Scanning electron microscopy of Cysticercus fasciolaris (larval Taenia taeniaeformis Batsch, 1786) from the wild rat, Rattus rattus Linnaeus, 1758, morpho-physiology and risk to human health.

Autopsy of Rattus rattus (n=65) revealed 1-7 creamish to white cysts, 2-7 mm in diameter embedded in the liver parenchyma of 12 rats. Dissection yielded 45-65 mm×5 mm sized segmented strobilocercii of Cysticercus fasciolaris (larval Taenia taeniaeformis) coiled inside. Light microscopy indicated large scolices, the rostellum armed with four suckers and one row of taenoid type hooks having long blunt handle with sharp pointed blade, other row of hooks was in the developing stage. The strobila lacked genital organs and ended in a tail-bulb suggesting it was juvenile. SEM showed anterior crown of 19 hooks and poorly developed posterior crown. A collar (66.0-86.0 μm in width) armed with papillae (30.2-35.4 μm base and 12.5-14.5 μm tip) and pores (17.0-22.4 μm in diameter) surrounded the hooks. The body segments were 125-145 μm in diameter, at the tail bud, 380-410 μm in diameter. The segments were armed with pores, 11.5-14.5 μm in diameter. Netted (2.5-4.5 μm wide and of varying lengths) body segments provide flexibility to the worm during attachment. The tail bud was 2.4-2.7 mm in length and 1.5-1.71 mm in width. The SEM data presents a significant advancement over light microscopy and the morphological features generated herein can safely be utilized to correlate with the parasite's physiological functions. This is the first report of R. rattus as a natural intermediate host of T. taeniaeformis, and may pose serious risk to human health in urban areas of Bareilly, India and merits attention.