Epitheliocystis is a severe disease affecting the gills and skin of fish that can lead to high rates of mortality. Infection has been documented in over 90 species of both freshwater and marine fish. Epitheliocystis is characterized by development of cysts in the gill epithelia and may lead to the fusion of gill lamellae . The etiology, transmission, and epidemiology of epitheliocystis remains largely unknown. It is believed that the causative agent of this disease comes from a family of pathogenic, intracellular bacteria, that form vacuoles that closely resemble those of the human pathogens from the Chlamydiaceae family. We hypothesize that Chlamydia-like organisms (CLO), or environmental chlamydiae, are an important etiologic agent of epitheliocystis.
We developed a zebrafish model to determine susceptibility to infection, mode of transmission and factors that influence the disease. Two Chlamydia-like organisms, Waddlia chondrophila and Simkania negevensis, were used to model the pathogenic intracellular bacteria, while zebrafish (Danio rerio), exposed/infected using different models