The Use of Imaging to Detect Schistosomes and Diagnose Schistosomiasis

Several imaging modalities have been employed to examine schistosomes and monitor schistosome-induced pathology. Ultrasound is a noninvasive imaging method that has long been used in the laboratory and in the field to evaluate pathological changes, notably fibrosis, that arise as a consequence of the host response to schistosome eggs lodging in a variety of tissues. Ultrasonography has been widely used to monitor changes in the extent of fibrosis and in spleen/liver enlargement following chemotherapeutic treatment for schistosomiasis. Imaging methods to monitor schistosomes themselves in vivo (as opposed to detecting schistosome-induced pathology) include positron emission tomography and fluorescence molecular tomography. Both approaches rely on schistosome uptake of tracers that are introduced into infected animals and that can be detected externally. These methods have been used to successfully detect schistosomes in vivo and to monitor their elimination following chemotherapeutic treatment. Direct monitoring of live schistosomes in vivo has been achieved using intravital microscopy, when the infected tissues of anaesthetized animals are exposed. Finally, schistosome eggs have been visualized by confocal laser scanning microscopy in infected mice as well as in a human patient with schistosomiasis hematobium. Further advances in imaging technologies seem likely to provide greater insight into disease progression and into the biology of schistosomes in the most relevant setting-within a live animal.