Encysted metacercariae of Euclinostomum heterostomum (EEMC) is parasitic trematodes infected kidneys of the freshwater fish (Tilapia zillii) in Egypt. The EMC causes severe pathological changes as kidney failure and even death of fish. Development a novel non-chemical approach that decreases the need of anthelmintic drugs, proved to be the only realistic strategy to avoid drug resistance especially with biodegradable eco-friendly plant extracts. In the present study, T. zillii infected with EEMC was 14.5%. Histopathology of the tissue showed marked glomerular congestion with interstitial congestion, hemorrhages, vacuolization and necrosis of tubular epithelium with activation of melanomacrophage center.
The anthelmintic activity of Verbesina alternifolia, Mentha piperita oil extracts on newly excysted metacercariae (EExMC) of Euclinostomum heterostomum was evaluated in vitro. The LC50% & LC100% for V. alternifolia was 400ppm/12hrs and 600ppm/24h, respectively. LC50% of M. piperita was 1000ppm/24hrs. Doses lower did not cause mortality of exposed EExMC. Exposure to both plants caused marked irreversible alteration in tegumental ultrastructure of the exposed EExMC led to mortality. The effect increased with increase in concentration and exposure time. SEM examination of V. alternifolia died EExMC showed ill distinct collar like rings, and lack of transverse ridges which appear highly corrugated edematous tegument. Collar ring in M. piperita exposed group was ill distinct with several blebs around ventral sucker and body
tegument edematous.