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USAID

USAID's NTD Program
USAID's NTD Program

Hookworm

Life Cycle of Hookworm

Step 1: Eggs are passed in the stool. Hookworm eggs are not infective.

Step 2: Under favorable conditions (moisture, warmth, and shade), larvae hatch in one to two days.

Figure explaining the lifecycle of hookworm.Step 3: The released rhabditiform larvae grow in the feces and/or the soil, and after 5 to 10 days (and two molts), they become filariform (third stage) larvae, which are infective. These infective larvae can survive three to four weeks in favorable environmental conditions.

Step 4: Upon contact with the human host, mostly through the skin (can also be ingested), the larvae penetrate the skin and are carried through the veins to the heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed.

Step 5: The larvae reach the small intestine, where they reside and mature into adults. Adult worms live in the lumen of the small intestine, where they attach to the intestinal wall, with resultant blood loss by the host. The presence of between 40 and 160 adult hookworms in the human intestine results in blood loss sufficient to cause anemia and malnutrition. Most adult worms are eliminated in one to two years, but longevity records can reach several years.

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