Distribution
Oriental, Neotropical, Australian: Warm, temperate climates where there is adequate moisture.
Occurs in temperate forest and grassland, tropical rainforest, tropical deciduous forest, tropical scrub forest.
Economic Importance:
Cost of treatment to kill the parasite; loss of productivity.
Hosts:
Found in small intestine of foxes, dogs, cats; skin of humans.
Usually found in unsanitary, warm, and moist conditions which favor the development of eggs and
infection of hosts.
Feeding
Rhabditiform larval stages feed on bacteria associated with organic matter.
Adult stage feeds on blood and tissue from the intestinal lining of the host.
Parasites draw mucus into their buccal cavity and suck the blood and tissue. The action of
digestive juices and the shearing of teeth form a bolus of tissue that is separated from the host gut and
ingested.
Host blood is drawn almost continuously into the intestine and passed out through the anus.
Blood plasma and corpuscles undergo at least partial digestion in the nematode.
Hookworms
consume up to 1 ml blood per individual per day.
Life Cycle:
Parasites are dioecious, with male and female organs in separate individuals.
Following copulation, female lays her eggs in the hosts intestine. Eggs are passed out in the host feces.
Usual daily output of eggs for a single female hookworm is between 10,000 and 30,000 eggs.
In favorable conditions of moisture, temperature, and oxygen, eggs develop in the soil and hatch when they reach maturity. They release a rhabditiform larva which feeds for a short time and molts twice before becoming an infective filariform larva.
Larva enters the host either by being swallowed or by burrowing into the skin through hair follicles. In the case of pregnant bitches, larvae may enter the
fetus and infect prenatally.
When it reaches the small intestine of the host, the larva molts a fourth and final time and develops to maturity in about five weeks.
Damage:
Infection by a hookworm usually results in bloody diarrhea and anemia.
Hookworm infections undermine the health of the host, causing stunting of growth and general laziness.
Often accompanied by acute mental distress.
Ancylostoma caninum causes a severe rash in humans known as "creeping eruption." Rash is caused because the larvae cannot get below the skin in the abnormal human host.
Management:
References:
Trager, William. 1986. Living Together: The Biology of Animal Parasitism. Rockefeller University, NYC. <BR>
Smyth, J.D. 1962. Introduction to Animal Parasitology. English Universities Press Ltd., London. <BR>
Noble, Elmer R. and Glenn A. Noble. 1982. Parasitology: The Biology of Animal Parasites. Lea & Febiger, Philadelphia. <BR>
Olsen, O. Wilford. 1974. Animal Parasites: Their Life Cycles and Ecology. University Park Press. Baltimore.
Material from Tracy Lindsley, 1995.
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