Schistosomiasis Cycle

Follow the steps below and following an illustration of the schistosomiasis cycle.

  1. Adult worms live inside the veins inside the liver. During mating, they travel to the veins of the intestinal wall, thus running the opposite way to blood flow.
  2. Once there, they separate and the female starts laying eggs (more than 1,000 a day) in small veins that are close to the wall of the large intestine. The eggs are lined up and each has a small lateral thorn. Each produces enzymes that pierce the intestinal wall and one by one are released into the light of the intestine.
  3. Mixed with the feces, they reach the external environment. Falling into the appropriate medium, such as ponds, dams and standing water dams, each egg breaks and releases a ciliated larva, the miracidium, which remains alive for only a few hours.
  4. To continue its life cycle, each miracide must penetrate a Biomphalaria snail. Inside the snail, it loses its eyelashes and goes through a cycle of asexual reproduction that generates, after 30 days, numerous forked-tailed larvae, cercariae.
  5. Each cercaria remains alive for 1 to 3 days. During this time, it needs to penetrate through one's skin through active movements and using digestive enzymes that make their way between the cells of the human skin. At the point of entry, itching is common. Reaching the blood, they are directed to their place of life.