Which statement describes the travel and effect sequence of schistosome worms after skin entry?

• A. Worms penetrate the skin, enter circulation, migrate to liver/bladder/intestine, and damage tissue
• B. Worms enter via the bloodstream and immediately cause brain damage
• C. Worms are excreted in stool and cause dehydration
• D. Worms remain in the skin and cause no systemic effects

Answer: (A)

Cercariae that enter through the skin quickly move into the blood, travel to the liver where they mature, and then migrate to their final venous sites in either the intestines or the bladder, where they lay eggs that drive tissue damage. This path—skin entry, circulation, liver maturation, and subsequent residence in mesenteric or vesical veins with egg-induced inflammation—explains why tissue injury occurs in the liver, intestines, or bladder.

Brain involvement is not the typical early or primary path after skin entry, so sudden brain damage isn’t the expected travel sequence. Eggs may be excreted in stool or urine depending on species, but that is part of the parasite’s lifecycle and transmission, not the immediate travel route described. Finally, staying entirely in the skin with no systemic effects is unrealistic, since the parasites circulate and cause downstream pathology.