Worm eggs are passed out in feces and break when in fresh water. Larvae find snail host in which to replicate, then move into freshwater crab or crayfish. Humans eat uncooked seafood. Worms migrate in pairs from stomach through intestinal wall and diaphragm to lungs, where they mate. Eggs hatch on contact with water, releasing the parasite miracidium.
Parasite moves into a freshwater snail, where it replicates.
It is released back into water, then penetrates human skin within seconds and moves into blood vessels. Within 30 to 45 days, miracidium grows into worm, which can lay 200 to 2,000 eggs per day for an average of 5 years. The virus incubates for 8 to 12 days and replicates. The next time the mosquito takes a blood meal, the virus is injected into a human's blood. Worm larvae are ingested by a mosquito and develop.