems must be considered at all levels from the genome to access. Let us enjoy a volume that provides a valuable overview of the molecular biology and biochemistry of these fascinating parasites, their metabolic pathways, differentiation process, and their surface molecules without burdening important scientific advances with unreal expectations.