1. Ancylostoma Duodenale and Necator Americanus
By Marquetta Valdez

2. Some Facts….
Hookworms infect an estimated 1 billion people worldwide, mostly in tropical and sub-tropical climates
A. duodenale and N. americanus are the two hookworms that infect humans
A. duodenale is found in southern Europe, northern Africa, India, China, the Middle East, and the Americas
N. americanus can be found in the southeastern U.S. and Australia

3. Life Cycle and Reproduction
Eggs are passed in the feces and hatch into rhabditiform larvae in about 48 hours in the feces or in the soil
A. duodenale
N. americanus
Eggs are generally µm by µm and are oval shaped with a thin shell

4. Rhabditiform Larvae (wet mount)

5. Life cycle continued
Juveniles feed on feces for about 3 days then molt into 2nd stage juveniles
They molt again 5-10 days later into filariform larvae. Can survive 3-4 weeks outside host.

6. Life Cycle
Infect humans by penetrating skin and then travel to the heart and lungs where they penetrate the pharynx and are swallowed. When they reach the small intestine they attach to the intestinal wall and feed on blood.
Cutting plates in N. americanus
Cutting teeth in A. duodenale

7. Life Cycle Worms molt again two more times to reach maturity
A. duodenale adult males measure 8-11mm with females being 10-13mm
N. americanus adult males measure 7-9mm and females measure 9-11mm
Adult worms copulate and eggs appear in the feces in about 6 weeks (females can produce sever thousand eggs in one day)
Cycle starts over again and adults live 1-2 years

8. Life Cycle

9. Transmission
Filariform juveniles wait in soil or feces and wave back and forth to increase chances of finding a host
Filariforms then penetrate the skin (usually hands or feet)
Children, elderly people and people who work about contaminated soil are at high risk

10. Pathogenic Effects
Asymptomatic until worms have already started multiplying
Symptoms include:
Irritation of skin at site of penetration
Iron-deficiency anemia
Abdominal pain
Diarrhea
Loss of appetite
Weight loss
Tiredness
Difficulty breathing
Cardiomegaly
Irregular heartbeat
Extreme cases include stunted growth and mental retardation

11. Diagnosis Stool samples showing eggs or actual worms
Watching for symptoms

12. Control and Treatment Scientist are trying to develop a vaccine
In some countries, infections aren’t treated because they are so common
Drugs of choice are Albendazole, Mebendazole, and Pyrantel Pamoate

13. Prevention
Wear shoes
Monitor the disposal of humans feces

14. Works Cited
"Hookworm Image Library." Division of Parasitic Diseases. Center for Disease Control. 29 Sept <
"Hookworm Infection Fact Sheet." Parasitic Disease Infection. Center for Disease Control. 3 Oct <
"Hookworm." Parasites and Health. Center for Disease Control. 29 Sept <