Research on avian schistosomes

(Older team name: Schistosome Group Prague)

Trichobilharzia regenti

Trichobilharzia regenti is a neuropathogenic avian schistosome which has been discovered and described as a new species by our team in 1998. In addition to birds, the infectious larvae (cercariae) proved to penetrate also the skin of mammals and, therefore, T. regenti (neuro)pathogenicity is intensively investigated.

Adults of nasal bird schistosomes live in the bill mucosa, where also mating and egg laying take place. Histopathologically, petechiae caused by worm migration and egg deposition may occur.

Cercaria of T. regenti penetrates a peripheral nerve isolated from a duck (left). The target tissue of T. szidati migration is the intestinal wall of ducks. Some of the eggs laid by females are trapped in the tissue; formation of granulomas can be noticed macroscopically as well as microscopically in tissue sections.

Confocal laser scanning microscopy can be used for characterization of different organs/tissues of Trichobilharzia. Using specific probes, we focus on organogenesis and stage-specific morphological features of T. regenti. For example, the presence of polymeric or oligomeric F-actin in the eggs, miracidia, cercariae and schistosomula is shown.

Swimmer’s itch, also known as cercarial dermatitis, represents a common non-communicable waterborne cutaneous allergic disease which develops as a consequence of repeated infections by larval stages (cercariae) of schistosomatid flukes. Swimmer’s itch is usually associated with swimming in recreational freshwater lakes, and mostly cercariae of avian schistosomes of the genus Trichobilharzia are reported as a source of infection. Bathing in the sea or brackish waters is rarely mentioned with respect to cercarial dermatitis. Due to a higher number of reports on outbreaks, cercarial dermatitis may be regarded as an emerging disease.

CURRENT MAIN RESEARCH STREAMS in the study of avian schistosomes (laboratory models: Trichobilharzia regenti, Trichobilharzia szidati):

Immune responses of snails and vertebrates

• Snail hemocyte reactions against compatible and incompatible schistosome larvae

• Immune response in vertebrate skin; immune processes participating in cercarial dermatitis

• Inflammatory reactions in target tissues, histopathology of parasite migration within bird and mammalian bodies

• Screening for candidate antigens and introduction of specific immunodiagnosis

Biologically important parasite proteins

• Schistosome peptidases (mainly cathepsins) involved in skin penetration, tissue migration and digestion

• Hyaluronidases and lectins of bird schistosomes and their role in host-parasite interaction

Systematics/life cycles

• Morphology (incl. ultrastructure) and behavior of schistosome developmental stages

• Identification of natural/experimental intermediate and final hosts